LONG-TERM TILLAGE EFFECTS ON A MOLLIC OCHRAQUALF IN NORTH-WEST OHIO .3. SOIL NUTRIENT PROFILE

Soil chemical analyses were performed 12 years after initiating a tillage experiment on a poorly drained clay soil in north-west Ohio. There were four tillage treatments: (A) continuous no-till for 12 years; (B) no-till for 10 years followed by plow-till for 2 years; (C) plow-till for 10 years followed by no-till for 2 years; (D) continuous plow-till for 12 years. Tillage methods had significant effects on soil pH, cation exchange capacity, Bray-P, exchangeable Ca and K, and base saturation of Ca, Mg and K. Tillage effects on soil properties were significant for the top 0-30-cm layer. Two years of plow-till following 10 years of no-till resulted in about 5% reduction of soil organic matter in the 0-10-cm layer. In comparison, 2 years of no-till following 10 years of plow-till resulted in about 15% increase in organic matter content of the surface layer. No-till plots had high concentration of P in the surface layers - 460, 330, 252 and 190 ppm in Treatments A, B, C and D, respectively. Two years of plow-till following 10 years of no-till increased P content of 0-10-cm layer by 28%. In contrast 2 years of no-till following 10 years of plow-till increased P content of the surface layer by 33%. The surface layer of no-till plots had lower pH and exchangeable Ca, but higher concentration of P, exchangeable K and exchangeable Mg than plow-till treatments. In general, tillage treatments had lesser effects on chemical properties of this clay soil of high inherent fertility than drastic long-term effects usually reported for some coarse-textured soils of low fertility. © 1990.