Modificação do uso da terra e seus impactos sobre o fósforo e carbono orgânico do solo no semiárido de Pernambuco

Abstract

In the Pajeú sertão, a semiarid region of Pernambuco, the deforested areas of caatinga are intensively used for agricultural cultivation until they deplete soil nutrients such as phosphorus and carbon. until exhausted, and after intensive use of the soil, these areas are abandoned and/or used for grazing animals. Thus, this work aimed to evaluate the dynamics of phosphorus and soil organic carbon under different conditions of land use, in the semiarid region of Pernambuco. Samples were taken in layers of 0-5, 5-10, 10-15 and 15-20 cm of soil under different land use situations: degraded pasture, regenerating caatinga and preserved caatinga. To characterize the chemical attributes of the soils, pH in water (1:2.5), exchangeable cations (Ca2+, Mg2+, Na+ and K+ ) were analyzed, in addition to available phosphorus and organic carbon. The evaluations showed a decrease in the phosphorus content of the surface layer, which was due to the processes of soil degradation generating a lack of nutrients, and the phosphorus content is being made available in the soil as there is a decrease in the levels of Na+ , Mg2+, pH and CTC. Therefore, the degradation of the area and land use without proper management provided an increase in Ca2+ and Mg2+, interfering with the availability of organic carbon, with a high CTC in the three areas. The pH and sodium showed a negative correlation, thus showing an increase in organic carbon as the area is preserved and a decrease with degradation. So, we warn that inadequate soil management can contribute to the loss of important nutrients to the soil such as phosphorus making it unavailable to plants and organic carbon, so it is important to emphasize that many years are needed for the recovery of phosphorus and organic carbon contents, this highlights the importance of preserving native vegetation in the semiarid region of Pernambuco and other northeastern states that belong to the caatinga biome.