measuring soil health - assessment tools · 2017-01-17 · biological soil health indicators...

Measuring Soil Health -Assessment Tools

Jeff Hemenway NRCS – Soil Health Specialist

Soil Health Indicators

• Chemical • Physical • Biological

Chemical Physical

Biological

Presenter

Presentation Notes

Soils have chemical, biological, and physical properties that interact in a complex way to give a soil its quality or capacity to function. An indicator is an indirect measure of soil quality or soil function. They are not measures of soil quality, but collectively tell us whether the soil is functioning normally. Physical properties - infiltration, structure, aggregate stability, porosity, and bulk density. Chemical properties - salinity, soil pH, cation exchange capacity, plant nutrients, organic matter content, etc. Biological properties - earthworm numbers, and other animal activities that are important in soil development and fertility, soil respiration, pitfall trapping, microbial biomass, cotton strip assay, soil food web structure, etc. Organic Matter has physical, chemical, and biological properties. It is considered part of all three groups.

What are we talking about? • Nutrient Deficiency/loss

• Loss of Soil Organic matter • Loss of Biological diversity • Soil Compaction • Erosion • Soil Salinitization • Sodification • Others (etc.)

Chemical Soil Health Indicators

• Nutrient Supply (N, P, K) micros– (Conv. Lab Analysis)

• Potentially Mineralizable Nitrogen – (Haney)?

• Soil pH • CEC • Salinity and Sodicity

– EC- Sat. Paste vs 1:1 – SAR

4

Presenter

Presentation Notes

List of chemical indicators that will be covered in more detail in this section. Organized by general category: Optimize pH, nutrients Maximize CEC (OM) Minimize CaCO3, Na, contaminants

5

Physical Soil Health Indicators • Soil Structure (granular, subangular, platy) • Soil Pores/Macropores • Aggregate Stability (Wet, Jornada) • Bulk Density/Compaction • Infiltration (single ring) • Surface residue/litter • Surface Crusting • Available Water Holding Capacity

Presenter

Presentation Notes

List of most commonly used physical soil quality indicators. Each will be covered in detail the slides to follow. All of these indicators are interrelated. What affects one, or by changing one, could affect one or more of the others. As individual indicators are discussed you will see this interaction. Last 4 specific to water movement. All important for root growth, aeration, erosion protection.

Biological Soil Health Indicators

– Microbial Biomass (PLFA) – Soil Respiration (Solvita) – Potentially Mineralizable Nitrogen –

(Haney)? – Plant Roots (number/mass) – Other Indicators (Arthropods, earthworm) – Others

Presenter

Presentation Notes

Microbial biomass (bacteria and fungi) is a measure of the mass of the living component of soil organic matter. The microbial biomass decompose plant and animal residues and soil organic matter to release carbon dioxide and plant available nutrients. Farming systems that return plant residues (e.g. no-tillage) tend to increase the microbial biomass. The microbial biomass consists mostly of bacteria and fungi, which decompose crop residues and organic matter in soil. Soil respiration refers to the production of carbon dioxide carbon when soil organisms respire. This includes respiration of plant roots and microbes. The importance of soil biology has long been recognized. Biological systems are highly sensitive and a change in the biological status of the soil may provide us with an early warning of potential environmental damage. The balance of the entire community perform many functions that affect agroecosystem health. But this web of complex interactions is very difficult to measure directly. Recently sophisticated methods of assessment been developed. However, in many cases their interpretation remains problematic. Other indicators: Cotton strip assay – index of decomposition in soils - decomposition rates were measured using a standard method known as cotton strip assay. This method measures the potential of cellulose decay within the sediment and water column. Arthropod Pitfall trapping - To catch animals that crawl through the leaf litter. These traps are usually left for several days allowing for the capture of nocturnal animals. (biodiversity) Microbial quotient--microbial biomass divided by the soil respiration rate

Soil Degradation Spiral Poor Land Management

Aggregation Degradation

Compaction & crusting

Water & Wind Erosion Plant Growth

Yield

Reduced Soil Productivity

Soil Biology

30003500400045005000550060006500700075008000

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

Year

So

il C

(g

m-2

)

Conventional Tillage

Reduced Tillage

53% of 1907

61% of 1907

SOIL C LOSS/ORGANIC MATTER LOSS

-100 -80 -60 -40 -20 0 20 40

Soil

Carb

on C

onte

nt

Years Before Present | Years After

Management Changes(HIGH)

(LOW)

Native Prairie Row Crop Agriculture

Intensive Tillage ?

CRP Grass ?No Tillage ?Cover Crops ?

Stover Removal ? Sustainable Production?

FarmerDecisions

https://prod.nrcs.usda.gov/Internet/FSE_MEDIA/stelprdb1252069.jpg

South Dakota Acres Under No-Till Farming on All Planted Cropland

Tillage is Destructive to soils What things change when you stop tilling the soil?

• Soil pores remain continuous • Soil aggregates form and are not destroyed • Soil Food Web increases and diversifies • Weed seeds are not planted • Water is captured (infiltration) and stored

(AWC) • Bulk density increases slightly; then stabilizes • Soil fungi and earthworms increase • Microarthropods increase

Presenter

Presentation Notes

Here are 8 positive changes in the soil that occur when you stop tillage. Pores remain continuous-allows for increased infiltration Aggregates form – increase soil stability, improves aeration and provides habitat for soil microbes SFW – adds trophic levels and complexity, increasing functional groups Water is held in place by increased SOM and held until plants require it Bulk density decrease over time to levels that approach native condtions Soil organisms flourish because there habitat is not being destroyed

Dynamic Soil Properties -2008

• Study was initiated in 2008 to look at – Effect of management/invasive species on soils – Further define causes of transitions between states

• What are the dynamic soil properties – Color/organic matter – Soil aggregate stability – Bulk density/porosity – Microflora and microfauna – Carbon:Nitrogen ratio – Infiltration

Dynamic Soil Properties Study Sites

DSP Study sites

2008 &2013 2012 &2013

2012

2014

2009

2009

2008

2016

2015

2015

Dynamic Soil Properties

Barnes – Loamy ecological site 2008 Study site Duel County, SD

Dynamic Soil Properties study site

Similar to Rapid Carbon Assessment protocol Paired sites are located on same soil, but widely different management

Presenter

Presentation Notes

This shows the typical layout of a paired study site.

Study Site 1 – Bruce, Steve and Lance collect soil samples on the native state. The soil series is Barnes.

Invaded State

89% Introduced species (5 species)

11% Native grasses and forbs (6 species)

(by weight)

Native / Invaded State

88% Native grasses, forbs & shrubs (19 species)

12% Introduced species (3 species)

(by weight)

Barnes soil

Infiltration

0

5

10

15

20

25

Rotation Continuous

5

0.55

Inches/hr

Bulk Density

0

0.2

0.4

0.6

0.8

1

1.2

1.4

BulkDensity (g/cm3)

0-3" 3-6"

Horizon

Native

Invaded

Soil Aggregate Stability

0.00.51.01.52.02.53.03.54.04.55.05.56.0

Stability Rating

Surface 0-3" 3-8" 8-12"

Horizon

NativeInvaded

Infiltration – There were dramatic differences between the two states in infiltration rates. On the invaded grass state, the second inch of water took more than 5 times longer to enter the soil. After the initial wetting, the infiltration rate was approximately 2.17 inches/hour for the native state, and 0.55 inches/hour for the invaded.

1.2

21.027.6

109.2

0.0

20.0

40.0

60.0

80.0

100.0

120.0

Native Invaded

Elap

sed

Tim

e (m

in.)

1st Inch2nd Inch

Carbon/Nitrogen Ratio

• No appreciable difference • Organic matter

– Total amount not greatly different – Distribution significantly different – better

distribution of organic matter in the soil profile under rotationally grazed

Glomalin

• An indicator of arbuscular mycorrhizal fungi activity.

• Native grass site had 20% more glomalin in the soil profile compared to the invaded grass site. – Is this enough of a difference to be considered a

trigger for the effect on infiltration? – Would the change in glomalin be sensitive enough

to use as an early warning sign?

Dynamic Soil Properties - Sampling Protocol Notes: Proposal Rapid carbon protocol plus Soil Sampling Standard Cluster sampling – i.e. central pedon plus four cardinal satellites - 30 meters from center 5 cm - surface subsample BD sampling all horizons Complete morphological soils description – (i.e. – 232) Single ring infiltration – central pedon plus all satellites Total carbon Inorganic carbon -Active carbon, POM, permanganate test?, humic acids? - Note: May need to do carbon on all horizons ; not just A horizons. Ec pH Soil Aggregate stability – A horizon(s) Central pedon – sampled for soils characterization Plant Sampling NRI procedure – 5 plot total harvest Point Intercept procedure Duff layer collection – measure thickness?

•2012 Study Site Mellette County, SD

Dynamic Soil Properties- (i.e. Soil Change with Management) 2012 Study Site Mellette County, SD

Mellette County Kube soil

Rotational Grazing Hayland

Mellette County Kube soil

Hayland Rotational Grazing

Kube Soil – Native Range site

Infiltration Rates

SD002-1 30 sec.

SD002-2 2 min.25 sec.

SD002-3 34 sec.

SD002-4 50 sec.

SD002-5 6 min. 47 sec.

Average - 2 min. 13 sec.

Kube Soil – Cropland si

Infiltration Rates

SD001-1 3hr. 57 min.

SD001-2 34 min.

SD001-3 37 min.

SD001-4 52 min.

SD001-5 2 hr. 29 min.

Average - 1hr. 41 min.

• 2014 Study Site Walworth County, SD

Native Range

Cropland/New range seeding

Cropland/New range seeding Grass/Alfalfa prior to 2011, No-till Oats/peas 2012, Sorghum/sudan in 2013, Range seeding in 2014: Big Bluestem, Side Oats grama, Green Needlegrass. Indiangrass, Switchgrass, Little Bluestem, forbs

Native Range Dominant and subdominant species (in order of dominance) are: Smooth bromegrass, Kentucky bluegrass, western wheatgrass, needleandthread, crested wheatgrass, and western snowberry.

Mobridge Cropland – Range Seeding

Mobridge Native Rangeland

Infiltration Rate -2nd Inch 005A 17 min. 6 seconds 005B 22 min. 30 seconds 005C 1 min. 30 seconds 005D 6 min. 18 seconds 005E 14 min. 30 seconds Ave. 12 min. 23 seconds

Infiltration Rate -2nd Inch 006A 48 minutes 006B 3 hrs 35 minutes 006C 4 hrs 50 minutes 006D 16 minutes 006E 26 minutes Ave. 1 hr 59 minutes

What we “know” so far • Management actions can be taken to degrade

or improve soil health – more emphasis needs to be placed on this.

• Management of cropland and grassland has a potentially large effect on infiltration/runoff.

• We need to sample-N,P,K micros S, Zn,Cl • A number of soil parameters are showing more

promise – C, OM, Structure, WAS, BD, EC, Infiltration.

Soil Health in South Dakota Predicting Infiltration Rates

Predicting Infiltration rates for Grazing lands and Cropland

• Based on plant community and management for both systems

• Grazing land • ESD Plant community and grazing management

• Cropland • Crop rotation and tillage system

RAINFALL INFILTRATION KIT

Grazing land ESD Plant Community – Management Scale

Both the plant community and the type of management are rated on a five-tier scale. Plant community (comparisons are to the respective ecological site description): 1 – Native plant community 2 – Plant community dominated by native plants 3 – Non-native cool-season grasses and/or short warm-season grasses have increased to the point of being co-dominant with native species which are normally considered dominant in the reference plant community. 4 – Non-native cool-season grasses and/or short warm-season have increased to the point of being dominant. 5 – Non-native cool-season grasses and/or short warm-season grasses have increased to the point of being completely dominant. If present, native species are difficult to find.

Grazing land ESD Management: 1 – Prescribed grazing is applied according to the Prescribed Grazing Conservation Practice Standard (528). 2 – Most aspects of the Prescribed Grazing Conservation Practice Standard (528) are applied, but not consistently. 3 – Typically this includes grazing at moderate stocking rates, but grazing periods cover most of a season (seasonal) or nearly for the entire season (season-long 4 – This typically includes moderate to heavy stocking rates that are applied season-long. Livestock often occupy the area for most of the growing season. 5 – This typically includes very heavy stocking rates for extended periods, often for the entire growing/grazing season. To determine the plant community/management scale rating, rate each using the scales above, then multiply the two numbers together. The overall rating will range from 1 to 25.

34 locations, 7 MLRAs, 8 ecological sites

Presenter

Presentation Notes

At 34 locations in 2013, the correlation between the predicted infiltration (predicted from the plant community composition and the management) and the actual was high. These data points were collected by two of the MLRA Offices in South Dakota.

Cropland Crop Rotation and Plant Diversity Management Scale Both the rotation and the tillage system are rated on a five-tier scale. Rotational System 1– Diverse cropping system that includes all four crop types. Perennials as well as cover crops are part of the system. Contains at least two thirds high residue crops – manure or grazing is part of the management system. 2 – Cropping system that includes all four crop types incorporated into the crop sequence. Contains at least two thirds high residue crops. 3 – Cropping system that includes at least 3 crop types in the cropping sequence. Contains 50-60% high residue crops with cover crops are part of the rotational system. 4 – Cropping system includes 2 crop types with 50% high residue crops or high residue mono-cropping systems. 5 – Mono-cropping system with a low residue crop

Cropland Tillage System: 1) No-till/strip-till - The soil is left undisturbed from harvest to planting except for strips up to 1/3 of the row width (strips may involve only residue disturbance or may include soil disturbance). 2) Ridge-till - The soil is left undisturbed from harvest to planting except for strips up to 1/3 of the row width. Planting is completed on the ridge and usually involves the removal of the top of the ridge. Planting is completed with sweeps, disk openers, coulters, or row cleaners. Residue is left on the surface between ridges. 3) Mulch-till – Full-width tillage that involves one or more tillage trips, disturbs the entire soil surface and is done prior to and/or during planting. Tillage tools such as chisels, field cultivators, disks, sweeps or blades are used. 4) Reduced-till (15-30% residue) - Full-width tillage that involves one or more tillage trips, disturbs the entire soil surface and is performed prior to and/or during planting. There is 15-30 percent residue cover after planting or 500 to 1,000 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. 5) Conventional-till or intensive-till - Full-width tillage that involves one or more tillage trips and disturbs the entire soil surface and is performed prior to and/or during planting. There is less than 15 percent residue cover after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Generally involves plowing or intensive (numerous) tillage trips.

Actual Values 2nd Inch

Actual Values 1st Inch

measuring soil health - assessment tools · 2017-01-17 · biological soil health indicators...

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