TILLAGE AND RESIDUE MANAGEMENT INFLUENCE ON CORN GROWTH

The large proportion (nearly 90%) of soil covered by crop residue with no-tillage (NT0 ) systems often results in decreased soil warming, reduced germination, and reduced early plant growth in parts of the Midwest section of the USA. We hypothesize that removal of some of the residue from the seeding zone could potentially improve crop production with NT0. Thus, we evaluated the impact of residue removal from a 30-cm-wide zone directly over the row in a no-tillage system (NT30) compared to NT0 and conventional moldboard tillage (CN) on soil growing degree days (GDD), soil temperature, and corn (Zea mays L.) growth and yield. This investigation was conducted in 1987 and 1988 on a Piano silt loam soil (fine-loamy, mixed, mesic, Typic Hapludalfs). Maximum growth rate (MGR) and relative growth rate (RGR) were calculated from weekly measured dry matter and leaf area. Soil temperature at 0-50 cm deep was measured hourly. Soil GDD was calculated from average soil temperature measured at the soil surface and 5 cm deep. Maximum growth rate and RGR were not significantly different between NT30 and CN treatments in 1987. However, mean values of MGR and RGR were significantly greater for NT30 than for NT0 in 1987. This occurred because soil temperature values with NT30 were similar to those for CN and significantly greater than NT0. Maximum growth rate and RGR values with NT30 were significantly greater than for CN in 1988. This may have resulted from a lower dry matter and leaf area index (LAI) with CN in 1998. During 1987, NT30 compared to NT0 had significantly greater time to emergence, MGR, RGR, and soil temperature in the seed zone (0-5 cm) and in the plow zone (0-20 cm). In 1988, NT30 had greater MGR, RGR, and LAI compared to CN because of the conserved soil water in the top 0- to 15-cm layer during an excessively dry soil season. Based on this research, NT30 Will provide soil thermal and water conditions that are conducive to good plant growth and production while reducing the potential for soil erosion.