Variabilidade espacial de atributos do solo em áreas de floresta nativa e de pastagens na zona da mata pernambucana

Abstract

The soils present in their composition spatial variability in the values of the chemical and physical attributes, being important to know them for efficient handling. The geostatistical methods and techniques used in conjunction with descriptive statistic has been of great importance in soil science, enabling assessing the structuring and measurement of magnitude of spatial variability of values of the chemical and physical attributes of the soil, by means of adjustments of the semivariogram and the maps of kriging. This survey aimed to evaluate the spatial variability of values of chemical and physical attributes in Yellow Latosol under native forest and pastures Zone of the Forest Pernambucana, using geostatistical techniques in the analysis of the data. In each area, the mesh mounted regularly spaced in two dimensions of 70 m x 70 m, where 256 samples of deformed and undeformed soil were collected at the crossing between lines and columns of the mesh, at 64 points georeferenced with a distances between them of 10 m in depths of 0.10 cm and 10.20 cm, totaling 512 samples in both areas, for determining values of the following chemical attributes of soil: active acidity (pH in CaCl2), exchangeable acidity (Al3+), potential acidity (H+Al), phosphorus (P), potassium (K+ ), calcium (Ca2+), magnesium (Mg2+), sum of bases (SB), ability to exchange cations (T), base saturation (V), saturation aluminum (m) and soil organic matter (MOS) and the following physical soil attributes: composition of the granulometric fractions of the soil, soil density, microporosity, macroporosity, accumulated total porosity. The geostatistical analysis was used to verify and quantify the existence of the degree of spatial dependence of values of the chemical and physical attributes of the soil. It was concluded: the values of the chemical attributes P, Ca2+, Mg2+, SB, T, V, MOS and the physical attributes microporosity and total porosity present strong degree of spatial dependence, and moderate spatial dependence for the chemical attributes pH, K+ , H+Al, m and for the sand fractions, silt, clay and the density variables of the xvi soil and macroporosity with greater reach for the variables H+Al (48.50 m) and clay (38.30 m) and lower range for the soil organic matter (10.80 m), microporosity and soil density (12.80 m), in the native forest area. In the pasture area, the values of chemical attributes P, K+ , Al3+, H+Al, SB, T, V, m and the silt fraction and the variables microporosity, macroporosity and total porosity feature strong spatial variability and moderate for the values of the chemical attributes pH, Ca2+, Mg2+ , MOS and Al3+, and, for the sand, clay and soil density fractions, with greater spatial range for the variables m (37.90 m) and soil density (23.74 m) and less reach for T (10.20 m) and sand (10.13 m). In the native forest area, the values of the soil chemical attributes set to spherical (45.83%), exponential (37.50%) and gaussian (16.67%) and of the values physical attributes to spherical (71.43%), gaussian (14.17%), and linear (14.28%) models.in the pasture area, the values of the soil chemical attributes were adjusted to spherical models (50%), exponential (37.50%), gaussian (4.17%) and linear (8.32%) and the values of physical attributes to exponential (50%), spherical (35.71%) and gaussian (14.29%) models.