Natural Resources Conservation Service Soil Health 101 What is soil health and how do we measure it? Name: Tom Roth Title: Conservation Agronomist Location, Salina Kansas Email: thomas.roth@ks.usda.gov
What is soil health? Soil health is the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation.
What does this mean for you and I? For people active in production agriculture, it may mean highly productive land, sustaining or enhancing productivity, maximizing profits, or maintaining the soil resource for future generations.
What is soil? Soil - The layer(s) of generally loose mineral and/or organic material that are affected by physical, chemical, and/or biological processes at or near the planetary surface, and usually hold liquids, gases and biota and support plants. (Glossary of Soil Science Terms, Soil Science Society of America)
What soil does Regulating water - Soil helps control where rain, snowmelt, and irrigation water goes. Water and dissolved solutes flow over the land or into and through the soil. Sustaining plant and animal life - The diversity and productivity of living things depends on soil. Filtering potential pollutants - The minerals and microbes in soil are responsible for filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic materials, including industrial and municipal by-products and atmospheric deposits. Cycling nutrients - Carbon, nitrogen, phosphorus, and many other nutrients are stored, transformed, and cycled in the soil.
Man, despite his artistic pretensions, his sophistication, and his many accomplishments, owes his existence to a six inch layer of topsoil and the fact that it rains. Paul Harvey
Indicators and their relationship s to soil heath Indicator Physical: soil structure, depth of soil, infiltration and bulk density; water holding capacity Relationship to Soil Health Retention and transport of water and nutrients; habitat for microbes; estimate of crop productivity potential; compaction, plow pan, water movement; porosity; workability
Indicators and their relationship s to soil heath Soil depth Soil Structure
Indicators and their relationship s to soil heath Indicator Chemical: ph; electrical conductivity; extractable N-P-K Relationship to Soil Health Biological and chemical activity thresholds; plant and microbial activity thresholds; plant available nutrients and potential for N and P loss
Indicators and their relationship s to soil heath Indicator Biological: microbial biomass C and N; potentially mineralizable N; soil respiration Relationship to Soil Health Microbial catalytic potential and repository for C and N; soil productivity and N supplying potential; microbial activity measure
Six components of soil quality / soil health management: Choosing specific practices within each component depends on the situation since different types of soil respond differently to the same practice. Each combination of soil type and land use calls for a different set of practices to enhance soil quality.
Enhance organic matter Whether your soil is naturally high or low in organic matter, adding new organic matter every year is perhaps the most important way to improve and maintain soil quality.
Enhance organic matter
Practices that increase organic matter include Leaving crop residues in the field. Choosing crop rotations that include high residue plants. Using optimal nutrient and water management practices to grow healthy plants with large amounts of roots and residue. Growing cover crops. Applying manure. Using low or no tillage systems.
Equipment
High residue crops Corn (grain) Sorghum (grain) Small grain (winter or spring) Forages (grass or legume)
Enhance organic matter
Nutrient Management Realistic yield goals. Last five years minus the high and low. 4R Principles Right Source Right Time Right Place Right Amount
Lake Erie 2015
Avoid excessive tillage Reducing tillage minimizes the loss of organic matter and protects the soil surface with plant residue. Tillage can also break up soil structure, speed the decomposition and loss of organic matter, increase the threat of erosion, destroy the habitat of helpful organisms, and cause compaction.
Water erosion
Wind erosion
Manage pests and nutrients efficiently An important function of soil is to buffer and detoxify chemicals, but soil's capacity for detoxification is limited. Pesticides and chemical fertilizers have valuable benefits, but they also can harm non-target organisms and pollute water and air if they are mismanaged. Nutrients from organic sources also can pollute when misapplied or over-applied.
Manage pests and nutrients efficiently Efficient pest and nutrient management means testing and monitoring soil and pests; applying only the necessary chemicals, at the right time and place to get the job done. Take advantage of non-chemical approaches to pest and nutrient management such as crop rotations, cover crops, and manure management.
Integrated Pest Management What weeds are you targeting? Sept Nov (winter annuals) marestail, mustard species, cheat, downy brome Very early spring (April) kochia Mid-spring (May) common sunflower, giant ragweed, common lambsquarter May June (summer annuals) Palmer amaranth, waterhemp, velvetleaf, foxtails, large crabgrass, barnyard grass and shattercane
How can cover crops suppress weeds? Layer of living cover crops or residues will reduce sunlight reaching the soil surface; smother and outcompete weeds for light, water and nutrients. Change the moisture and temperature conditions at the soil surface layer during weed seed germination and emergence. Some cover crops release chemicals from roots or decaying residue, inhibiting weed seed germination. Need lots of cover crop biomass!!
Prevent soil compaction Compaction reduces the amount of air, water, and space available to roots and soil organisms. Compaction is caused by repeated traffic, heavy traffic, or traveling on wet soil. Deep compaction by heavy equipment is difficult or impossible to remedy, so prevention is essential
Prevent soil compaction
Keep the ground covered Bare soil is susceptible to wind and water erosion, and to drying and crusting. Ground cover protects soil, provides habitats for larger soil organisms, such as insects and earthworms, and can improve water availability. Ground can be covered by leaving crop residue on the surface or by planting cover crops. In addition to ground cover, living cover crops provide additional organic matter, and continuous cover and food for soil organisms.
Crop Yield vs. evapotranspiration (ET) relationship for crops of the central High Plains (Stone et al. 2006) Max. ET for Full-season Variety Threshold ET Slope of Yield vs. ET Slope of Long- Term Yield vs. ET* Corn 25 in 10.9 in 16.9 bu/a/in 13.3 bu/a/in Grain Sorghum 21 in 6.9 in 12.2 bu/ac/in 9.4 bu/a/in Sunflower 22 in 5.4 218 lb/a/in 150 lb/a/in Winter Wheat 24 in 10.0 6.0 bu/a/in 4.6 bu/a/in Soybean 24 in 7.8 4.6 bu/a/in 3.8 bu/a/in Long-term (multi-year) slope is less than full slope doe to yield reducing factors such as hail, freeze, insects, diseases, etc.
Take the E out of ET Crop residue that completely covers 70 to 75 percent of the soil surface reduces evaporation by 50 to 65 percent. (Klocke et al., 2009) Reduce evaporation in the growing crop 3.4 3.6 inches Reduce winter evaporation 2 inches Potential to save up to five inches of water per year
Water erosion
Wind erosion Rolla, KS 1935 Colby, KS May, 2004
Diversify cropping systems Diversity is beneficial for several reasons. Each plant contributes a unique root structure and type of residue to the soil A diversity of soil organisms can help control pest populations A diversity of cultural practices can reduce weed and disease pressures Diversity across the landscape can be increased by using buffer strips, small fields, or contour strip cropping.
Diversify cropping systems Diversity over time can be increased by using long crop rotations. Changing vegetation across the landscape or over time not only increases plant diversity, but also the types of insects, microorganisms, and wildlife that live on your farm.
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