Soil Surveys & Land Use Planning

©Vivek Srivastava

Objectives Knowledge of purposes & uses for soil

surveys Identify tasks for soil survey & the reports

involved Methods of soil evaluation & interpretation Use of electronic databases

Introduction Soil survey – fact-finding mission, following

by a report on the findings Description of the characteristics of the soils

in a given area Classification of the soils Delineate boundaries of soils on a map Predictions of behaviors of the soils

Introduction Contain

Data for many users Farmers, forecasters agronomists: evaluate potential

production of the soil, management needs to maximize that potential

Planners, community officials, engineers, developers, home buyers: evaluate the site for building construction purposes, strengths, limitations

Conducting a Soil Survey Before any surveying begins, a plan is made

& information is collected Conferences Collect aerial photographs Satellite images Initial field reviews

Soil Survey Reports Contents of a Soil Survey

Conducting a Soil Survey Preparation of a legend

Initial field reviews conducted in soil pits in the most extensive landforms

Soil-mapping unit: area of soil that is delineated from adjacent areas on a map Differences may be:

Slope Erosion Soil profile

Soil Survey Reports Physical & chemical properties of the soils Soil & water features Chemical analysis Clay mineralogy Engineering index data Soil classification

Soil Survey Reports Natural fertility Soil depth Tendency to accumulate soluble salts Soil structure Soil engineering properties Climate Natural vegetation Adapted crops & their expected productivity

Soil Survey Reports Recreational development potential Wildlife habitat Building site development Sanitary facility needs Construction materials Water management Engineering index

Soil Survey Reports Value of Detailed Soil Survey Reports

Most soil properties recorded in a soil survey change very slowly

Typically semiperminent properties: Land relief (topography) Soil texture Organic matter content Geologic origin

Soil Survey Reports Reasons why a resurvey may be done:

Some information was not gathered in a previous survey

New management practices Changes in crops grown Yield prediction changes

http://soils.usda.gov

Land Evaluation Land-use planning done for: urban areas,

rural areas Major issues:

Quality of environment Environmental sustainability of ag production

systems Pollution of nitrate, phosphate, pesticides Erosion of land Declining soil fertility

Land Evaluation Problems caused by these issues may have

various/multiple facets Agronomic Economic Political Social

Land Evaluation LESA system – Land Evaluation and Site

Assessment Guide the conversion of farmland to urban uses Attempts to preserve the best farmland Three procedures:

Land capability classification Current category of land is documented Soil rated according to capability

Land Evaluation Land Capability Classification

Classification & sub classification for all soil-mapping units

Class I Soils Can be used continuously for intensive crop

production w/ good farming practices No restrictions

Class II Soils More limitations than Class I land for crop production 2-5% slope is main difference

Land Evaluation Class III Soils

Severe limitations Requires more special conservation practices than

Class II to keep it continually productive Can have shallow soil Slopes 6-10% Shallow water tables

Land Evaluation Class IV

Severe limitations for cropping use Greater intensity of conservation practices for

cultivated crops that Class III Recommend permanent crops (e.g. pastures) Slope 12-18%

Class V Boulders, wetness, problems impractical to correct Not necessarily erosion risk Can’t be cultivated Use for pasture, range, woodland, wildlife habitat

Land Evaluation Class VI

Slope 18-30% Same limitations as Class V soils, except more need

for sustainable management practices

Class VII Severe limitations Extreme care to protect the soil

Even using grazing, wildlife, timber

Slope >30%

Land Evaluation Class VIII

Very severe limitations Steep slopes, rock lands, swamps, etc.

Can only be used for wildlife, recreation, watersheds, aesthetic appreciation

Land capability subclasses – soil groups w/in the 8 classes that explain the reasons for limitations of intensive crop production e – erosion hazard w - wetness

Land Evaluation s – shallow, droughty, stony, permafrost c – climate too cold or dry

Land Evaluation Ratings for Soil Potential

Indicates the relative quality of a soil for a particular use compared with other soils in a given area

Developed for planning purposes Supplement land capability classes, woodland

suitability groups, range sites, soil limitation ratings

Data Interpretation for Soil Uses Can be rated to have slight, moderate, severe

limitations Severe

Soil will require major soil reclamation, special design, high costs, or intensive soil maintenance to use for the item listed

Very Severe Great difficulty in the soil’s use, high costs, or

both

Data Interpretation for Soil Uses Slight & Moderate

May indicate problems w/: Shallow Low permeability Strong acidity High salt concentration Various other problems