INFLUENCE OF USE AND SLOPE POSITION IN THE SOIL FERTILITY OF HILLSIDE AREAS

Abstract

Soil fertility parameters (pH, Ca, Mg, organic matter, phosphorus, and potassium) were evaluated, with the objective of verifying the influence of use and topographic position in soil fertility, in the Vaca Brava watershed, State of Paraíba, Brazil. Soil samples were stratified in six uses (agriculture; grassland; grass forage; forest; Mimosa Caesalpiniifolia, Benth.; and brushwood) and three positions in the landscape (shoulder, backslope and footslope). The average values and descriptive analysis of soil fertility parameters were low for the three studied positions, characterizing a soil with low fertility levels. In general, pH (shoulder = 5.11, backslope = 5.25, and footslope = 5.4), Ca and Mg values were not statistically different, presenting values ranging from 1.92 cmolc kg-1 to 1.25 cmolc kg-1, for the shoulder; 1.8 cmolc kg-1 to 1.17 cmolc kg-1, for backslope; and 0.74 cmolc kg-1 to 1.67 cmolc kg-1, for footslope, respectively. The texture class influenced soil properties with stronger intensity than distinct soil uses. The position in the slope did not influence soil attributes directly. However, they were expressed as texture variations. The analysis of the proportion of samples, in the different levels of sufficiency of P and K, based on different land uses, texture classes, and positions in the slope, indicated a generalized deficiency of P, which was more intense than the K one.

KEY-WORDS:Texture class; chemical and morphological soil properties; slope areas.