SPATIAL VARIABILITY OF SOIL ATTRIBUTES IN AN UNDERGROUND DAM PLANTING AREA IN THE MIDDLE BACKLANDS OF ALAGOAS

Abstract

This study aimed to evaluate the spatial variability of soil chemical and physical attributes in an area under the influence of an underground dam (BS) located in the municipality of São José da Tapera, Médio Sertão de Alagoas Territory, Brazilian semiarid region, with an emphasis on identifying spatial patterns associated with land use and management. Soil samples were collected in the 0–0.20 m layer at 16 georeferenced points, covering cultivated and non-cultivated areas, for analysis of pH, available phosphorus (P), sum of bases (S value), organic carbon (CO), electrical conductivity (EC), aluminum saturation (PST) and particle size. The data were analyzed using a deterministic interpolator (Spline), which allowed observing the spatial distribution of the attributes. The results indicated that the highest soil fertility values ​​(S, P and CO values) were concentrated upstream of the underground dam wall, especially in points under intensive vegetable cultivation with organic fertilization. The granulometry revealed a random distribution, with a predominance of sand near the wall of the underground dam, due to the accumulation of coarser sediments in the riverbed. The underground dam did not demonstrate a direct influence on the variability of chemical attributes, except for its possible effect on the TSP, but it contributed indirectly to the improvement of soil quality through water and sediment retention. The results obtained reinforce the importance of using conservationist practices for soil and water management in areas of underground dams, aiming at promoting a more productive and sustainable environment. The interpolator demonstrated efficiency in identifying spatial patterns of distribution, providing technical support for the planning of appropriate soil management actions aimed at optimizing the use of the underground dam.