Impacts of tillage and no-till on production of maize and soybean on an eroded Illinois silt loam soil

In the United States, millions of hectares of highly erodible cropland have been in the Conservation Reserve Program (CRP) for the past 10 years. Any conversion of CRP land back to maize (Zea mays L.) and soybean (Glycine max L. Merr.) production could require the use of conservation tillage systems, such as NT and CP, to meet federal and state soil erosion control standards. Evaluations of yield response of these conservation tillage systems such as NT and CP, over time are needed to assess the return of this land to crop production. An eight-year study was conducted in southern Illinois on land similar to that being removed from CRP to evaluate the effects of conservation tillage systems on maize and soybean yields and for the maintenance and restoration of soil productivity of previously eroded soils. Soils had been in tall fescue (Festuca arundinacea L.) sod for more than 10 years prior to the study. In 1989, no-till (NT), chisel plow (CP), and moldboard plow (MP) treatments were replicated six times in a Latin Square Design on sloping, moderately well-drained, moderately eroded phase of a Grantsburg soil (Albic Luvisol) (fine-silty, mixed, mesic Typic Fragiudalf). Starting with maize, maize and soybean were grown in alternate years. Surface crop residue levels were higher with the NT system than with the CP and MP systems. Soil temperature at 20 cm was lower (1.1 degrees C) with NT than with the other systems in 1996. Plant-available water was slightly higher with NT and CP systems than with the MP system. In 1995, maize was taller with the NT system than with the MP and CP systems. The MP system plots had higher plant populations in 1995 and 1996, but crop yields were higher with the NT system than with the MP system. The four-year average maize yields were equal (9.81, 9.74, and 9.80 Mg ha-l) for NT, CP, and MP systems, respectively, as a result of a significantly higher yield with the MP system in the first year which offset the higher yields with the NT and the CP systems during the last two years. The four-year average soybean yield with NT (2.90 Mg ha(-1)) was 15% higher than with the MP (2.55 Mg ha(-1)) system. Crop yields for eight years (four years maize and four years soybean) appear to show improved long-term productivity of NT compared with that of MP and CP systems. (C) 1999 Elsevier Science B.V. All rights reserved.