CORN YIELD AND WATER USE CHARACTERISTICS AS AFFECTED BY TILLAGE, PLANT DENSITY, AND IRRIGATION

ABSTRACT. Corn (Zea mays L.) was grown on a deep, well drained silt loam soil (Aridic Argiustolls) at Colby, Kansas, from 2004 to 2007 using three plant densities (66,300, 74,500, or 82,300 plants /ha) under conventional, strip, or no tillage systems for irrigation capacities that were limited to 25 mm every 4, 6, or 8 days. Corn yield increased approximately 10% (1.43Mg/ha) from the minimum to maximum irrigation capacity in these four years of varying precipitation and crop evapotranspiration. Although strip tillage and no tillage had numerically greater grain yields than conventional tillage in all four years [approx. 8.1 % and 6.4 % (1.11 and 0.88 Mg/ha), respectively, for the four‐year average], strip tillage was significantly greater in only two years and no tillage in only one year. Seasonal water use of the crop tended to be greater for the strip tillage and no tillage treatments as compared to conventional tillage and was significantly greater for strip tillage in two years and for no tillage in one year. The small increases in total seasonal water use (<10 mm) for strip tillage and no tillage correspond with greater grain yields for these tillage systems. Water productivity (grain yield/crop water use) also tended to be numerically greater (three of four years) for the strip tillage and no tillage treatments as compared to conventional tillage because of increased yields for the reduced tillage schemes. Increasing plant density from 66, 300 to 82,300 plants/ha generally increased grain yield and water productivity (four‐year average of approximately 6 % for each factor). Results suggest that strip tillage obtains the residue benefits of no tillage in reducing evaporation losses without the yield penalty that sometimes occurs with large amounts of residue. Both strip tillage and no tillage should be considered as improved alternatives to conventional tillage, particularly when irrigation capacity is limited