Evaluation of Winter Cover Crops on Nutrient Cycling, Soil Quality and Yield for Production Systems in the Mid-South
The practice of planting cover crops during fallow periods has increased due to the benefits provided to the soil system including improved nutrient cycling, addition of organic matter and a more diverse soil fauna resulting in better crop yield and an overall improvement of soil health. Research has shown that microbial activity is sensitive to changes in management practices and is a good indicator of whether the changes are benefiting the production system. To study the effects of cover type on corn (Zea mays L.) harvest parameters and soil chemical and biological properties a field trial consisting of a split plot design was established at LSU Agcenter’s Macon Ridge Research Station in northeast Louisiana. Treatments consisted of 8 covers: fallow, 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.) and hairy vetch (Vicia villosa Roth) and 4 N rates (0, 235, 268 and 302 kg ha-1). Corn grain yield decreased by 20% after cover crop but responded to the addition of N both seasons. Cover crops had a positive effect on soil C:N over time, indicating active mineralization, and NO3- - N decreased almost three-fold between fall 2014 and spring 2015 (p<0.05). Cycling of C, N and S was also affected by cover crops; β-glucosidase and arylsulfatase activity were highest in spring 2015 (after cover crop termination) and averaged 73 and 32.9 mg p-nitrophenol kg-1 soil h-1, respectively. Microbial community structure shifted after cover crop with soil microbial communities under leguminous covers (hairy vetch, crimson clover, winter pea and berseem clover) separating from the brassica (forage radish) and grass (cereal rye) covers. Arbuscular Mycorrhiza Fungi (AMF) was higher (9.07 mol %) under the 0 N rate compared to the 263-302 kg ha 1 N rates (average 7.28 mol %) indicating the establishment of symbiotic relationship between plants and AMF as a response to nutrient deficient conditions. Cover crops established under Mid-South corn production systems show potential for improving the chemical and biological properties of soil.