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United States Department of Agriculture

Agricultural Research Service

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Location: Integrated Cropping Systems Research

2013 Annual Report

1a. Objectives (from AD-416):
Identify soil microbiological indicators and quantify benefits of soil microbiological processes associated with agricultural management practices. Specifically, within corn production systems, evaluate cover cropping for reducing P inputs by stimulation of soil microorganisms, particularly arbuscular mycorrhizal fungi.

1b. Approach (from AD-416):
Establish (or use existing) replicated plots with differing fall cover crop treatments within corn cropping systems at three locations (Brookings, Dakota Lakes, TBD) including a check. Through plant and soil analyses, determine effect of cover crop on biological measures and their link to the seasonal bioavailability of plant nutrients.

3. Progress Report:
Because global reserves of mineral phosphorus (P) deposits are dwindling while global demand is increasing, inorganic P fertilizer costs are increasing rapidly. Current practices for agricultural application of inorganic fertilizers leads to inefficient use of this valuable resource and degradation of water supplies that receive P exported from fields. Arbuscular mycorrhizal fungi (AMF) are obligate partners with most crops and aid plant uptake of P that would otherwise be unavailable to plants. AMF are impoverished in most agricultural soils. We are determining how cover cropping can increase the numbers and diversity of AMF in agricultural systems to provide plants with P, as well as protection from drought, pests, and pathogens. Our research has shown that cover crops, particularly mixes, can increase AMF numbers and diversity in soils. We are examining which cover crops are most effective at increasing AMF diversity and enhancing particularly plant beneficial AMF. Part of this work is developing more efficient ways of characterizing AMF using DNA analyses to enable widespread assessment of the effect of farming practices on indigenous AMF fungi. Decreasing the amount of applied inorganic P and increasing the relative amount of applied P which is taken up by crops or remains within the field will mitigate costs of purchasing inorganic P, treating nutrient-enriched waters, and making reparations for degraded resources that propagate to other users. This project is a component of an effort to identify and promote cropping practices that enhance the ability of soils to retain and recycle nutrients so that they are efficiently utilized in production agriculture.

4. Accomplishments

Last Modified: 10/18/2017
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