Soil spatial variability of phosphorus, potassium, and organic matter was studied in different soils and management systems, in two counties: a) Eldorado do Sul, State of Rio Grande do Sul, Brazil, on a Dark Red Podzolic-Kandiudult (conventional tillage, no-tillage, minimum tillage, and pasture), using a grid sampling of 1 x 1 m and at depths of 0-0.05 and 0.05-0.20 m; b) Passo Fundo, State of Rio Grande do Sul, Brazil, on a Dusky Red Latosol - Hapludox (conventional tillage and no-tillage) and on a Dark Red Latosol-Hapludox (pasture), using a grid sampling of 10 x 10 m and at depths of 0-0.10, 0.10-0.20, and 0.20-0.30 m. Wheat yield variability was studied only in Passo Fundo by harvesting areas of 1 m². The highest variability was found for phosphorus and potassium, with values approaching a lognormal distribution. Spatial correlation was found, in most of the cases, for soil properties of at the management systems studied, as well as for wheat yield. No-tillage exhibited greater coefficients of variation and lower spatial dependence ranges and, therefore, was assumed to be responsible for greater variability of these soil properties than the other systems. The least soil variability occurred with pasture. No-tillage also exhibited positive cross-correlation for wheat yield with phosphorus, with potassium, and with organic matter.
sampling; geostatistics; conventional tillage; no-tillage; minimum tillage; pasture