Distribuição espacial dos limites de tolerância de perda de solos para o estado da Paraíba utilizando SIG.

Abstract

Changes in the physical and chemical attributes and biological processes of the soil over a long period of time lead to loss of ecosystem function and agricultural productivity. This work aimed to estimate, classify and map the soil loss tolerance limits for the lands of the State of Paraíba based on the values of the diferent soil classes, with variation in thickness of horizons and textural relationship, using modeling of geoprocessing data and techniques. The estimate was based on the efective depth, texture and density of the soils described in the 64 proiles from the Exploratory and Soil Recognition Survey and the Agricultural Zoning of the State of Paraíba and calculated using the Smith and Stamey (1964) method and using QGIS© for mapping. Soil loss tolerance followed the order of Oxisols > Cambisols > Argisols > Luvisols > Planosols > Neosols > Vertisols due to the inluence of parameters such as efective soil depth and textural relationship between B and A horizons. Soil loss tolerance presented in the very high class an average of 20.08 t ha-1 yr-1 and are associated with Oxisols, Argisols, Cambisols, Planosols and Gleissoils. The upper class presented average losses of 10.56 t ha-1 yr-1 under Argisols. The tolerance limit for losses in the middle class was 6.59 t ha-1 yr-1 distributed under the Luvisols. The low class occurred in Luvisols, Planosols and Neosols distributed in 389 mapping units with an average limit of 3.90 t ha-1 yr-1; in the very low class it occurred under the Vertisols, Nátric Planosols and shallow Neosols with an average of 1.64 t ha-1 yr-1 of soil loss tolerance distributed in 362 mapping units.