TILLAGE EFFECTS ON GROWTH AND YIELDS OF CORN ON GRANTSBURG SOIL

A project to determine village effects on soil properties and the growth and yield of corn was initiated in the spring, 1989 in southern Illinois on a sloping Grantsburg (fine-silty, mixed, mesic Typic Fragiudalf) soil previously in tall fescue [Festuca arundinacea (L.) Schreb] sod. Each tillage treatment [no-tillage (NT); chisel plowing (CP); and moldboard plowing (MP)] was replicated 8 times on 9 x 12 m plots. Corn (Zea mays L.) (in the first and 3rd years) and soybean [Glycine max (L.) Merr.] (in the second year) were grown in a rotation system on the plot area. This paper discusses the data collected during the two years of corn. Corn plant population was less for NT than MP in 1989, while in 1991 the plant population for NT was greater than that of CP. Corn grain yield in 1989 was least for NT and greatest for MP (8400, 9300 and 10, 500 kg/ha, respectively, for NT, CP, and MP). In 1991, tillage did not significantly affect grain yield. The grain yields for 1991 were 2,300 to 4,400 kg/ha lower than for 1989 due primarily to limited and poorly distributed rainfall and insufficient plant-available soil water in the 1991 growing season. Differences in grain yield in 1989 were attributed to effects of reduced plant population for AT into sod resulting possibly from effects of insufficient soil-seed contact which might have led to dehydration of seeds and subsequent failure to germinate. Another factor that might have affected germination was lower soil surface temperature for NT at planting as a result of residue on surface. Early in the growing season, NT system bad greater bulk density and greater resistance to penetration (soil strength) than the CP and MP systems. Greater regrowth of weeds at midseason in NT system appears to have had limited effect on plant available soil water since NT still bad greater values at tasselling and grain-fill. Most corn tissue nutrient content (by treatment) were in the normal range and appeared to have little association with 1989 yields. The significant first year plant population and corn yield advantages that the MP system bad over the NT system were masked in 1991 by the effects of rainfall. No-tillage planting into soybean residue in 1991 was much more successful than planting into a sod in 1989. Any conversion of conservation reserve land from sod into NT corn and soybean production could experience similar management problems and corn yield reductions the first year. The NT planting in soybean residue the third year made it easier to obtain sufficient soil-seed contact, provided a better rooting zone, bad better weed control and resulted in greater plant populations, Results suggest that the MP system productivity may be less sustainable over time than the NT system.