MANAGEMENT DISCRIMINANT PROPERTIES IN SEMIARID SOILS

The physical properties of coarse-textured soils in semiarid regions o ften deteriorate with use. We hypothesized that the changes in the phy sical properties of the soil were related to the cropping systems empl oyed. Surface samples of 52 Entic Haplustolls under three different us es (24 under continuous cultivation (C), 18 under rotation with grass leys (R), and 10 virgin soils (V)) were analyzed for clay, silt, organ ic matter and water content, bulk density, compaction and aggregate st ability. Data were analyzed statistically using principal components, canonical variables, and discriminant functions. A satisfactory segreg ation of the soils according to discriminant properties (coarse organi c matter, aggregate stability, and susceptibility to compaction) was o btained. The model developed satisfactorily classified the soils under different uses (100% R, 83% C and 88% V). Principal component analysi s also showed that bulk density, compaction, and wet aggregate stabili ty are related to organic matter content. We conclude that, in the stu died region, the lower the ratio of organic matter to clay + silt cont ent, the more severe the physical deterioration of the soils.