Axle load and tillage effects on soil physical properties and soybean grain yield on a mollic ochraqualf in northwest Ohio

Soil compaction due to vehicular traffic causes severe yield reductions on poorly-drained heavy-textured soils in northwest Ohio. Therefore, effects of harvest traffic and tillage methods were studied on soybean [Glycine max (L.) Mere.] growth and yield and soil physical properties of a clayey soil during the 1996 growing season. Three axle load treatments were imposed with a single axle grain cart loaded with dry corn (Zea mays L.) grain to achieve a control (0 Mg), a half full cart (10 Mg) and a full cart (20 Mg). Three tillage methods imposed as sub-plot treatments, consisted of no-till, chisel plow, and moldboard plow. Temporal changes in soil water content, soil bulk density, aeration porosity, and oxygen diffusion rate were measured for axle load and tillage treatments during the growing season and related to soybean yield. There were significant temporal changes in soil bulk density. Throughout the growing season, the soil bulk density values ranged from 1.2-1.6 Mg/m(3) measured by the radiation method, and 1.6-1.75 Mg/m(3) by the clod method. Soybean grain yield for the control treatment was 2.5 Mg/ha and was significantly reduced by 9 and 19% for axle loads of 10 and 20 Mg, respectively. The highest yield of 2.5 Mg/ha was obtained for the no-till treatment, and chisel and moldboard plowing significantly reduced soybean grain yield by 9 and 14%, respectively. Soybean grain yield was significantly correlated with soil bulk density, aeration porosity, the interaction of oxygen diffusion rate (ODR) with aeration porosity and soil bulk density. (C) 1998 Elsevier Science B.V. All rights reserved.