ChileanJAR

This work was carried out taking into account new trends ofplot management according to specific-site characteristics. Its objectives were to analyse Bray-extractable P variability in a field experiment with a wheat crop under two tillage systems: reduced tillage and notillage, and also to compare them with a degraded pasture. 30 soil samples spaced 30 cm from each other were obtained from a transect for each treatment during the months of July, October and December. Bray P values showed high spatial variability with variation coefficients ranging from 12 to 26% whereas the degraded pasture presented temporal homogeneity, with non-significant differences related to sampling time (P < O.OS). For the second sampling date (October), extractable P values from the reduced tillage treatment showed significantly lower values (P < 0.05) and no-tillage treatments displayed a significant increase ( P < 0.05). Bray P and gravimetric moisture showed a positive (r = 0.53, n = 90) and significant (P < 0.01) correlation coefficient under no-tillage conditions.