Corn Yields Following Different Crimson Clover Establishment Methods in North Carolina.

Legume cover crops are being reevaluated in modern North Carolina crop rotations as potential replacements for inorganic N in conventional systems and manure N in certified organic systems.  The objective of this study was to evaluate the yield response of corn (Zea mays L.) produced using crimson clover (Trifolium incarnatum L.) to supply N following soybean (Glycine max L. Merrill).  Both moderately well- and poorly-drained sites were used, following soybean of different maturity groups (3, 4, & 5), which allowed cover crop planting with a seed drill or aerially on dates prior to, within, and after the optimum mid-September/early October window.  Overseeding prior to soybean leaf drop resulted in greater legume biomass and N accumulation than did overseeding at last soybean cultivation (August).  For later season soybean (MG5), productivity was much lower when planting was delayed until after soybean harvest (October/November).  Corn grain yield responses to clover and to inorganic N will be discussed.  They did not always reflect legume N contribution, probably due to drought stress during the corn growing season and/or moisture depletion by the cover crop at the moderately well-drained site.