PLANTING DATE AND RESIDUE RATE EFFECTS ON GROWTH, PARTITIONING, AND YIELD OF CORN

Corn (Zea mays L.) growth has been shown to be affected by planting da te and amount of residue on the soil surface. The objective of this st udy was to determine if the adverse effects of cool soil temperatures on early seedling growth often associated with surface residues can be overcome by planting at later dates. Corn was planted at several plan ting dates (late April through early June) into soil that had residue applied at rates of 0, 33, 66, and 100% of that produced by the previo us crop. In general, spring-applied residue rates had little effect on measured plant responses. Planting corn before or after the optimum d ate resulted in reduced leaf area index, leaf area duration, total dry matter production, and grain yield. Maximum yield was achieved by pla nting corn about 10 May (near Lincoln, NE), regardless of the amount o f residue applied in the spring. Yield declined with earlier or later planting dates: yield declined more rapidly when planting was delayed than when planting was advanced. Results indicate that, with spring re sidue application, planting date recommendations can be made independe nt of residue conditions.