Mid-South Cover Crops Influences Soil Microbial Communities.

Planting cover crops during fallow periods has increased to counteract depletion of soil quality and contamination of water resources common in intensive production systems such as those in the Mid-South. Research has shown that changes in management practices can affect soil microbial activity and studying these changes can offer insight on the impact of cover crops on soil. To study the effects cover crops may have on soil microbial activity and community structure a field trial consisting of a split plot design with cover crops, namely, cereal rye (Secale cereal L.), forage radish (Raphanus sativus var. longipinnatus), berseem clover (Trifolium alexandrinum), crimson clover (Trifolium incarnatum L.), winter pea (Pisium sativum L.), hairy vetch (Vicia villosa Roth) as main plots and N rates (0, 210, 240 and 270 lbs/ac) as sub-plots was established at LSU Agcenter’s Macon Ridge Research Station in northeast Louisiana. Soil samples (0-6 cm) were collected prior to cover crop planting (October 2014) and after chemical burn-down (February 2015). Soil were sieved to 4.75 mm and stored at 4⁰ C for Ester-linked Fatty Acid Methyl Ester profiles or air dried for β-glucosidase and β-glucosaminidase assays. Significant increase in enzyme activity was observed between cover crops, suggesting that cover crop type does affect soil enzymatic activity. Leguminous cover crops, namely berseem clover, crimson clover, and winter pea, had significantly increased β-glucosidase activity in spring.  Total soil N and C content increased in spring indicating greater nutrient cycling by microorganisms.  Microbial community structure was also affected by cover crop, being more complex under radish. Under a fallow treatment where N was limiting, arbuscular mycorrhizal fungi dominated likely a result of their ability to be nutrient scavengers. Microbial activity, sensitive to changes in management practices, and nutrient cycling, benefited from the integration of cover crops in production systems in the Mid-South.