Integration of Cover Crops in Mid-South Corn Production Systems.

The use of cover crops during fallow periods has increased to counteract the depletion of soil quality brought about by intensive monoculture.  Cover crops have the potential to provide adequate levels of mineralizable nitrogen to the soil, which can lead to decreased dependence on inorganic fertilizer application. Cover crops have been successful in northern states; however, the climatic conditions and management practices in the Mid-South pose potential limitations to the adoption of cover crops. A trial was established during 2014-2015 in northeast Louisiana to analyze the effects that winter cover crops and nitrogen rates have on corn (Zea mays L.) yield, soil N, soil C and NO₃^-. A split-plot design consisting of eight cover crops and four nitrogen rates as sub-plots was used in the study. Cover crops served as main plots and included 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), radish+rye mix and a fallow treatment, which served as the control. Cover crops were planted in fall and chemically terminated in early spring. Cover crops and N rate significantly affected corn yield over both years. Lower yields were obtained during the second year regardless of cover crop suggesting weather conditions and previous field management significantly impacted yield. Total C and N and soil moisture differed significantly among cover crops (p=0.0003, p=0.0005, p=0.0003, respectively) and were higher after cover crop establishment. Residual NO₃^- was significantly lower in spring (p<0.001), with the rye+radish treatment having the greatest decrease (23.7 kg/ha) followed by vetch (17.13 kg/ha) and crimson clover (17.34 kg/ha). Cover crops established under Mid-South corn production systems show potential for not only increased corn productivity but also more efficient N management.