Although organic matter usually represents just 3 percent to 6 percent of healthy soil, it can greatly affect field and crop productivity. Soil organic matter originates from decomposing plants and animals, and according to a Cornell University guide, it physically, biologically and chemically benefits the soil.
From a physical perspective, organic matter enables soils to hold water, makes clay soils less sticky and controls soil crusting, based on the Cornell University guide. Soil organic matter supports biological activity through supplying food for soil organisms and diversifying soil microbial populations. Chemically, organic matter can lead to maintaining a stable soil pH level and holding nutrients in the soil.
A University of Minnesota guide estimates that subtle organic matter changes can cause more substantial changes in nutrient holding capacity, but the effect depends on soil type. For example, loamy sand soils with organic matter that drops from 2 percent to 1.5 percent lose an estimated 14 percent of their nutrient holding capacity. Organic matter declining from 4 percent to 3.5 percent in silt loams may reduce nutrient holding capacity by 4 percent.
Soil organic matter is classified into three categories, reports Cornell University. First, it includes living microbial biomass, such as microorganisms that break down plant residue, and the plant residues themselves. Active soil organic matter, or detritus, constitutes the second type of soil organic matter. Adding either plant residues and living microbial biomass or active soil organic matter enriches the soil and adds fertility. When these constituents decompose, they release nutrients that plants can absorb and use.
Humus represents the third soil organic matter type. As stable soil organic matter, it less intensively contributes to soil fertility. However, it offers other soil health-related benefits, such as influencing soil structure, soil tilth and the cation exchange capacity.
Farmers can adopt several practices to add organic matter to their soils. The University of Minnesota guide suggests supplementing the soil with livestock manure, growing crops that add surface residues and minimizing intensive tillage. Adopting practices that encourage root growth also can add soil organic matter. On average, roots represent 25 percent of corn and soybean production’s total organic matter output. We at BigYield.us® recommend applying BigBioYieldTM, our blend of multiple beneficial bacteria, to facilitate root growth and consequently increase organic matter production.
As farmers adopt practices that build soil organic matter, they may gradually notice improvements. However, they could wait a decade at the minimum before total organic matter registers a marked change, according to the University of Minnesota.
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