Soil Microbial Diversity and Corn Grain Yield As Affected By Cover Crop and Nitrogen Combinations.

Inconsistent corn (Zea mays L.) yields and increased weather volatility suggest improving fertility management strategies with greater emphasis towards resilient cropping systems may also improve nutrient efficiency. Living ground covers can provide opportunities to influence soil microbiota, but few data exist that identify microbial composition and corn yield response to current N management strategies with cover crops. A field study was initiated in 2014 to investigate the effects of cover crops and N management strategies on soil microbial community composition and corn yield following wheat (Triticum aestivum L.). The study was arranged in a split-plot randomized complete block design with four replications. Main plots consisted of cover crop treatments preceding corn and included daikon radish 28.0 kg ha^-1 (Raphanus sativus var. Buster), forage oats 11.2 kg ha^-1 (Avena sativa var. Magnum), or no cover. Sub-plot treatments consisted of 179 kg N ha^-1 applied across six different management strategies: urea pre-plant incorporated (PPI), poultry litter PPI plus sidedress N V10-12, starter N applied 5 cm beside and 5 cm below the furrow followed by sidedress at V4-6, V10-12, or 50/50 (split) V4-6 and V10-12, and a zero N control. Soil data collection included ribosomal 16S DNA, soil nutrient monitoring, and soil respiration. Plant data included corn vegetative height, NDVI, SPAD, R1 tissue sampling, and grain yield. Prior to winter, N uptake increased 62% in above- and below-ground radish covers relative to aboveground oat biomass while both radish and oat cover crop treatments reduced soil nitrate > 71%. A significant cover crop by N management interaction occurred on zero N subplots where oat and radish ground covers reduced corn yield 11 and 18%, respectively. Preliminary soil microbial DNA results will also be presented and discussed.