LONG-TERM TILLAGE AND ROTATION EFFECTS ON PROPERTIES OF A CENTRAL OHIO SOIL

Sustainable use of soil resources can be assessed from management-indu ced changes in soil properties from long-term experiments. Such data a re scanty, especially with regard to changes in soil physical properti es. Therefore, soil physical and chemical analyses were performed 28 y r after initiating a crop rotation-tillage experiment on a well-draine d Wooster silt loam soil (fine-loamy, mixed, mesic Typic Fragiudalf) a t Wooster, OH. All combinations of three rotations (continuous corn [C C; Zea mays L.]; corn and soybean [Glycine mar (L.) Merr.] in a 2-yr r otation [CS]; and corn, oat [Avena sativa L.], and meadow in a 3-yr ro tation [COM]) and of three tillage treatments (no-tillage [NT]; chisel plow [CP]; and moldboard plow [MP]) were maintained on the same plots for the entire length of study. All crops were grown every year. Soil properties studied for the 0- to 15-cm layer were: structural stabili ty of aggregates, bulk density, total porosity, penetration resistance , organic C, pH, cation-exchange capacity (CEC), and exchangeable K, C a and Mg. Mean bulk densities measured prior to tillage treatments and planting were 1.18, 1.24, and 1.28 Mg m-3 for CC, CS, and COM rotatio ns, respectively. The lowest bulk density was observed for the CC-NT c ombination. Total aggregation in CS was 26.9% greater than CC and 111. 2% greater than COM. With tillage treatments, aggregation was in the o rder of NT>CP>MP. Rotation treatments had no effect on aggregate size. In accord with bulk density, the relative magnitude of organic C cont ent was 100, 85, and 63 for CC, CS, and COM rotations, respectively.