Soils of Northern Great Plains are relatively young (11000 to 14000 years old) and have some of the highest organic matter levels (4 to 7%) of all mineral soils in the United States (Overstreet and DeJong-Huges, 2009). However, continuous cropping, poor management practices and loss of topsoil have adversely affected the soil organic matter levels. Continue reading
Tunsisa Hurisso and Steve Culman, School of Environment and Natural Resources, Ohio State University
In short, the answer is usually both.
Soil organic matter is a mixture consisting of various compounds (e.g. simple sugars, cellulose, proteins, etc.) derived primarily from plants and microbes. It represents 1-6% by mass of agricultural soils, but plays a disproportionate role in soil function. Organic matter in soils acts like a sponge, holding nutrients (sequestration or stabilization) that become available to plants when organic matter is broken down (mineralization) by the collective action of the soil food web (mainly by bacteria and fungi). In addition to nutrients, organic matter also enhances the soil’s water holding capacity, making farmlands more resilient to periods of drought. In contrast, when organic matter is depleted due to repeated plowing and/or removal of crop residues from the field, the ability of a soil to hold water and nutrients will be greatly diminished. Therefore, growers should strive for both organic matter stabilization and mineralization processes to ensure short-term crop productivity and to build long-term soil resilience.
Extension educators, crop consultants, and farmers working to improve soil health now have practical in the office or in the field resources. The new Iowa Soil Health Management Manual, Field Guide and a Soil Health Assessment Card are available at no cost.
The Iowa Soil Health Management Manual, Iowa Soil Health Field Guide, and Iowa Soil Health Assessment Card were recently published to increase understanding of soil health concept and their awareness of best management practices to protect soil health. These three publications are a collaborative effort between Iowa State University Extension and Outreach and the Natural Resources Conservation Service (NRCS), and can now be ordered or downloaded for free at the Extension Store.