Corn Yields as Related to Legumes and Inorganic Nitrogen1

High corn (Zea maysL.) yields require heavy N applications. Sources of inorganic N fertilizer have become less dependable and prices more expensive. A 3‐year study was initiated to evaluate the use of winter legumes and inorganic N as sources of N for corn production under modern culture. The experiment included three whole‐plot clover treatments (arrowleaf, Trifolium vesiculosum Savi; crimson, Trifolium incarnatumL; and fallow) and five inorganic split‐plot treatments ranging from 0 to 180 kg/ha N. Significant whole‐plot × split‐plot interactions occurred in 1975 for both grain yield and dry stover. Corn following clover produced 318% more grain than corn following fallow in 1975. When no N was applied, corn yield on fallow averaged 25 q/ha and increased 272% and 364% when grown following arrowleaf and crimson, respectively. The 180 kg/ha N did not increase corn yields significantly when compared with 90 kg/ha N with or without clover. Differences in stover yields between the 90 and 180 kg/ha N were not significant in any of the whole‐plot treatments in any year. Crimson clover produced in a 2‐year average about 1600 kg/ha more dry‐weight forage than arrowleaf. Total forage N at time of turning averaged 163 and 131 kg/ha, respectively, for crimson and arrowleaf. Differences in forage yield and in N content of the clovers were attributed to differences in maturity at time of turning. Growing a winter legume to replace all or part of the N may become a viable alternative in double‐cropping systems for corn production and conserving soll in the southern U.S. and in developing countries.