Spatial variability of the physical quality of soil from management zones

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The uniform management of soil, without considering the local soil spatial variability of its properties, may accelerate its degradation process. The objectives of this study were to: (i) delineate homogeneous management zones (HMZs) using the multivariate analysis approach, and (ii) evaluate the effect of uniform soil management on the physical–hydraulic attributes of these HMZ. The study was carried out in two fields: field 1 (F1) of 312 ha and field 2 (F2) of 297 ha. After collection of soil samples (grid approach) and laboratory analyses, principal component and cluster analyses were applied to define the HMZ in each field. After a new visit to the fields to confirm the variation of HMZ, soil profile samples were collected for soil quality analysis. The HMZ corresponded to soil spatial variability at the mineralogy level. The HMZ were defined by the soil physical attributes bulk density (Bd) and structural porosity in fields where soil spatial variability had greater homogeneity (F1), and by chemical attributes when it was more complex (F2). Considering uniform management, in F1, a marked reduction in structural porosity was observed in 46% of the 312 ha. F2 had an accentuated reduction in structural porosity of 26% and an increase in Bd in the other 24% of the surface layer (0.00–0.30 m). These results confirm the hypothesis that uniform management can increase the soil degradation and potential erosion, and that dividing the field into HMZs can result in a more adequate and sustainable soil management.