Soil organic matter is a central component of soil quality. Composed of relatively stable, decomposed or humified material, soil organic matter enhances soil quality by improving
Not all plant and animal residues are equally effective in maintaining or improving soil organic matter content. Soil organisms readily decompose fresh manure and very young
Photo by Steve Diver.
The green manure Crimson Clover provides robust growth and high nitrogen fixation.
Contaminants include excessive levels of plant nutrients, introduced pathogenic organisms, heavy metals, and residues of prohibited substances.
and fresh plant materials. As they decompose these materials, they release plant-available nutrients into the soil. In contrast, fewer soil organisms are able to break down and mineralize woody or dry materials, such as corn stalks, wheat stubble, or woodchips. As a result, decomposition of these materials takes longer than it does for more succulent ones. In addition, soil organisms are not able to decompose some of this organic material, and they transform it into soil humus instead. Humus gives good quality soil a soft and somewhat greasy feel. It is also responsible for building soil aggregates and increasing the capacity of the soil to hold water and nutrients. Thus, if you add a combination of succulent and woody residues to a field, you will fulfill a key objective of sustainable organic soil management—supplying crops with necessary nutrients while building soil organic matter and enhancing soil microbial health.
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