Soil Chemical Response to Long-Term Conservation Tillage in a Tropical and Temperate Soil.

Chemical properties from two long term tillage studies will be compared, one from Brazil and the other from northeast Nebraska.  The Brazilian experiment was established at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (EEA-UFRGS), in Eldorado do Sul (RS), Southern Brazil (30°51x S and 51°38xW) in 1985. The soil is a sandy clay loam (Paleudult). It compares no-till, reduced till, and conventional till over three cropping systems and two nitrogen levels. The Nebraska soil is a silty clay loam (Coleridge, Cumulic Haplustolls), and has been in a combination of no-till, disk, and plow since 1985 with two rotations and five nitrogen rates. Soil samples were taken at the Nebraska site in the spring of 2014 at 2.5 cm intervals to 0.10 m, and 5 cm intervals to 0.2 m in the no-till and in the plow and disk samples were taken from 0-0.1 and 0.1-0.2 m. They were analyzed for C, P, K, Zn, Fe, Mn, Cu, Mg, Na, B, CEC, and base saturation. The effects of these treatments will be compared to similar measurements at similar depths previously taken from the Brazilian soils.