MAPEAMENTO DE ATRIBUTOS FÍSICO-HÍDRICOS EM LATOSSOLO VERMELHO SOB CANA-DE-AÇÚCAR EM CERES (GO)

Abstract

The mapping of soil physical and water characteristics can contribute to precision irrigation in sugarcane cultivation in the São Patrício valley region, Ceres Municipality, Goiás State (GO) Brazil. This paper aimed to determine and spatialize physical-hydric attributes in the sugarcane area at the Sugarcane Research Unit in Ceres (GO). The experiment comprised an area of 285 x 60 m with a 15 m sampling grid, in which a deformed and undisturbed soil sampling was carried out from January 2020 to January 2021. The evaluated attributes were: (a) clay (ARG); (b) sand (ARE); (c) silt (SiL); (d) soil density (Ds); (e) particle density (Dp); (f) total porosity (Pt); (g) macroporosity (macro); (h) microporosity (micro); (i) water retention in field capacity (FC); (j) water retention in the permanent wilting point (PWP); and (k) total water availability (TWA). Descriptive statistics were applied (mean, standard deviation, variance, mode, median, maximum, minimum, kurtosis, and normality) in addition to the Pearson correlation. The data were adjusted to theoretical models to obtain the semivariograms, selecting the best model, and the cross-validation technique was applied. Variables with spatial variability were interpolated by ordinary kriging and then iso-occurrence maps were made. The exploratory analysis showed that clay ranged from 367.1 to 578.3 g kg-1 with an average of 490.2 g kg-1 , and the soil was classified as clayey. TWA ranged from 0.15 to 1.14 with a mean of 0.53 mm cm-1 . Macroporosity showed high coefficients of variation (%CV), while Dp, sand, FC, Ds, and microporosity were low. All physical attributes showed moderate to strong spatial dependence viii with adjustments to Gaussian models predominantly for granulometry and exponential, and spherical for the others, ranging from 15.4 to 191.9 m. Dp showed little difference in depths on maps. The Ds, SiL, micro, and Pt attributes showed greater homogeneity in the area. Geostatistics is an appropriate technique in the interpolation and mapping of physical-water characteristics, also assisting in the area soil sampling in future studies. Results of TWA spatial variability allow defining two management units and show that the soil under study has low water retention in the available water range. This study provides information that enables decision-making in irrigation management and soil decompaction.