Selecting Optimum Planting Dates and Plant Populations for Dryland Corn in Kansas

Corn (Zea mays L.) production practices have to be evaluated periodically to ensure that producers are fully using improvements in hybrids. A 2-yr study was conducted to assess corn yield response to plant population, planting dates, and hybrid maturity. The study was conducted at three sites during the 1994 and 1996 growing seasons. A 102 and a 113 d relative maturity corn hybrid were established at plant populations of 14 000, 20 000, and 26 000 plants/acre. Planting dates in early April, May, and June were also used. At two locations, delaying planting from April to May decreased yields slightly. At the third location, yields increased 27 bu/acre as planting was delayed until early May. Delaying planting at this location resulted in ear development occurring after a period of severe drought, which reduced yields with the April planting. At all three locations, delaying planting until early June reduced yields as a result of ear development under higher temperatures and grain fill occurring under cooler temperatures. Increasing population from 14 000 to 20 000 plants/acre resulted in a yield increase of 14 bu/acre across all six environments. Grain yields increased an additional 4 bu/acre when plant population was increased to 26 000 plants/acre. When planted in April or May, the full season hybrid produced higher yields than the earlier maturing hybrid. Corn producers in north central and northeast Kansas can increase corn yields by using planting dates in April and a population of approximately 26 000 plants/acre.