CORN PRODUCTION UNDER 3 DISK CHISEL DEPTHS

Although mulch-till represents 21% of the corn (Zea mays L.) acreage in the USA, limited research has addressed the question of optimum chisel depth. Farmer-operated studies were conducted in 1988 and 1989 in New York on excessively drained (loamy-skeletal, mixed, mesic Typic Dystrochrept), well-drained (fine-loamy, mixed, mesic Glossoboric Hapludalf), and moderately well-drained (coarse-loamy, mixed, mesic Typic Fragiochrept) soils to evaluate the effect of spring chisel depth treatments at 5, 9, and 13 in. on surface residue, plant population, volumetric water content, and grain yield of corn. The 5-in. compared to 9- and 13-in. treatments had higher average surface residue (55, 42, and 37%, respectively) in all site-year comparisons and lower average populations (25603, 27004, and 26882 plants/acre respectively) at all sites in the wet 1989 season. The 5-in. compared to 9- and 13-in. treatments had lower grain yield in 1988 at the excessively drained (80, 86, and 82 bu/acre, respectively) and well-drained sites (137, 142, and 144 bu/acre, respectively), presumably because of less soil water depletion during extended dry periods. The 5-in. compared to the 9- and 13-in. treatments had lower grain yield at the excessively drained (91, 97, and 96 bu/acre, respectively) and moderately well-drained (82, 89, and 88 bu/acre, respectively) sites in 1989 probably because of lower plant populations. In this study, an increase in spring disk chisel depth to 9 in. was beneficial with no further benefits obtained at deeper chisel depths.