Selected TechnologiesAffecting Land andWater Management

PageThe Water Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299The Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

Water Management.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Water Management by Conjunctive Use.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309Land Use Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313Computers and Information Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

Chapter XI References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

List of Tables

Table No. Page76. Comparison of Irrigation, Overland Flow, and

Infiltration-Percolation of Municipal Wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . 30677. Expected Quality of Treated Water From Land Treatment . . . . . . . . . . . . . . . . . . 30878. Summary: Issues Surrounding Water Reuse for Irrigation . . . . . . . . . . . . . . . . . . 30979. Crop Yields at Various Levels of Application of Wastewater,

Pennsylvania State University . .............................0.. . . . . . . . . . 30980. Conjunctive Use of Surface Water and Ground Water Resources . . . . . . . . . . . . 31181. Examples of Human Substitutions for Biological Processes . . . . . . . . . . . . . . . . . 32382. Gross Revenue to Western Statesa From Hunting and Fishing Licenses in 1981 32583. Relationships Between Agriculture Practices and Fish and Wildlife,Sacramento Basin and Delta-Central Sierra Hydrologic Study Areas . . . . . . . . . . . . 326

List of Figures

Figure No, Page69. Crop-Management Model for Flexible Cropping . . . . . . . . . . . . . . . . . . . . . . . . . . . 30170. Sample Crop-Management Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30271. The Wastewater Renovation Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30572. The Major Types of Wastewater Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30773. Summary Information for Using Big Sagebrush in Rangeland Reclamation . . . 316

Chapter XI

Selected Technologies AffectingWater and Land Management

Continued agricultural productivity of aridand semiarid lands will require more carefuland integrated management of many re-sources, including water. Improved water andland management can help to restore the in-herent productivity of many agricultural landsthat suffer from erosion, soil compaction, soilsalinity, or other adverse conditions. In irri-gated areas, better water management maycompensate for the decreasing availability of

use of technology and “smart” users when re-sources become less available. This chapterhighlights an assortment of these lesser known,and sometimes unconventional, practices formanaging water and land. This discussion isnot all-inclusive, however. Rather, each tech-nology has shown its usefulness i n some loca-tions and may play an increasing role in aridand semiarid agriculture in the Western UnitedStates.

affordable water which many experts predict,

Managementpower and there

technologies rely on brain-is no substitute for intelligent

SETTIN6

Most irrigation systems and arid/semiarid-land cropping systems developed to managewater; historically, patterns of agricultural landuse and agricultural practices reflected thischaracteristic. Today, the more promising con-temporary management schemes show a sim-ilar understanding of water in arid/semiaridlands: the limited absolute amounts of water,its spatial and temporal unevenness, its suscep-tibility to effectite exhaustion, and the inter-connected nature of different water resources.As an example, some areas are using the water-shed (the fundamental hydrologic unit) as apolitical management unit. In other locations,individuals recognize that it is difficult to af-fect one hydrologic: component without alter-

ing others and have linked the use of groundand surface waters.

The use and management of water, then, isbecoming more attuned to economic and nat-ural resource conditions. For some regions,however, the most precise use of water requiresmore careful land management rather than wa-ter management per se. Rangeland agriculture,for example, involves managing plants and an-imals to provide optimal production from ex-isting precipitation. Although the amount ofwater involved is small compared to irrigatedagriculture, the land areas are vast and agri-cultural production from these regions is sig-nificant nationally.

299

— . —

300 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands

Water

THE

Management

Flexible Cropping

INTRODUCTION

—

In much of the semiarid region, low precip-itation limits dryland crop production to sometype of crop-fallow (noncropping season) sys-tem. Traditionally, farmers in the low rainfallareas of the northern and central Great Plainshave strictly practiced this alternate-year rota-tion. In the slightly higher rainfall regions ofthe southern Great Plains, more intense rota-tions such as two crops every 3 years or an-nual cropping have been possible.

TECHNOL0GIES

Dryland farmers in recent years have prac-ticed methods of crop production that improvewater storage during the fallow period, suchas stubble mulch tillage and conservation til-lage (ch. VIII). These technologies have helpedincrease the amount of water stored during thefallow period. Although there have been trade-offs, for example, in weed control, this higherlevel of soil water is sufficient in some casesto allow farmers to grow crops each year,

Flexible cropping is an outgrowth of this de-velopment. In this system, a crop is plantedwhen stored soil water and predicted rainfallare favorable for a satisfactory yield. When

Box X.—”Best Management Practices”

The importance of management practices for achieving various resource objectives has beenlong recognized. Conservation plans initiated by the Soil Conservation Service during the 1930’s,for example, recommended certain management practices for controlling soil erosion. “Best manage-ment practices” for controlling nonpoint sources of water pollution were formally recognized inthe Federal Water Pollution Control Act (FWPCA) of 1972 (Public Law 92-500) as amended by theClean Water Act of 1977. States were instructed to develop and implement “best management prac-tices” to reduce this type of pollution. The actual “best” practices were not specified in the legisla-tion nor in subsequent regulations issued by EPA.

USDA has remained involved with the original conservation plans as well as more recent pro-grams. The Clean Water Act authorized USDA to provide technical and financial assistance tofarmers and ranchers for adoption of FWPCA’s best management practices. While the programhas moved slowly, it has spurred recognition that combinations of practices applied at the water-shed level are most likely to meet multiple objectives: water conservation, erosion control, cleanair, sustained food and fiber production, wildlife habitat, and recreational lands.

Computerized agricultural models make the evaluation of management packages simple andeffective. For example, the long-term effects of weather and the implementation of new tillage prac-tices can be tested locally and regionally before investments are made. A variety of agriculturalmodels are available for these and related purposes. These include: EPIC (Erosion ProductivityImpact Calculation), CREAMS (Chemicals, Runoff, and Erosion from Agricultural ManagementSystems), and SWAM (Small Watershed Model).

While technology exists for evaluating management practices, it has not been used to prepareintegrated-management packages for farmers. Some people believe that an adoption bottleneckhas resulted. Debate continues regarding who (i.e., public or private, Federal or non-Federal groups)should be responsible for putting together management packages. It is unlikely, however, thatUSDA’s Agricultural Research Service (ARS) will assume major responsibility. The portion of theARS budget allocated to integration of agricultural systems is expected to increase from 2 percentin 1982 to only 3 percent in 1990.

SOURCE: U.S. Depafiment of Agriculture, Agricultural Research Service, “Agricultural Research Program Plan, &Year Implementation Plan, 19w19QIY’ (Washington,D. C.: U.S. Government Printing Office, 1983).

-—

Ch. XI—Selected Technologies Affecting Water and Land Management ● 301—

crop prospects are not favorable, no crop isplanted, and a field is left fallow to store addi-tional soil water.

ASSESSMENT

Flexible cropping systems were developed inthe last few years for use in the northern GreatPlains, Such systems have wide potential ap-plication throughout the Great Plains, butdetailed procedures have yet to be developedfor their use.

Success of a flexible cropping system re-quires a combination of preplanning, in-season,and postharvest practices. Before planting, afarmer assesses root-zone water-supply re-quired for planting time and determines pre-dicted seasonal precipitation for the growingseason. Soil characteristics, crop-water require-ments, and depth of rooting for different cropsare also considered. If a farmer decides thatsoil moisture and predicted precipitation aresufficient, tillage operations are timed to max-imize the water available to the crop, Fertilizeris applied to stimulate root growth during thegrowing season, Weed control and snow man-agement are used after harvest to collect pre-cipitation for the next growing season.

It is difficult for an individual farmer to eval-uate all of these factors, and thus computerizedmanagement guides and users’ manuals havebeen developed. In Montana, for example,these materials help farmers decide the bestcropping and soil management options forwheat, barley, oats, and safflower based onstored soil water and expected growing seasonprecipitation (figs. 69 and 70),

Besides making more systematic and optimaluse of stored soil-water supplies and growingseason precipitation, research indicates thatthe flexible cropping system may prevent theformation of saline seeps (ch. VIII), since soilwater is used before it moves below the rootzone.

Many of the limitations associated with flex-ible cropping systems are similar to those ex-perienced with other water-conservation tech-nologies, For example, if plant-barrier systemsare used to trap winter snow. weeds mav in-

Figure 69.—Crop-Management Model for FlexibleCropping

This model, developed in Montana, depicts grain yield as afunct ion of water supply crop v a r i e t y w e e d s fert i l i ty plant

Ing date and rotation. Management decisions and crop infor-

mation are then provided to the user, who types responses toquestions asked by the compute r

Wate rmodule

Crop selection and rotationI

crease. If conservation tillage is employed,managers may have difficulty seeding cropsinto the resultant residue. Where snow is col-lected, water might not filter properly intofrozen soil.

Flexible cropping systems also have a uniqueset of management limitations. Crop rotations

L are a highly effective way to avoid weed, in-

302 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— —

Figure 70.—Sample Crop-Management Worksheet

SOURCE P O Kresge and A D Halvorson, Fexcrop User 's ManualComputer Assisted Dryland Crop Management Montana StateUniversity Cooperative Extension Service Bulletin 1214. Bozeman.Mont 1979

sect, and disease buildup, but they have be-come rare in many regions because of past eco-nomic constraints, Therefore, little informationexists to guide farmers in choosing possiblecrop rotations. In addition, some crops* aredifficult to work into a flexible cropping systembecause they are planted in the fall before mostwater is accumulated and total water suppliesare known.

Also, social and economic considerationscurrently limit employment of flexible crop-ping systems. Farmers generally view flexiblecropping as a riskier approach than traditionalcrop-fallow practices, one that requires ahigher management commitment. Some farms

may have the labor and time to conduct the in-tensive soil-water monitoring needed for its ap-plication, but total reliance on a flexible crop-ping system often requires resources (e.g., la-bor, capitol, and access to agricultural con-sultants who can assist in monitoring and plan-ning operations) available most readily to largeoperations. Federal policies governing crop di-versions and set-asides may pose a further bar-rier to adoption. For example, policies requir-ing farmers to reduce acreage in order to beeligible for certain benefits (e. g., commodityloans and disaster payments) may be in effectin years when soil-water conditions wouldallow full production. In other cases, set-asidesmay increase flexibility by allowing installationof soil- and water-conserving practices withoutlosing a crop.

Irrigation ScheduIing

INTRODUCTIONTraditionally, many growers schedule irriga-

tion periods by examining crop appearanceand soil-water conditions and judging futureweather. Others time water applications by thecalendar. Still others are forced to schedule ir-rigations by water delivery rotation systems.These scheduling procedures give generallysatisfactory results but may not make the mostefficient use of water, maximize crop yields,or save energy.

The concept of scientific irrigation schedul-ing” has received much attention in recentyears. It takes into consideration:

c precipitation and evapotranspiration sincethe previous irrigation,

c allowable soil-water depletion at the partic-ular growth stage of the crop, and

● expected precipitation and crop-water re-quirements before the next irrigation.

To assess the need for water application, twotechnically sophisticated methods are used:1) environmental and plant monitoring, and2) a water budget technique. In the first meth-od, tensiometers, electrical resistance gypsum

* For example, winter wheat.*The prediction of the time and amount of water required for

the next and future irrigations.

Ch. XI—Selected Technologies Affecting

blocks, or neutron probes are used to measuresoil water (ch. VIII), Plant water stress is in-ferred through use of infrared thermometersor pressure chambers, Some of these types ofmonitors do not indicate how much irrigationis needed.

In the water budget method, an alternativeto environmental monitoring, the crop rootzone is visualized as a reservoir of availablewater. Water is withdrawn from the root zonethrough evaporation or drainage and addedthrough rainfall and irrigation. If the volumeof water in the root zone—the amount of waterthat can be drained without stressing the plant(or the allowable depletion)–and the depletionrate (or evapotranspiration) are known, thedate of the next irrigation can be predicted.Coupled with accurate weather forecasts, thismethod allows for accurate irrigation sched-uling.

ASSESSMENT

Irrigation scheduling services (ISS) are pro-vided to about 1 million acres in the WesternUnited States by Federal and State agenciesand private consultants (1 3). Most services arebased on computer predictions of time andamount of irrigation.

Several advantages of irrigation schedulingservices have been noted by researchers. Lim-ited information indicates that crop yields withirrigation scheduling can be increased by anaverage of 10 to 30 percent primarily a resultof proper timing and sufficient water applica-tion although other research has been unableto document significant increases. Schedulingmay reduce the number of irrigations per sea-son by making maximum use of soil water andrainfall, It may also help to reduce pollutionof ground water because less excess water ispercolated through the soil. In areas whereelectricity is used for pumping irrigation water,irrigation scheduling may also help managepeak electrical loads. Moreover, because plantenvironmental conditions are better known,this technology permits managers to plan waterrotations among fields, pesticide applications,tillage operations, and other activities to min-imize crop stress and yield reductions.

Water and Land Management 303

A number of technical and social factors af-fect the adoption of irrigation scheduling. First,the effectiveness of the system depends on thetotal water application and measurement sys-tem, including delivery, application, and irriga-tion. Before scheduling can be implemented,each of these systems should be evaluated todetermine capacity, needs, flexibility, and lim-itations. Surface water delivery systems to thefarm in some areas are fixed and may not beadapted to scheduling techniques based oncrop-water needs because of the short noticeinvolved (ch. VII).

Second, field verification of computer predic-tions about environmental conditions is nec-essary because of site-specific variability in thedepth of water applied at each irrigation, thecrop rooting depth, soil water storage capaci-ty, allowable depletions, effective rainfall, andcrop evapotranspiration. These field checks re-quire competent and trained personnel whocan communicate effectively with growers. Forexample, the Bureau of Reclamation has devel-oped an irrigation management service pro-gram to help irrigators schedule water deliv-eries and application. Private agricultural con-sultants have also developed scheduling serv-ices, These dual efforts raise questions aboutthe government and private role in onfarm wa-ter management (19).

Third, irrigation scheduling services areadopted when definite economic benefits canbe readily identified by the grower, since theseservices are costly and beyond the means ofmany farmers. Inexpensive and readily avail-able water supplies reduce the incentive to im-plement scheduling. As discussed in chapterV, water law may often inhibit farmers fromconserving irrigation water onsite since thewater “saved” does not become available forother uses on the same farm. Again, the short-term economic incentive for adopting the tech-nology may not be adequate, now, but this sit-uation may change rapidly if water costs reflectmore closely replacement value of water,

Fourth, there is general skepticism that yieldscan be improved by altering irrigation prac-tices. Scheduling services can increase net in-come to growers to the extent that the level of

304 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— - — —

Box Y.—Water Management in Israel

Israel has limited freshwater supplies but a rapidly growing population. Consequently, water-management strategies during the 1980’s have shifted from development of new supplies to manage-ment of water demand. Nationalized water resources, a national supply system, and elaborate pro-grams of technical assistance to water users are important components of this approach. Thesearrangements were possible in part because Israel is a small country and neither farm groups norwater-rights holders existed to oppose their initiation.

Several methods are used to manage water demand: metering, pricing, and allocation. All waterusers are metered and receive annual licenses for ground water, runoff, and sewage effluents. Waterprices are adjusted nationally, and larger water users pay higher prices. Water costs are high, re-flecting the true scarcity of the resource. Each farm is allocated its water annually, an allocationwhich may be decreased the following year.

As a result of these policies, Israelis a leader in several water-use technologies. These includewastewater reuse, use of brackish water, and specialized irrigation systems. A close-working rela-tionship between researchers and farmers has also ensured that research results are quickly adoptedand often cooperative groups of farmers manufacture new instruments themselves.

SOURCE: U.S. Congress, Office of Technology Assessment, “Water and Agriculture in Arid Lands: selected Foreign Experience-A Background Paper” (Washington,D.C.: U.S. Government Printing Office, OTA-BP-F-2O, May 1983).

some production input is decreased, the qualityof the crop is increased, or yields are increased.Among those who provide scheduling services,there may be an overemphasis on the degreeto which yields can be improved or irrigationcan be reduced.

In sum, irrigation scheduling is a necessarybut incomplete management tool for increas-ing irrigation efficiencies. It can help to con-serve water when precise control is availablethroughout the water distribution system.

Wastewater Reuse

INTRODUCTION

Wastewater reuse, defined as the use of landto renovate sewage effluent from municipal orindustrial sources, is receiving increased atten-tion as a possible way to augment irrigation wa-ter supplies and to reduce the water pollutionthat might otherwise occur if such wastewaterwere released directly to waterways. Thosewho advocate wastewater reuse consider thatwastewater and the nutrients it contains areresources rather than refuse. Wastewater pro-vides water and nutrients to plants, In return,biological and chemical processes that occurin the soil, micro-organisms, and plants are

thought to cleanse the wastewater, Accordingto supporters of this practice, renovated, safewater may then percolate downward to re-charge the ground water reservoir or be dis-charged directly to surface water (fig. 71).

The idea of using land to treat wastewateris not new. Parker (22) notes that “treatmentand disposal of sewage by land extensiveschemes of irrigation is the oldest form of themodern methods of purification, ” These meth-ods dominated U.S. municipal sewage-treat-ment systems until the early 20th century, butgradually diminished in importance as metro-politan areas expanded, large expanses of landadjacent to urban areas became limited, andconcerns grew about possible public health andwater-quality effects. Sewage treatments thatused less land were developed as well.

Since the early 1970’s, interest in land appli-cation technologies has revived, In part, thisinterest reflects a greater public awareness ofthe costs of treatment to meet health standardsand of potential pollution and degradationcaused by the discharge of partially treatedwastes into waterways. It also reflects concernsabout the growing scarcity of unallocated sur-face water supplies and rates of ground waterdepletion, especially in the West. Finally, Fed-

—

Ch. Xl—Selected Technologies Affecting Water and Land Management ● 305— —— —-—

SOURCE William E Sopper “Surface Application of Sewage Effluent, ” Planning the Uses and Management of Land, Marvin T Beatty, et al (eds ) (Madison, Wis.: AmericanSociety of Agronomy, 1979), pp 633-663 (No 21 in the series Agronomy)

eral actions—e.g., passage of the Water Pollu-tion Control Act of 1972 (Public Law 92-500)–have stimulated interest in reuse technologiesto balance treatment costs.

Wastewater Treatment Methods

Wastewater contains two major categories ofcontaminants: biological and chemical. Biolog-ical contaminants include bacterial or viralpathogens and intestinal parasites. Chemicalcontaminants include substances such as ni-

trates, sodium, heavy metals (e. g., cadmium,lead, and zinc), oil, grease, and pesticides,

Levels of treatment generally recognized forwastewater are primary, secondary, and ter-tiary. This classification is based on the remov-al of suspended solids and on the reduction ofbiochemical oxygen demand (BOI))-i.e., theoxygen needed to meet metabolic needs of aer-obic micro-organisms in water containing or-ganic matter. Primary treatment consists ofmechanical and physical removal of suspended

306. Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands

solids. This process is estimated to remove ap-proximately 35 percent of the BOD and 60 per-cent of the suspended solids in raw sewage wa-ter (26).

Secondary treatment introduces biologicalprocesses—e.g., activated sludge or tricklingfilters—to remove much of the remaining sus-pended solids and organic matter. Secondarytreatment will remove from 80 to 95 percentof the BOD and suspended solids (26).

Tertiary, or advanced wastewater, treatmentis used after primary and secondary treatmentsto reduce BOD further, remove suspended sol-ids, lower nutrient concentrations, and im-prove the effectiveness and reliability of dis-infection. Land application of wastewater isconsidered one method of tertiary treatmentalong with others such as chemical coagula-tion, clarification, filtration, activated carbontreatment, and reverse osmosis.

Advanced wastewater treatment by land ap-plication can be achieved in a variety of ways,depending on the goal of the treatment, thecomposition of wastewater, and characteristicsof the waste site. The three most commonlyused methods for land application are slow-rateirrigation, overland flow, and rapid infiltration-

percolation, Table 76 compares the three meth-ods by use objectives.

Slow-rate irrigation (fig, 72-A) is probably themethod used most often and with most poten-tial for agricultural use. In this process, waste-water is applied to the soil surface by a fixedor moving sprinkler system or by surface irri-gation. Water application rates are generallylow and are largely determined by climate, soil,and the water and nutrient needs of the crops.Treatment proceeds as vegetation and soilmicro-organisms act to remove and alter waste-water as it percolates through the soil.

Overland flow reuse systems (fig. 72-B) alsorely on a vegetative cover to effect waste treat-ment but differ from slow-rate methodsbecause crop production is usually not a ma-jor objective, In this process, wastewater is ap-plied over the upper parts of vegetated terracesand allowed to flow in a thin sheet down therelatively impermeable surface to runoff col-lection ditches, Only small amounts of waste-water infiltrate into the soil or percolate to theground water. Renovated water that is col-lected may be reused or discharged directly tosurface water. Treatment occurs by physical,chemical, and biological means.

Table 76.—Comparison of Irrigation, Overland Flow, andInfiltration-Percolation of Municipal Wastewater

Type of approach

Overland lnfiltration-Objective Irrigation flow percolation

Use as a treatment process with a recovery of ‘-

renovated water a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-70 ”/0 50-800/o Up to 970/0recovery recovery recovery

Use for treatment beyond secondary:1. For BODb and suspended solids removal . . . . . . . . . . . 98 + 0/0 92 + % 85-990/o2. For N removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 + %c 70-900/0 0-50 ”/03. For P removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80-99°/0 40-800/o 60-950/o

Use to grow crops for sale. . . . . . . . . . . . . . . . . . . . . . . . . . . . Excellent Fair PoorUse as direct recycle to the land . . . . . . . . . . . . . . . . . . . . . Complete Partial CompleteUse to recharge ground water . . . . . . . . . . . . . . . . . . . . . . . . . 0-70 ”/0 0-10 ”/0 up to 97 ”/0Use in cold climates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Faird d ExcellentaPercentage of applied water recovered depends on recovery technique and the climatebBOD = Biochemical oxygen demandCDependent on crop uptakedConflicting data—woods Irrigation acceptable, cropland irrigation marginal‘Insufficient data

SOURCE William E Sopper, “Surface Application of Sewage Effluent,” Planning the Uses and Management of Land, MarvinT Beatty, et al (eds ) (Madison, Wis American Society of Agronomy, 1977), pp 633663 (No 21 in the series Agronomy)(Original source U S Environmental Protection Agency, “Process Design Manual for Land Treatment of MunicipalWastewater, ” EPA 62511-77-008 (Washington, D C , 1977).

.

Ch. XI—Selected Technologies Affecting Water and Land Management . 307— . . . .

Figure 72.—The Major Types ofWastewater Treatment

A. Slow-rate irrigation

Wastewater IS applied to the soil surface and allowed topercolate downward Treatment proceeds as soil, vegetation,and soil micro-organisms remove nutrients and suspendedsolid material.

B. Overland flow reuse

Wastewater IS applied to a sloping surface and allowed tof low over the soi l surface to runoff col lect ion d i t ches T rea t -ment IS a result of physical, chemical, and biologicalprocesses

C. Rapid-infiltration percolation

Wastewater IS applied by flooding or sprinkling to highlypermeable soils in basins. As the wastewater percolates Into

the soil renovation occurs

Evaporation

SOURCE William E Sopper “Surface Application of Sewage Effluent,” Planningthe Uses and Management of Land, Marvin T Beatty, et al. (eds.)(Madison, Wis. American Society of Agronomy, 1979), pp. 633-663. (No.21 in the series Agronomy )

Rapid infiltration-percolation, the third meth-od, uses less land area to effect treatment thando the other two methods. The main objectivein this system is ground water recharge (fig.72-C). Wastewater is applied to highly perme-able soils in basins by flooding or sprinkling.

The basins may or may not be vegetated. Ren-ovation occurs through natural processes in thesoil as water percolates downward.

The degree of success for wastewater treat-ment varies with the type of method used toapply wastes, Table 77 shows expected treat-ment performance for these three processes.

ASSESSMENT

Municipal wastewater is now used for irriga-tion, However, information on the number ofcommunities that use land treatment for sew-age renovation and the number of individualswho use wastewater to irrigate agriculturalcrops is inexact, because funding for these sys-tems may be through the Federal Government,industry, or private sources, With Federal fund-ing, estimates are that approximately 1,000municipalities use land application to treatwastes (31). Unpublished data from the U.S.Geological Survey (USGS) indicate that in 1980,0,5 billion gal/day of effluent were used for ir-rigation compared to 290 billion gal/day offresh surface water and 88 billion gal/day offresh ground water.

Some communities use municipal wastewa-ter for irrigation for parks, golf courses, andgreenbelts and Federal and State guidelineshave been developed for its application (e.g.,22,36). In California, for example, irrigation re-turn flows of relatively good quality are appliedto wetland areas to maintain natural vegeta-tion. These areas are then used for cattle graz-ing in summer and hunting in the fall. Chemi-cal wastes from potato processing plants havealso been used for irrigation. In spite of thesesigns of acceptance, widespread adoption ofreuse systems for most agricultural crops ishindered by numerous biological, social, eco-nomic, and legal questions and a lack of long-term research on the subject. Chapter IV dis-cusses some of the more serious public healthquestions that still need answers before full-scale programs should be adopted. Table 78presents a summary of issue areas that requireresolution.

Three examples illustrate the complexity ofthese issues. First, regarding the question of

308 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands

Table 77.—Expected Quality of Treated Water From Land Treatment (mg/liter)

Slow rate’ Rapid infiltration Overland flowc

Constituent ‘Average Maximum ‘Average Maximum Average Maximum

BOD ... . . . . . . . . . . . . . . . . . . . <2 < 5 2 < 5 10 <15Suspended solids. ., . . <1 < 5 2 < 5 10 <20Ammonia nitrogen as N . . <0.5 < 2 0.5 < 2 0.8 < 2Total nitrogen as N . . . . 3 < 8 10 <20 3 < 5Total phosphorus as P . . . . . <0.1 <0.3 1 < 5 4 < 6—.aPercolation of primary or secondary effluent through 1.5 m (5 ft) of soiI.bPercolation of primary or secondary effluent through 45 m (15 ft) of soilCRunoff of municipal wastewater over about 45 m (150 ft) of slope

SOURCE William E Sopper Surface Application of Sewage Effluent, ” Planning the Uses and Management, of Land, MarvinT Beatty et al (eds ) (Madison, Wis. American Society of Agronomy, 1977), pp 633-663 (No 21 in the series ofAgronomy) (Original source U S Environmental Protect Ion Agency “Process Design Manual for Land Treatmentof Muntcipal Wastewater, EPA 62511-77008 (Washington, D C 1977 )

land productivity with reclaimed water, dataindicate that the yields of crops irrigated withwastewater usually increase or remain thesame (9,26), but crops seem to vary in their tol-erance to wastewater application (table 79). Forexample, research in Hawaii on sugarcanetested the dilution of wastewater required foroptimal sugar yield (18). Five treatments for the2-year cane cycle were tested: 1) conventionalirrigation water, 2) 12.5-percent effluent dilutedwith irrigation water, 3) 25-percent sewage wa-ter, 4) 50-percent effluent diluted with ditchwater, and 5) effluent the first year and irriga-tion water the second year. Scientists foundthat sugar yields for wastewater concentrationsup to 25 percent, or for wastewater the firstyear and irrigation water the second year, wereequal to those from conventional irrigation sup-plies. When wastewater concentrations in-creased to 50 percent, however, sugar yieldsand juice quality declined significantly. Theresearchers concluded that chlorinated, sec-ondarily treated sewage effluent with nitrogenconcentrations could be used in furrow irriga-tion for the 2-year crop cycle of sugarcane ifwastewater were diluted with freshwater sothat the concentration of effluent was 25 per-cent or less. They cautioned, however, that ef-fluent quality must be constantly monitored fornitrogen content, pesticides, heavy metals, andpathogenic viruses. Such substances in thesoils or waterbodies could prove difficult, if notimpossible, to eliminate (chs. IV and X). In ad-dition, field workers were warned to practicecareful sanitation and personal hygiene to pro-tect against infection.

A second illustration provides a sample ofthe economic questions that surround applica-tion of wastewater for irrigation. Although ef-fluent was generally recognized as a valuableresource for water and nutrients, few farmersactually measured the fertilizer value of thewater. Similarly, those in local governmentsresponsible for the operation of reuse systemsacknowledged the economic value of the efflu-ent but had not established procedures tocharge landowners or farm operators for thevalue that they received. Instead, they took theview that landowners performed a service indisposal of municipal waste effluent.

Third, with regard to social concerns, publicreaction may be an obstacle to wastewater re-use. A survey of selected California commu-nities indicated that respondents favored watertreatment options that protected public health,enhanced the environment, and conservedscarce water (5). However, use of reclaimedwater for ground water recharge and drinkingsupplies was perceived as a threat to humanhealth. Effluent used for industrial purposes orfor irrigation of animal feed and fiber cropswas considered to be an acceptable practice (6).The inconsistency arises when contaminantsfrom effluent reach the ground water second-arily, as the result of its use in industry orirrigation.

Wastewater reuse has been adopted by rela-tively few communities and farmers in theUnited States. It can potentially supplement ir-rigation water supplies and reduce reliance onadded fertilizer, but generates many questions

Ch. Xl—Selected Technologies Affecting Water and Land Management 309

Table 78.—Summary: Issues SurroundingWater Reuse for Irrigation

Resource issues: ‘-

1. Effluent quality:

— N u t r i e n t c o n t e n t

— H e a v y m e t a l c o n t e n t

— P a t h o g e n c o n t e n t

2 . S o i l p r o d u c t i v i t y ”

— S a l t b u i l d u p

— T o x i c i t y b u i l d u p

— V i r a l c o n t a m i n a t i o n— P h y s i c a l d e g r a d a t i o n

3 . C r o p p r o d u c t i o n :

— F e r t i l i z e r a n d w a t e r r e q u i r e m e n t s

— C r o p g r o w t h a n d y i e l d s

— C r o p u p t a k e o f n u t r i e n t s

—Crop uptake of toxics and p a t h o g e n s4 Animal health.

—Animal uptake of nutrients

— A n i m a l t r a n s m i s s i o n o f p a t h o g e n s t o h u m a n

consumers5. Ground water quality

—Path of water to water table—Quality of water reaching ground water

6. Air quality (with sprinkler irrigation)

— H e a l t h e f f e c t s f o r w o r k e r s a n d n e a r b y r e s i d e n t s

— O d o r c o n s i d e r a t i o n s

Social and economic issues:1. Human health effects:

—Contact with effluent by farmworkers–Contact with plant and animal products by

consumers2 Social factors

—Public attitudes toward application—Public attitudes by consumers of products—Attitudes of nearby residents

3. Economic considerations—Water pricing—Transportation costs—Subsidies for those who use water— Facilities for water storage—Value in alternate uses—Type of material contained in water

Institutional issues:1. Water-treatment facilities

—Adequacy and reliability of treatment prior toapplication

—Adequacy of storage facilities during periods ofnonapplication

2. Monitoring—Need for monitoring air, effluent, ground water, crop,

and soil quality3 Legal issues

—Ownership and sale of water—Water rights—Liability for damages—Responsibility for monitoring—Guidelines for water reuse (e. g., crops to be grown,

amount of water to be applied)—Effect on downstream users (third parties), if water

previously was part of return flowsSOURCE William H. Bruvold Agricultural Use of Reclaimed Water unpublished

paper prepared for National Science Foundation January 1982 Off Iceof Technology Assessment, 1982

Table 79.—Crop Yields at Various Levels ofApplication of Wastewater, Pennsylvania

State University— ——.

Wastewater Application Rates.inches per weeka

Crop Ob 1,0 2.0(bushels/acre)

Wheat . . . . . . ... 48 45 54Corn ., . . . . ... 73 103 105Oats . . , . . . . . . . . . . .82 113 88

(tons/acre)Alfalfa . ... . . 22 3.7 51Red clover ., ... . . . . 2,4 4.9 4,6Corn stover ... ... 3.6 7.3 8.5Corn silage ... . . . 4.3 6.4 6,0Reed canary grass ., . . 1.4 — 5.0aMetric units in original document have been converted to English units.bControl areas received commercial fertilizer ranging from 10 tons/acre of

0-20.20 for oats to 40 tons/acre of 10-1010 for corn

SOURCE William E Sopper ‘Surface Application of Sewage Effluent Planningthe Uses and Management of Land Marvin T Beatty et al (eds) (Madison, Wis American Society of Agronomy 1977) pp 633-663 (No21 in the series Agronomy) (Original source U S Environmental Protection Agency, ‘Process Design Manual for Land Treatment ofMunicipal Wastewater, ” EPA 625/1-77-008 (Washington D C 1977) )

on long-term impacts for soil and water quali-ty and, ultimately, public health. Wider applica-tion of reuse systems will require careful plan-ning and monitoring by municipalities and ir-rigators. The costs and danger of handlingwastewater will have to be balanced with eco-nomic benefits of its reuse. In addition, whenapplied on a massive scale, questions are raisedabout the impacts of this water shift on otheraspects of the hydrologic cycle, especiall y

stream flow, if the treated water has previous-} , been part of return flows. Moreover, legalconsiderations for downstream users may becomplex. Much research has been done on thistopic, but additional long-term research on theeffects of these systems on crops, soils, groundwater, and human and animal consumers isneeded. ,

Water Management by Conjunctive Use

INTRODUCTION

The concept of conjunctive use is predicatedon shifts between surface and ground wateruse and storage, During periods of above-average precipitation, or seasons of above-average runoff, surface water would be usedto the maximum extent possible to fulfill vari-ous water requirements. Any surplus water

310 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— .—

would be used to recharge ground water sup-plies and raise ground-water levels. During dryperiods, surface water supplies would be sup-plemented by ground water reserves.

ASSESSMENT

Whether conjunctive management of a ba-sin’s water is technically practical depends onlocal geology and the extent to which groundwater resources are manageable over a rangeof water levels. There must be space to storerecharge water, there must be water in storagewhen and where it is needed, and there mustbe the physical facilities and energy availableto transport surface and ground water.

Management by conjunctive use requirescareful planning to optimize the use of theavailable surface and ground water resources.Detailed, site-specific engineering and econom-ic analyses are needed to determine optimalmixes of surface and ground water storage.

A conjunctive use management approach re-quires more information than is commonlynecessary for the use of either surface orground water resources separately. In the mostgeneral terms, these information requirementsinclude detailed data on surface and groundwater resources, the geologic conditions of thebasin, interconnections of surface and groundwater supplies, water-distribution systems, his-torical and projected water-use patterns, andwastewater disposal practices.

Commonly, except perhaps in the simplestsituation, mathematical models are required todescribe the reaction of the ground water re-serves to fluctuations in natural and artificialrecharge and to varying pumping rates. Suchmodels are available, but they vary widely incapability and limitations and must be usedcarefully. State governments indicate the desirefor more resource models, while the FederalGovernment needs to better coordinate the useof models among various agencies (32),

Ultimately, decisions concerning the feasi-bility of conjunctive use management of waterresources must also include an assessment ofthe relative economic benefits of constructingadditional surface storage facilities, the in-

creased complexity of conjunctive manage-ment approaches, and the cost of energy topump water from aquifers. Because each proj-ect will be unique, no universal rules existgoverning the economics of this approach towater management. Some of the advantagesand disadvantages are listed in table 80.

Enclosures for Plants and Fish

INTRODUCTION

Greenhouses are commonly used in theUnited States to grow horticultural productssuch as flowers and houseplants. In Europe,enclosures are used also for crops primarily ofvery high economic value, such as table vege-tables. In the Middle East and Asia raising fishin enclosures is an ancient applied science.Aquiculture in various forms provides over 40percent of total fisheries production in somecountries but only about 2 percent of totalfisheries products (7).

Many features of arid and semiarid landsmake them especially suitable for growingplants or fish in enclosures: solar energy isabundant, growing seasons are long, and win-ters are often mild, Typically, the efficiencywith which water is used is very high, and in-tensive management allows for the most effi-cient use of other substances such as fertilizersand pesticides.

Plant and fish enclosures vary widely inscale. Some are major corporate enterprises re-quiring large investments to initiate. Others aresuitable for production of a few items forhousehold use and local sales.

ASSESSMENT

Experiments around the world with highlysophisticated systems show that crop yield incontrolled environments is several times thatof field-grown crops. For example, enclosuresin Mexico and Abu Dhabi yielded almost 2 0different fruits and vegetables at productionlevels often several times higher than field-grown equivalents with about one-third the useof water and significantly shorter growing sea-sons.

—

Ch. XI—Selected Technologies Affecting Water and Land— — —

Table 80.—Conjuctive Use of Surface Water and Ground Water Resources

Management . 311—

Advantages Disadvantages—.1. Greater water conservation 1.2. Smaller surface storage 2.3. Smaller surface distribution system 3.4. Smaller drainage system 4.5. Reduced canal lining 5.6. Greater flood control 6.7. Ready integration with existing development 7.8. Facilitated stage development 8.9. Smaller evapotranspiration losses

10. Greater control over outflow11. Improvement of power load and pumping plant use

factors12. Less danger from dam failure13. Reduction in weed seed distribution14. Better timing of water distribution

Less hydroelectric powerGreater power consumptionDeceased pumping efficiencyGreater water salinityMore complex project operationMore difficult cost allocationArtificial recharge is requiredDanger of land subsidence

SOURCE D K Todd, Groundwater Hydrology, 2d ed (New York John Wiley & Sons, 1980) (Original source F B Clendenen,Economic Utilization of Ground ‘Water and Surface Water Storage Reservoirs, ” presentation to American Societyof CiviI Engineers, San Diego. Calif , February 1955 )

Photo credit Food and Agriculture Organization — U. Pizzi

Many types of plant enclosures exist. These plastic tunnels in Malta, protect horticultural crops,such as grapes, vegetables, and flowers

312 “ Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands—

These results are possible because the sys-tems are completely or nearly closed, humidi-ty remains high, and irrigation water is re-cycled. Enclosures also insulate the growerfrom the unpredictable climate of arid andsemiarid regions and help stabilize production,Marketing is also independent of weather, andit can be timed to take advantage of highestprices.

Scientists and engineers continue to refinetechnical aspects of these structures. In the faceof rising energy costs, systems that use solarenergy appear promising for long-term produc-tion. Bettaque (3) described “eco-islands in thedesert” that use solar energy and saltwater toheat and cool greenhouses while distillingfreshwater. He found that such enclosures useminimal amounts of fossil fuel energy, havecapital costs comparable to conventional greenhouses, and that increased crop yields are pos-sible with little technical sophistication. SimilarIsraeli systems use a closed cycle of freshwaterto absorb solar radiation. Practices that maynot be technically possible in open fields, suchas atmospheric enrichment with higher levelsof carbon dioxide, are also being attempted inenclosures (24).

Plant enclosures will not produce largeamounts of inexpensive food because the cap-ital costs for large installations are usually highand operating such enclosures may be labor-and energy-intensive. While basic agronomiccrops grow well in enclosures, they are not ex-pected to be grown commercially in this wayin the foreseeable future. The development anduse of less common types of plant enclosuresface many of the same constraints listed below for aquiculture. For example, most agri-cultural experts are not familiar with integratedplant/fish enclosures or greenhouses, such asattached solar enclosures of unusual design.

Some aquiculture (or a combination of aqui-culture and plant production systems) may bepossible in U.S. arid and semiarid zones, Pre-liminary tests suggest that aquiculture in theWest is feasible (27). For instance, recentresearch in Nevada has shown that shrimp canbe grown in ponds heated by geothermalsprings or by warm wastewater from electric

Photo credit: USDA Soil Conservation Service

The potential for aquiculture in the Western UnitedStates is high. In Texas, these channel catfish have beenseined from a pond and separated from other fish, From

here, they will be transported to a feeding pond

generating plants (30). Several Western Stateshave extensive hatchery and release programsthat could be further developed. Generally, thepotential for aquiculture is rated highly. Thereis an extensive market for seafood in the UnitedStates and more than 50 percent is imported(7). Few aquiculture attempts have been under-taken commercially in the Western UnitedStates, however, and the further developmentof integrated plant/fish and fish systems facessevere constraints. For example, water require-ments for fish culture could be substantial andrequire diversions from other uses. Other prob-lems include:

inadequate funding for research and de-velopment;poor marketing practices;inexpensive imported products;regulatory controls, especially standardsfor waste discharges;

Ch. XI—Selected Technologies Affecting Water and Land Management ● 313.

● uncertain availability of high-quality wa-ter;lack of trained personnel; andovercoming a bad image from past fail-ures.

For these and other reasons, aquiculture isnot expanding rapidly in the United States.Government, industry, and academic expertshave recommended that the United States de-velop a national aquiculture development planand improve coordination of present Federalprograms in order to increase aquiculture’scontribution to fisheries production.

Land Use Management

Most farms and ranches produce one prod-uct and use highly energy-intensive practicessuch as chemical fertilization and pesticides.With uncertain economic and resource condi-tions, such as increasing energy costs andunknown water availability, such specializa-tion may involve greater risks. Therefore, tech-nologies that integrate different types of landuse and different types of agricultural and non-agricultural products hold promise for stabil-izing economic risk and are perceived by someas the direction of the future.

The technologies discussed in this section arediverse and reflect a spectrum of agriculturalphilosophies. For example, multiple land useon rangelands falls within accepted traditionalpractice, but the various types of alternativeagriculture are, by definition, not traditionaltechnologies.

MuItiple Use of Rangeland

INTRODUCTION

Rangelands in arid and semiarid lands arebeing used increasingly by different kinds ofpeople for very different purposes. This is animportant feature of publicly owned range-lands and is required by law for Federal lands.This concept is also being developed for someprivately owned lands. Under these conditions,the highest animal, plant, or water productionper unit area is not necessarily maximized. Forexample, plants that are “unproductive” in

—

agricultural terms may be allowed to remainalong streambanks for the other importantamenities that they provide. When the efficien-cy of water use is measured in terms of allproducts per unit of water used, such multi-ple uses may be more water-use efficient thanwould traditional single uses such as grazing.

Major present multiple uses of rangeland in-clude livestock and wildlife grazing, recreation,and mining. Uses that are less important in-clude harvesting nonforage plant products,such as seeds and nuts, providing militaryreservations and waste disposal sites, produc-ing nonmeat animal products, and producingwater for offsite use.

Al1 of these activities have hydrologic effects,some greater than others. However, the relativeimportance of each potential use and its im-pacts on water resources shift from area to areaand continue to change. In some States, publicrangelands provide a great deal of water-basedrecreation; in others, mining activity is concen-trated on these sites.

ASSESSMENT

Range managers often operate without anadequate data base, making multiple-use man-agement especially difficult. Because Westerngrasslands were altered by human settlementbefore data were collected, major gaps in theunderstanding of the structure and function ofthese areas exist. Early managers did not placehigh emphasis on data collection. Even now,the long-term effects of specific managementpractices are unknown. For example, the re-sults of stocking rates recommended by theBureau of Land Management for individualusers are not systematically monitored.

Intensive management of any resource ismade especially difficult under such circum-stances. The tendenc y is to “maximize” alluses, leading to the nonsustainable use of theresource. Considerable debate has ensued re-cently over the results of applying the multiple-use concept to public range lands, Some con-tend that it wiII diminish the value of publicrangelands for grazing livestock. Others con-tend that multiple use discourages ranchers

25-160 0 - 21 , Q~ 3

314 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— . ——.—. — — —

Photo credit” U.S Department of the Inferior, National Park Service

Federal lands provide a great deal of water-basedrecreation, including fishing, swimming, and boating

from overgrazing and will, in the long term,improve range conditions.

Many factors outside of the agricultural sec-tor determine the future importance of multi-ple uses of all land types. The growing Westernurban population has led to the increase inrecreational use of rangelands. The search fornew energy sources has stimulated mining ac-tivities. Some of these activities are discussedbelow.

Factors Determining FutureMultiple Use of Rangelands

Wildlife.—Arid and semiarid rangelandsprovide habitats for a significant number ofwildlife species, including mammals, birds,and fish. These animals attract large numbers

of visitors to the region and are of great interestto residents as well. Wildlife considerationsstrongly influence water management on manyrangelands, and intensive water managementhas important effects on wildlife. Technologiesfor wildlife management usually do not requireadditional supplies of impounded water butmay result in increased rangeland productivi-ty per amount of water used (21,27).

Wildlife species normally require freshwaterof reasonably good quality. Water consumptionrates are virtually unknown for most wildlifespecies, but they are not thought to be great.For example, total water consumption by biggame animals may range from 100,000 to130,000 acre-ft/year for the entire Westernrange (27). Water distribution and quality aremore crit ical factors. Bighorn sheep areadapted for high water conservation, but theirdistribution depends on available drinking-water supplies. Mule deer populations showmajor changes if the nearest water supply isfarther than 3 miles (38).

Inland rangeland fisheries depend on themaintenance of lakes, perennial streams, ranchponds, and reservoirs. These features also pro-vide habitat for waterfowl, an especially impor-tant rangeland resource in the northern GreatPlains. Water levels must be consistently main-tained for fish and waterfowl to survive. Some-times this is not economically feasible and usu-ally it is not legally required.

Irrigation in the same watershed may lowerwater tables and reduce both streamflow andriparian and upland wildlife habitat. Otheragricultural practices, such as the use ofchemical or mechanical methods to eliminateunwanted plants, alter the cover and foodsupply on which wildlife depend. After con-sidering the major effects that agriculturalpractices can have on wildlife, the National Re-search Council (21) recommended that therebe three requirements for optimizing all re-sources, including water and agricultural pro-duction. These are:

● p r o m o t i o n of attitudes encouragingstewardship of wildlife;

● additional critical research on conserva-tion tillage, irrigation patterns, pesticide

Ch. X/—Selected Technologies Affecting Water and Land Management ● 315— —

effects, and nutrients in aquatic systems;and

c consistent public policies that use incen-tives to enhance fish and wildlife habitats.

Recreation.—Recreational use of rangelandshas increased dramatically in recent years.Much of this activity is water-based, either di-rectly—e.g., fishing—or indirectly —e.g., hunt-ing. Some recreational activities make exten-sive use of shorelines of existing water bodies.Range managers sometimes develop newsources of water from natural seeps, low-yieldsprings, and wells for these uses. These devel-opments supplement and expand water sup-plies on rangelands. However, goals for live-stock production and recreational opportuni-ties sometimes are incompatible and manage-ment is difficult. In Texas, for example, wheredeer and other wildlife are hunted throughleases, ranch managers often give more atten-tion to providing accommodations to huntersthan to actual management of the deer herds(8),

The income from hunting leases to a rancherwith private lands can be substantial. In Texas,where there are few public lands available forhunting and most private lands are protectedfrom trespassing, hundreds of thousands ofacres are leased for hunting each year at pricesof up to $10 per acre (8). Income from leasingin many cases exceeds that from the sale oflivestock, the primary use of the land. Hunterspaid landowners $108 million for leases in 1971(2], and the average cost of each lease has in-creased two to three times since then (21).

Applegate (1) asserts that Texas is represent-ative of other States and that there are ex-amples of ranchers in every State who leasehunting land. In Oregon, where public land isavailable for hunting, leasing arrangements onprivate ranches are increasing. In many areasof the West, though, the lands used for recrea-tion are public lands. Income from hunting per-mits and tourism accrue to the States and localbusinesses, not to ranchers.

Nonforage Plant Products.—Uses and in-come derived from nonforage plant productsare not well documented, but they are signifi-

cant for certain users in certain areas. For ex-ample, seeds are harvested in some areas forrange reseeding, mineland reclamation, and ur-ban horticultural use (fig. 73). Some seeds maybring prices as high as $8/lb (12).

Pinyon pine nuts have been a staple foodsource for American Indians throughout theintermountain States. The few nuts reachingurban markets are prized, Potential exists formaximizing production of native stands andalso harvesting nuts from areas unsuitable forany other crop. Some range plants have poten-tial as biomass fuel sources (see ch. IX for adetailed discussion). Other potential plantproducts include wooden jewelry and fibers forbasketry and paper. These activities will prob-ably continue and may increase in the face ofdeclining water supplies for other uses,

Nonmeat Animal Products.—The produc-tion of many nonmeat animal products, suchas fur, wool, and hides, can increase substan-tially without seriously affecting water re-sources, Since most produced now are notsold, their sale would represent an increase inagronomic water-use efficiency. See the discus-sion on animal mixtures, below,

MULTIPLE-USE TECHNOLOGIES

The multiple-use concept has been instru-mental in shaping technology development andadoption for rangelands, Two examples follow,one in which technology developed for themining industry is moving into agriculture andone in which agricultural technology was re-fined by multiple-use demands,

Surface-Mined Land Reclamation

Introduction.— Mining activity is wide-spread on Western rangelands and on somecrop and pasturelands. Coalfields in Montana,Wyoming, North Dakota, South Dakota, Utah,Colorado, New Mexico, and Arizona underliemore than 100 million acres. Approximately 9 0additional minerals are found in sufficientlylarge deposits to be mined,

Mining activities influence water in manyways. Water that flows through a mining areamay be degraded in water quality, a conse-

316 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— —

Figure 73.—Summary Information for Using BigSagebrush in Rangeland Reclamation

Big Sagebrush (Artemisia tridentata)

Characteristics

Height:Spread:

Growth form:

Root-system type:

Habitat

Distribution:

Elevation:Topography:

Salt tolerance:Drought tolerance:

Soil:

Use

Forage value:

Erosion control:Landscaping:

Propagation

Seed:

Vegetative:

1.5 to 9 ft (0.5 to 3 m)1 to 5 ft (0.3 to 1.5 m)Round, generally erect, multi-branched, evergreen shrubDeep, spreading

Nebraska to eastern California,south to New Mexico, Arizona1,500 to 10,600 ft (495-3,500 m)Wide spread, low-elevationrangeland to mountain slopesFairGoodFine- to coarse-textured, acidic andbasic, moderate to deep, welldrained

Important for wildlife on winterrangelandControl mass-soil slippageGray-green foliage

Good germination at roomtemperature but is speeded at coolertemperatures: seeds ripen lateSeptemberCollect stem cuttings Feb. to April—treat with 2.0°/0 IBA powder

SOURCE Institute for Land Rehabilitation, Select Ion, Propagation, and FieldEstablishment of Native Plant Species on Disturbed Arid Lands,Utah Agricultural Experiment Station Bulletin 500, 1979

quence of the mining process (ch. IV). Substan-tial water supplies may be required during min-ing operations and stream widening. Lakedrainage, surface-flow diversions, streambankdisruption, and ground water interference mayall occur. Collectively, mining activities affectwater supplies and the use of the land for agri-culture.

Mining also has indirect effects on water use.Surface mining destroys existing natural com-munities completely and dramatically. Becausewater is the major factor in revegetating theseareas, many reclamation efforts focus on wateruse and management.

Assessment .—Most ar id and semiar idrangelands have not and will not face suchdrastic disturbances. Probably only a smallpercentage of all rangelands will be surfacemined for coal. Yet water remains the key tomaintaining or restoring rangeland productivi-ty. As a result of these similarities, many rec-lamation technologies can be used directly onother rangelands. This is important becauseCongress has mandated improving the condi-tion of the 160 million acres of public range-lands in the 17 Western States and recent leg-islation* established a national commitment tomaintain and improve public and privaterangelands, making them as productive as fea-sible for all rangeland values. Until now, suchimprovements were slow and few technologiesexisted.

Reclamation technologies are not expectedto increase agronomic water-use efficiency ofplants or animals greatly, but preliminaryresearch suggests that some gains can be made(27). A variety of technologies are possible:

c water-retention methods to speed plantestablishment and minimize runoff,

● plant breeding for hardy and palatablegrasses,

● planting and seeding technology,● soil building techniques, and

— —.* Forest and Rangeland Renewable Resources ~lanning Act,

(public Law 93-378]; Public Rangelands Improvement Act,(Public Law 95-514).

—

Ch. Xl—Selected Technologies Affecting Water and Land Management ● 317— —. . —

● management of vegetation compositionand ecosystem analysis.

Dryland sodding is an example of a technol-ogy to prevent erosion and to establish plantcover rapidly. With this technique, thickly cutnative sods containing grasses, forbs, andshrubs are placed on steep, erosive slopes andspecial machines have been developed to han-dle native sod efficiently and effectively.

In the past, rangeland managers avoided theuse of many potentially useful plant species onundisturbed lands owing to problems with seedsize and shape, low germination, or seedlingvigor. Because regulations require large pro-portions of native plants in reclaimed areas,new planting and seeding technology was stim-ulated. Special techniques and equipment nowexist for harvesting, treating, and planting fuz-zy, awned, sticky, minute, or otherwise trouble-some seeds. In some cases, the vulnerable seedand seedling stages are protected by speciallydesigned containers or underground stem androot transplants are used in revegetation effortson marginal or “impossible” sites.

The productivity of some undisturbed rangesites is limited by soil conditions—e. g., highsodium or clay content—that affect nutrientand water availability as well as toxicity toplants. Surface mining requires the completereconstruction of soils. Therefore, reclamationresearch has stimulated the development of soilbuilding technologies that have the potentialfor transfer to other lands. These include theuse of biological, chemical (organic and in-organic), and physical amendments to the soil.

Most surface mining regulations have rigidrequirements for determining the success ofreclamation. In some cases, the compositionof vegetation is specified. As a result, interesthas increased in vegetation management meth-ods as well as in long-term ecosystem analysis.Some management methods, such as rangelandfertilization, burning, irrigation, interseeding,and grazing, were developed for undisturbedrangelands but are being refined by reclama-tion efforts. Others, such as long-term analysesof plant/environment interactions, are seldom

—

matched in duration or intensity by traditionalrangeland research (25).

Legal, social, political, economic, and cultur-al factors may be barriers to implementationof reclamation technologies on undisturbedrangelands. For example, Federal law on theuse of native plants and land with agriculturalpotential has affected State regulation and re-search. Schechter (24) maintains that R&D areinadequate and that capital does not exist tomeet this need, A single discipline focushinders application of the research that hasbeen done. For example, undisturbed range-lands may contain more than 40 plant species,but revegetation efforts often focus on a singlespecies. Moreover, there is a general lack ofunderstanding of soil biota. More informationabout complex multiple species interactions isneeded, a task requiring an interdisciplinary

effort.

Economic return varies widely among West-ern agricultural land uses, making certaintechnologies suitable for some lands but not forothers. For example, private companies mayspend $2,500 to $6,000/acre to reclaim land thathas been surface mined for coal (14). A near-by acre of undisturbed land may sell for $200.Clearly, reclamation is costly, even whendisturbance is less drastic than that from sur-face mining. Improvement of unmined but de-graded public rangelands using a variety oftechnologies would represent a major econom-ic investment. The Bureau of Land Manage-ment has a backlog of $34.7 million in neededrange improvements, and the cost of additionalprojects is estimated to be over $148 mil-lion (37).

Management of Undesirable Plants and Animals

Introduction. —Range managers identify anumber of plants that decrease livestock forageor have other undesirable features. Some ofthese plants are not natives of the West buthave spread after introduction from other partsof the world. Undesirable plants maybe highlyadapted to arid and semiarid conditions andtherefore difficult to remove once established.

318 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands

Photo credit: USDA-Agricultural Research Service

The Range Improvement Machine is being developed by USDA/ARS in cooperation with Montana State University for useon semiarid rangelands and marginal pasturelands to increase grass and forage yields. It uses a packing wheel system.

For purposes of water conservation, the gap in each wheel leaves a check dam at 7-ft intervals (inset)

Ch. Xl—Selected Technologies Affecting Water and Land Management ● 319—.

The definition of plant pests depends on theintended land use and the specific site, butplants such as mesquite, oaks, and sagebrushare often considered to be undesirable byranchers.

Human use of rangelands has exacerbatedthe increase of plants considered undesirable.Intensive grazing, the exclusion of fire, andtemporary cultivation have changed the com-position of plant communities. Invasion ofwoody species also decreases the availabilityof forage for livestock and is the primary causeof rangeland degradation. Therefore, technol-ogies to control “brush” are one way to in-crease rangeland productivity. Usually, largeamounts of water are not directly involved inthese technologies. Instead, increases in pro-ductivity lead to higher water-use efficiencies.Other applications of these technologies maybe made to increase water runoff specifically(ch. VI),

In some parts of the West, principally in pub-lic rangelands in Utah and Nevada, wild horseand burro populations also degrade lands. Ex-

—. —

perts estimate that 60,000 to 70,000 wild horsescompact soils, overgraze plants, and general-ly interfere with careful rangeland manage-ment and optimal use of forage. Programs tocontrol these and other animals are used toachieve three management objectives: 1) pro-tect livestock, 2) reduce the number of her-bivores that compete with livestock for avail-able forage, and 3) protect the range from over-grazing and subsequent damage to productivi-ty. Most control programs seek to optimizepopulation size, not to e l iminate all w i l danimals.

Assessment .— Studies o f severa l p lantspecies indicate that control or removal signif-icantly increases soil water, resulting some-times in a concomitant increase in availableforage for livestock. However, not all standsof undesirable plants use large amounts of wa-

ter that would be available to other users, andthe amount of water affected depends on theoriginal type of vegetation, its density, local

precipitation, and the control method used. Insome cases, vegetation considered by ranchers

Box Z.—Integrated Brush Management: A New Approach for Degraded Rangelands

In the last few years, emphasis in range management has shifted from eradication of noxiousplants to their careful control by combinations of methods, known as integrated brush manage-ment, The basic principles include:

reducing dependence on any single control method,using the synergistic effects from treatment combinations,increasing both livestock and wildlife habitat,developing flexible treatments for different conditions,integrating treatments with other management techniques, andenhancing economic returns from brush management.

These techniques are applicable to most sites, but to be successful they require long planninghorizons: brush-management systems are designed to span 15 or 20 years. These program are ex-pected to be adopted first in areas that have major brush problems. For the next decade, Texas,Oklahoma, and New Mexico will probably be most involved. Adoption could increase rapidly ifcosts of other range-management technologies or Federal constraints on herbicide use increase.

The costs of these techniques vary widely, and there are additional indirect costs and benefits.primary constraints to implementation are economic, especially for the first costly step in a se-quence. Technical constraints are significant since research still is in the formative stage and treat-ment testing requires long time periods.

SOURCE U.S. Congress, Office of Technology Assessment. Impacts of Technology on U.S. Cropland Rangeland Productivity (Washington, DC: US GovernmentPrinting Office, OTA-F-166, August 1982)

.— —.

320 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands—

to be undesirable provides important benefits.For example, most stands of trees and shrubsfurnish wildlife habitat. They may also provideshade for livestock, protect soil from wind orwater erosion, increase water runoff for offsiteuses, or contribute to the attractiveness and di-versity of arid and semiarid lands.

Each of the common brush-control technol-ogies has advantages and disadvantages. Me-chanical control is labor- and energy-intensiveand thus expensive. After chopping and clear-ing plants, some residue usually remains,which is advantageous, but considerable soildisturbance also occurs. Chemical control isspecific, effective, and often less expensive, butsome chemicals, improperly applied, maycause crop damage or health hazards. Regula-tions largely prohibit chemical use on Western

——.——

Federal rangelands. In contrast, fire, always afeature of Western rangelands, is gaining ac-ceptance as a major control technology. It isinexpensive, but all areas cannot support firesand the resultant denuded ground is subject tosoil erosion.

These conventional control technologieshave been criticized for being used withoutregard to their effects on values other thanlivestock production. Integrated brush manage-ment is a newer technology that has the poten-tial for enhancing multiple-use values of range-lands. Some experts contend that this technol-ogy can make a large contribution to increasedwater availability for agriculture on range-lands,

With an integrated approach, it is possibleto manage noxious plants for their potential

Photo credit: USDA-Soil Conservation Service

Fire is gaining acceptance as an effective brush-control technique. Here, junipers are ignitedto increase forage production on rangeland in Arizona

Ch. XI—Selected Technologies Affecting Water and Land Management . 321

benefits. For example, because mesquite mayform very dense stands, and cattle sometimeshave difficulty digesting mesquite pods, mes-quite is often considered to be noxious. Butthese trees have traditionally been used forfood, forage, and firewood production bySouthwestern Indians who considered mes-quite’s importance greater than that of cornand wheat. Unripened and ripened pods andseeds were eaten by humans and animals, andthe wood continues to be prized. There is evi-dence that selected varieties of mesquite couldbecome nitrogen-fixing, low water-using cropswhich require little or no tillage (11), Bigsagebrush is also commonly regarded as a nox-ious plant because it is aggressive and unpal-atable to domestic livestock. For these reasonsit has been the target of widespread eradica-tion programs. An alternative approach wouldbe to use the richly variable germplasm baseto improve the species’ forage qualities.

An integrated management approach canalso be used for noxious animals, but wildhorse and burro control represents a particular-ly difficult problem. These animals are withouteffective predators and are capable of rapidpopulation increases. They can inflict heavydamage on rangelands. Both offsite and onsiteeffects on water resources have been noted butnever quantified (20). Transplanting animalsis only a temporary solution, fertility-controlwith drugs is expensive, and selective killingis sometimes strongly opposed by the public.

Animal Mixtures on Rangelands

INTRODUCTION

Different animals have different food pref-erences, i.e, they consume different plantspecies, different parts of the same species, andthe same plant parts growing at differentheights. Therefore, mixtures of animals useresources more fully than any one species.When species more adapted to dry conditionsare included, they may also use resources moresustainably.

. —

ASSESSMENT

Some experts feel that animal productivitycan be increased by stocking rangelands withmore than one kind of animal (10). For exam-ple, new combinations of livestock and wildlifespecies could double range productivity insome areas, and an optimal grazing manage-ment scheme for shortgrass range sites mightallocate forage to cattle (67 percent), bison (20percent), sheep (12 percent), and antelope (1percent) (17). Sheep and goats graze over widerareas and rougher terrain than do cattle, Usedin combination, they could control brush andweed invasion resulting from overgrazing bycattle.

Few range managers have attempted opera-tions of this complexity. Ranchers with privatelands—e.g., in Texas—have the most ex peri -ence with large mixtures of animal species.These mixtures usually include unusual exoticanimals that are stocked for recreational hunt-ing or photo safaris, not for large-scale meatproduction. This concept awaits full-scale test-ing with North American game and domesticanimals.

Optimal combinations of herbivores can onlybe determined if the diet-selection process isunderstood. Currently, no models exist that candefine this process and it is not possible topredict dietary or spatial use of any given site,The limited numbers of experiments withmixed-species grazing systems do not provideinformation on their long-term effects. For ex-ample, little is known about the effects of suchsystems on overall efficiency of energy use orof nutrient cycling. Furthermore, little isknown about the effects of larger numbers ofsheep on populations of big game animals.

When more than one species of animalgrazes an area, it is critical to match demandto available vegetation. Overlapping plant pref-erences could destroy a plant species beforethe process is apparent in declining animalhealth or numbers. Innovative approaches areneeded to study the responses of mixed animal

322 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands— —.-——

Box AA.-Alternative Agriculture in Arid/Semiarid Lands: The Innovators

It maybe decades before alternative agriculture is practiced widely in arid and semiarid lands.Pioneers are at work now, and it may be their work that shapes the future of American agriculture.

Workers at the Land Institute in Salina, Kans., are developing a grain-producing system thatmimics the diverse and productive grasslands which once flourished on the Great Plains. Theyuse perennial plants to decrease tillage and erosion; legumes and quickly decomposing compositesto cut fertilizer needs; and unusual germplasm to increase nutrition and seed yield.

Cooperative studies between botanists at the Arizona-Sonora Desert Museum (Tucson, Ariz.)and the University of Arizona explore the potential for crop mixtures of short-lived desert plantsand perennials. Native plants such as mesquite, tepary beans, gourds, devil’s claw, and cacti areblended with biological technologies for fertilization, pollination, and soil-water absorption.

The Agroecology Program at the University of California, Santa Cruz, focuses on research andsmall-scale field trials of new systems. Experiments include ones on integrated pest management,pollination, multiple cropping, the use of fire in agriculture, trees as crops, farm pond aquaculture,and comporting. Part of this program is tailored to students, but it also includes cooperative proj-ects with local farmers and extension agents.

Rodale Press has been a leader in the alternative agriculture movement and, with the establish-ment of the Rodale Research Center, it produces careful and credible agronomic research. Thiscenter, especially through its work with grain amaranth, is now working more with crops for drylands. A new consulting role in foreign arid lands can be expected to strengthen these aspectsof its program.

species on different types of range sites, espe-cially where sustained productivity of wild anddomestic species is the goal.

The combination of domestic livestock—e,g.,sheep and goats with cattle—has not been prac-ticed extensively, The sheep and goat indus-tries are both relatively small, providing alimited market for new technologies and con-straining innovation, The sheep industry, aftera sharp decline due to low returns, high laborrequirements, and losses to predators, seemsto be at the beginning of a modest recovery ow-ing to increasing competitiveness of naturalfibers. Both sheep and goat producers facestrict regulations that favor cattle producers,

Alternative Agriculture

INTRODUCTIONThe predominant agricultural systems used

in the arid and semiarid parts of the UnitedStates represent a fraction of the kinds of sys-tems available worldwide. Present systems arelargely based on frequent tillage; the use of a

few, very specialized, annual crops; and addi-tions of large amounts of added synthetic fer-tilizers and pesticides. While these systemspredominate, some Western farmers do not usethem.

Some farmers and ranchers are experiment-ing with types of agriculture that are quite dif-ferent. These new systems are diverse and mayinclude complex mixtures of crops in one field(polyculture or intercropping); they may in-clude perennial grains or tree crops instead ofannuals such as corn, sorghum, and wheat(perennial polyculture or permaculture); orthey may eliminate synthetic pesticides andcommercial fertilizers (organic farming), Gen-erally, they rely heavily on natural biologicalprocesses, such as nitrogen fixation by leg-umes, instead of artificial replacements, likefertilizers (table 81),

ASSESSMENT

Such alternative agricultural systems havedemonstrated their usefulness under certainconditions. Some scientists observe their in-

Ch. Xl—Selected Technologies Affecting Water and Land Management ● 323— — —

Table 81 .—Examples of Human Substitutions for Biological Processes

Biological process displaced Non biological process substituted

Natural fertilization in plants/seed dispersal Plant breeding/harvesting of seedsFixation of atmospheric N by bacteria Application of artificial nitrogenous fertilizersExploration of soil by roots for potash and phosphorus Application of artificial fertilizers; irrigation

and waterNatural control of pests and weeds Use of pesticides and herbicidesCollection of feed by animals Harvesting, processing and automated provision of

compounded feed; forage conservationGrazing Zero-grazing (the cutting and carting of herbage)Natural deposition of excreta on the land Collection of excreta from housed animals and its

disposal, treatment or distribution on landIncubation of eggs by hen birds Artificial incubatorNatural service by male animal Artificial inseminationNatural hormonal processes Control of light, day-length and temperature; use of

synthetic hormonesNatural suckling (of calves and lambs) Artificial rearing on milk substitutesNatural immunity to disease in animals Use of vaccinesUse of animal power Use of machines and fossil fuel

SOURCE C R W Spedding J M Walsingham and A M Hoxey. Biological Efficiency -in Agriculture (London, U K Academic Press, 1981)

creasing credibility and expect that they willassume greater importance in the future (23).The advantages claimed for these systems aremany and include lower use of expensive, fos-sil fuel-based chemicals that may be hazardousto human health and the environment, im-proved soil structure and better growing con-ditions for plants, less soil erosion, a morediversified and therefore more stable agricul-tural base, more nutritious agricultural prod-ucts, and more efficient use of natural re-sources.

Some of these claims have been substanti-ate]. For example, farms producing a varietyof products generally reduce their risks and in-crease the effective use of total resources. Poly-cultures of plants grown together, in contrastto monoculture of one plant, may use soil nu-trients more eff iciently, increase economicreturns, improve the nitrogen status of cropswhen legumes are part of the mixture, and pro-vide stability of yields over time (16). Systemsthat eliminate synthetic chemicals also elim-inate the possibility of pesticide contaminationand minimize contamination of ground waterand runoff from commercial fertilizers (21).Organic farming has been shown to increasewildlife populations and in at least one WesternState, the U.S. Fish and Wildlife Service recom-mends it for producing crops for wildlife (29).Other claims, such as the effects of organic

farming on crop nutrition, are less well under-stood and many need further research.

The earliest advocates of these technologiesbased their arguments on ideological groundsor on the perception of severe environmentalproblems resulting from traditional agriculturalpractices, More recent practitioners are adopt-ing alternative systems on economic grounds,For example, most of the cornbelt/Great Plainsorganic farmers surveyed by Strange (29) citedthe importance of lower production costs andinsulation from rising variable input costs,One-fourth of these farmers borrow no oper-ating capital. Many of these people also sharea belief that farmers and ranchers should notexhaust the natural resources on which thefuture of agriculture depends. For this reason,they feel that alternative agricultural systemsare among the most forward-looking and re-source-conserving of technologies under devel-opment.

Both basic and applied research on alterna-tive systems have been limited. This researchis not simple: controlled experimentation is dif-ficult, no one type of alternative agriculture isrepresentative, and the benefits claimed to ac-crue may take decades to manifest themselves.Public and private investment in research issmall. For example, USDA formally decidedto terminate research in this area contrary to

324 “ Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands. — — . . — - — . - — — —

the results of its own study (35), Interestedfarmers have had few places to get informa-tion. One survey of organic farmers showedthat only 5 percent sought or received helpfrom land grant universities and only 3 percentcould find assistance from extension agents(29). A more extensive foreign data base existsfor some technologies, such as the polyculturesof India, France, and Africa, but this informa-tion generally has not been adapted for use inthe United States.

Research is lacking also on alternative sys-tems for arid and semiarid lands, For exam-ple, most research on organic farming has beendone in humid regions of the United States.Polyculture systems, such as those extensive-ly used in India, are more common in arid re-gions and they generally perform better in dryseasons. But claims that polycultures use watermore efficiently or are able to tap water un-available to monoculture have not been sub-stantiated. For these reasons, it is impossibleto predict under what site-specific circum-stances polyculture will prove to be advantage-ous.

This lack of information has contributed toan absence of organizations to assist producerswith questions and problems related to alter-native agriculture. The people who are in-terested in many of these systems generally arenot part of the traditional agricultural commu-nity and are not well organized among them-selves. Therefore, knowledge of alternativeagricultural systems has had limited accepta-bility and visibility. There is evidence that thetendency to dismiss new systems as impracti-cal or bizarre may be declining. For example,under a congressional mandate*, USDA com-pleted its first study of organic farming in 1980,and the University of Nebraska holds an an-nual organic farming field day. Large numbersof farmers continue to express their interest inalternative methods despite the lack of officialencouragement.

It is not clear yet to what extent these tech-nologies will be applicable to farms or ranches

‘Section 1461 of Title XIV of the Food and Agriculture Acto f 1977 (J’ub]ic Law 95-1 13).

of varying sizes and in different geographiclocations. Most of these systems are highly in-tegrated and require good management skills,substantial knowledge about plants and ani-mals, and marketing expertise. The need forthese skills may place low limits on the size andscale of a particular enterprise. While the pro-ductivity of some farming systems maybe highper unit of land, the labor intensiveness maymake productivity per farmer or rancher rela-tively low.

There is no consensus whether these systemswould produce, in the near term, yields as largeas those currently achieved. For example, someexperts feel that the widescale adoption oforganic farming would result in lower, but ac-ceptable, total productivity (4). Other results in-dicate that adoption of organic farming prac-tices might actually increase farm unit produc-tion by decreasing operating costs. The greatestbenefit of these systems is in sustaining or im-proving inherent land productivity, This ben-efit could compensate for short-term yieldreductions if they materialized (33).

Multiple Use of Croplands

INTRODUCTION

Rangeland uses for recreation and wildlifeare important adjuncts to meat production inmany areas. Similar multiple uses of croplandare possible, and some farmers are actively pur-suing this option. In fruit, nut, and vegetablegrowing areas, some farmers invite customersto pick their own produce. Farmers may pro-vide other services, such as hayrides to fieldsor samples of processed produce. Managementof some areas emphasizes, for the visitor, therecreational aspect of the visit,

Grain-growing areas provide important wild-life habitats and some States allow leasing themfor hunting. In Texas and California especial-ly, irrigation and cultivation practices cansometimes be managed to increase wildlifehabitat. The large pheasant and waterfowlpopulations that often result provide an oppor-tunity for farmers to lease land at attractiveprices.

Ch. XI—Selected Technologies Affecting Water and Land Management ● 325— - — .-. . . —— — —

ASSESSMENT

It is difficult to assess either the present orpotential role of multiple uses of cropland. Nocentral source of information exists on theseland uses. For some areas, though, it is clearthat wildlife and hunting uses of cropland arehaving a large economic impact.

Wildlife in many areas have suffered fromrecent agricultural practices. Fencerow-to-fencerow cultivation, removal of grain stubble,intense grazing of pastures, and extensiveweed and pest control have adversely affectedwildlife. These practices partly reflect the drivefor higher agricultural production and partlythe feeling that wildlife is a farm liability. Thusin some areas, recreational use of cropland isunlikely in the face of negative attitudes. Hunt-ing on croplands is also limited by farm sched-ules. Hunting season may occur during harvestor other busy times when it is not practical tohave visitors in the fields.

In other areas, agricultural practices haveenhanced wildlife, and farmers have welcomedand used this increase (table 82). In SouthDakota, small-game hunters purchase a $5wildlife stamp in addition to their huntinglicenses. The revenues generated are then paidto landowners for the maintenance of pheasantnesting cover. More than $500,000 was paidin 1979 to farmers at an average rate of $22/acre. After 5 years in operation, 535 land-owners are involved and about 15,000 acres ofcropland have been diverted for wildlife pur-

Table 82 .—Gross Revenue to Western Statesa FromHunting and Fishing Licenses in 1981

State Hunting licenses ($) Fishing licenses ($)

A r i z o n a . , . , — 3,585,167C a l i f o r n i a 7,005,827 24,156,555Colorado. . . . 18,370,746 5,436,643Idaho ., ., . . 5,322,771 3,100,745Montana ., ., ., 4,688,759 3,797,090Oklahoma ., . . . . 4,564,625 4,144,402Oregon . . . . 7,543,558 6,408,517Texas . . . 6,314,663 7,406,271Utah . . . ., 5,598,120 5,129,323Washington . . 5,867,014 6,704,656Wyoming . . . 10,919,365 —

aStates included rank among the top 25 in the United States in terms of Staterevenue from these activities

SOURCE U S Department of Agriculture, Soil Conservation Service Texas Con-servation TIPS, December 1982

poses (l). Some wildlife species do not benefitfrom such programs: in areas in which landconversion among rangeland, cropland, andpastures occurs, only those animals adapted tochangeable conditions are favored,

Set-aside programs for wildlife are expensiveto the organizers and may not encourage wideparticipation. The multiple use of farmland,therefore, depends on strong economic incen-tives for individual farmers. This is the casewhen croplands are leased for hunting. In Tex-as, for example, farmers are being encouragedto consider pheasants as a cash crop and toplan management decisions to accommodategamebirds. By planting wheat, sorghum, andcorn to provide cover and food in proximityto water, farmers can enhance pheasant pro-duction. Ponds that capture irrigation waterrunoff also have become prime pheasant hab-itat where farmers can encourage the growthof important gamebird vegetation. Duringhunting season, these practices translate intoleases to individual hunters or sports clubs ata minimal cost of $25/person/day or $125/per-son for the season’s opening weekend (28).

In Texas and other States where irrigationhas changed the face of agriculture, the avail-ability of water supplies may determine the fu-ture of both agriculture and wildlife. Chang-ing water use in the Central Valley of Califor-nia has had major effects on wildlife and hasmade hunting an important use of irrigatedland. In many cases, the changes in in wildlifehabitat or populations inadvertently accom-panied changes in agricultural technology.

Table 83 shows some of the more general in-teractions between technological changes andresources in the Sacramento Basin of Califor-nia. Specific changes may also be traced. Infewer than 100 years, about 5 million acres inthe Central Valley were converted from grass-lands, marshlands, and waterways to high-val-ue farmland and urban areas. As a result, anumber of species of waterfowl have becomedependent on cultivated cereal crops, whereasother species dependent on the natural vegeta-tion have declined. Pastures and fields of corn,rice, mile, wheat, and barley provide habitatfor large numbers of migratory and resident

I

Table 83.— Relationships Between Agriculture Practices and Fish and Wildlife, Sacramento Basin and Delta-CentralSierra Hydrologic Study Areas

Opportunity Agricultural viewpoint F i s h - w i l d l i f e - r e c r e a t i o n v i e w p o i n t

P r a c t i c e f o r w a t e r s a v i n g P o s i t i v e N e g a t i v e P o s i t i v e N e g a t i v e Comments

One of two truemeans of savingwater in basins

Increase groundwater pumpage

Possibly very large

Moderately large

Farmers gainoperating inde-pendence and dry-year flexibility

Increased dry-yearsupply

High initial cost;big energy user

Reduces diversionsfrom river

May increase per-colation

Increase reservoirstorage

None Decreases peakflows; increasesdry-year summerflows; enhancesreservoir-typefisheries

Would tend toreduce diversionsfrom the Sacra-mento River, leav-ing more water forin-channel use

Would flood outnative lands

Opportunity fortrue in-basinwater savings

Reduce water ap-plied to rice

Large, possiblyseveral hundredthousandacre-feet

Should produce alarge net saving inapplied water use;save energy andfertility

Would increase ir-rigation manage-ment costs; in-crease TDS ofdrainage water

Would decreasedrain flows,hence diminishriparian vegeta-tion and fishflows, increaseTDS and watertemperatures

Elimination ofberms would re-duce wildlifehabitat

No savings wouldresult unlessstorage provided

Level all rice pad-dies, form rec-tangles

Included above Would decrease ap-plied water use byan estimated 5%;

i n c r e a s e y i e l d ,

r e d u c e w a t e r m a n -

a g e m e n t a n d h a r -

v e s t c o s t s , i n -

c r e a s e n e t p r o f i t

W o u l d r e d u c e w a t e r

u s e ; i n c r e a s e f o r -

a g e p r o d u c t i o n

Would take landout of produc-tion for one cropyear; requirecapital outlay

Included above Now catching onrapidly in rice-growing areas

I

Drain wet moun-tain meadows;improve watermanagement

Small Would require an-nual mainte-nance cost; highoriginal invest-ment

None Would reducewetland habitatreduce late sum-mer downstreamflows

As time goes on,practice will beemployedthrough the in-centive to in-crease forageproduction

Must developincentives fordistricts to takeaction; must per-suade peoplethat water-savingpractices arenecessary

I

District practices;canal lining (re-duce seepage);

Large, could re-duce district de-mands

These practices willdecrease water de-mands on a dis-trict basis; couldincrease yields anddecrease fertilizerneeds

Would require None Would reducewetland habitat.reduce fishflows, raise wa-ter temperatures,increase TDS,concentratepesticides, andincrease channelvelocities insome areas

more energy,capital, and man-power, increasethe unit cost ofwater, leavedrain waterusers with noavailable supply

increased use ofrelift pumps,control ditchbank vegetation,clear channels

SOURCE State of California, Department of Water Resources Bulletin No 198, May 1976—

.— .— —. —

Ch. Xl—Selected Technologies Affecting Water and Land Management ● 327. ..- . — — — . .

waterfowl. In some parts of the valley, farmerscan realize significant economic returns fromleasing hunting rights. These farmers mayflood cornfields and create wetlands insteadof planting a second crop to increase water-fowl populations, In some cases, this practicealso removes salts that have built up in the soilfrom previous irrigations. A large number ofduck clubs now makes use of these croplands.For example, at least 84 private duck clubs existin San Joaquin County, Calif., and about one-third, or 12,000 acres, of the land leased forhunting represents flooded fields.

In other areas, irrigation water is becomingless available, and careful management isundertaken. For example, where rice is grown,land leveling—the use of fewer levees betweenfields—and more productive rice varieties haveincreased yields but decreased both cover andfood for wildlife. In these areas, wildlifepopulations have declined. Some experts feelthat the situation is becoming critical. Greaterpressures for careful irrigation managementare driving farmers to use less water, and theycannot be expected to continue to sustain largewater-dependent wildlife populations.

Computers and InformationManagement

Inroduction

Ranchers and farmers manage informationdaily, Decisions regarding which crop to plantor when to sell livestock, for example, are basedon obtaining and evaluating information froma variety of sources. The availability of elec-tronic computers has changed the nature of in-formation management, and computers arerapidly becoming everyday tools in agriculture.

Agricultural scientists have used computersfor research analyses for some time. The directavailability of computer-assisted analysis toranchers and farmers is more recent. Compu-ters are having an impact in two differentways:

1, university/State extension services areproviding access to large, shared com-puting facilities through networks of ter-minals; and

2. producers are purchasing microcomputersfor home use.

The large computer systems share centraldata storage and processing facilities. The Agri-cultural Computer Network (AGNET) is a goodexample. AGNET was developed by Universityof Nebraska scientists in the 1970’s and ex-panded into five Western States on a pilot basisin 1977. As of 1980, six States are full partnersin the operational system: Montana, Nebraska,North Dakota, South Dakota, Washington, andWyoming. AGNET relies on a large centralcomputer in Nebraska and the backup skills ofnearly 20 computer specialists in the partici-pating States. Extension Service offices and in-dividual users gain access via local terminalsto program libraries. These terminals can beas simple as touch-tone telephones or as elab-orate as nonportable terminals with videoscreens and printer attachments.

AGNET was designed to be a tool for mak-ing farm and ranch management decisions andfor providing up-to-the-minute market newsand extension information. Over 200 agricul-tural programs are available now to users andit is considered to be the best system availableto farmers and ranchers today. Programs in-clude ones for cattle production, tax planning,machinery costs, home food preservation, ir-rigation scheduling, and soil loss. Farmers andranchers are often included in planning theseprograms to ensure their usefulness.

Microcomputers (also called home or person-al computers) can provide some of the samefacilities. These units often have a keyboard,a video or television screen, magnetic data andprogram disks and disk drives, and a printer.They are self-contained and often users rely onprograms developed for their particular ma-chine. Farmers and ranchers use these smallsystems for business accounting as well as forstoring and analyzing records of herd perform-ance. Some microcomputers have graphicsprograms for displaying the results of analyses,Telephone couplers allow microcomputers tobe used as terminals and provide access to thelarge computer systems.

328 ● Water-Related Technologies for Sustainable Agriculture in U.S. Arid and Semiarid Lands

Assessment

Some experts predict that computers will be-come commonplace during the 1980’s and thatthe farmers and ranchers who do not use thesemanagement tools will be out of business by1990. Computers make recordkeeping moreprecise and can help prevent management er-rors. Both of these elements are crucial whenprofit margins are low and prices fluctuatewidely.

Farmers and ranchers with timely access tolarge systems such as AGNET can use elabo-rate computer technology at minimum person-al cost. They can use tools that were specifical-ly designed for agriculture and many that weretailored to conditions in the West.

Costs for direct terminals into large systemssuch as AGNET vary from minimal monthlytelephone rental charges to $7,000 for the mostelaborate purchased ones, Several small port-able terminals cost about $1,500. Also, userspay long distance charges for the time duringwhich the computer link is actually made.These charges may increase operating costs be-yond the initial purchase price of the micro-computer. Purchase and operating costs areusually borne by universities and cooperativeextension services in order to make terminalsavailable in county offices and for specialiststo use for local demonstrations, Some exten-sion offices supplement large computer sys-tems with microcomputers and are developingspecial agricultural programs for them. For ex-ample, Utah State University is developing ir-rigation programs for their Apple microcom-puters.

Agriculturists who rely on their own micro-computers will have fewer tools with agricul-tural applications immediately available. Tel-ephone couplers into the larger systems areprobably necessary to have adequate agricul-tural programs. Such linkages provide the bestof the small and large systems, but they are farfrom routine now. Microcomputers that aresufficient for agricultural applications cost$4,000 to $5,000 for the machinery, or hard-

.- —

Photo credit: USDA-Agricultural Research Service

Replacing the driver? Agricultural engineer RobertSchafer presents tomorrow’s farmers with the circuitboard from a computerized guidance system for tractors

and other farm machinery, Research shows thatcomputer-controlled traffic across croplands

can reduce soil compaction considerably

ware, and an additional $2,000 to $3,000 forprograms, or software. The more elaborate andexpensive microcomputers also are more flex-ible, They are faster and easier to use, and theirstandard features allow hardware and software“extras” to be exchanged among differentbrands,

The trend to greater reliance on computersin agriculture has begun despite the substan-tial costs involved, A number of vital institu-tional issues remain to be resolved, including:1) the role of the Federal Government in tech-nology R&D, 2) the role of Federal and Stateagencies in training, and 3) the need for im-proved cooperation among various agencies.These issues may redefine the role of theCooperative Extension Service, alter the audi-ence which it serves, and determine how wide-ly Government-developed computer technol-ogy is distributed. For example, some expertsthink that some extension services lag behindvocational schools and even behind some highschools in providing computer training.

Will Western agriculture participate fully inthe computer “revolution?” The technology isavailable, but evidence suggests that Western

Ch. XI—Selected Technologies Affecting Water and Land Management ● 329—

farmers and ranchers have trailed Midwestern- of water use, But computers can also be useders in its adoption, perhaps by as much as 10 as irrelevant and expensive toys; such uses willyears (15). It is clear that some computer ap- not necessarily help solve difficult water prob-plications can contribute to greater efficiency lems.

CONCLUSIONS

Agricultural management technologies thataffect water supplies in the arid and semiaridregion represent a wide combination of indi-vidual practices, including animal and plantmanagement, irrigation water management,cultivation practices, and computer and infor-mation management. Each of these manage-ment technologies is used in recognition thatwater is part of the natural system in whichit is impossible to affect anyfecting another.

part without af-

Management technologies have high poten-tial for maximizing production from availablewater, plant, land, and animal resources in thearid and semiarid region. Their application andsignificance in the future will depend to a greatextent on research efforts by the scientific com-munity, on economic costs and benefits of ap-plication, on managerial abilities of producers,and on decisions by policy makers at the local,State, and Federal levels.

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