Effects of Long Term No-Tillage and Reduced-Tillage on Nutrient Stratification.

A long-term study of various tillage regimes on loess-deposited soil in the Macon Ridge area of Louisiana resulted in significant interactions between tillage type and soil depth. Tillage treatments were surface tillage, reduced tillage, and no-tillage; Cover crop treatments were native volunteer, Austrian winter pea, hairy vetch and wheat; Nitrogen rates were 50 and 100 kg N ha^-1. Soil was sampled at 0-7.5, 7.5-15, 15-30.5, 30.5 and 46 cm depth. Parameters measured were soil pH, percent base saturation, phosphorus, potassium, calcium, magnesium, sulfur, copper and zinc. There was a significant two-way interaction between tillage treatment and soil depth for pH, P, K, Ca, Mg, and S, suggesting tillage treatments affected nutrient (and H) concentration by depth. Cotton yield was significantly affected by tillage treatment with no two and three way interactions, suggesting crop yield can be affected by nutrient stratification.