Variabilidade espacial dos atributos físicos do solo e sua relação com a produtividade do sorgo

Abstract

Sorghum (Sorghum bicolor L. Moench) is an interesting alternative for growing in succession (second crop). It has characteristics similar to corn (Zea mays) and some productive advantages such as tolerance to water deficit, high temperatures, and medium tolerance to soil acidity. However, factors such as low fertility and compaction can significantly affect its productive potential. So, it is essential to know the physical characteristics of the soil and its spatial behavior to perform the proper management. Precision agriculture is the tool that allows to carry out the most complex study of an area through geostatistics. This work aimed to analyze the spatial variability of the physical attributes of the soil, density and total porosity, in order to establish a correlation with the productivity data of the sorghum crop. The sorghum productivity data were collected in the second harvest of 2018. The evaluations of the physical attributes to obtaining density and total porosity (micropores and macropores) were carried out by means of undeformed sampling. The analyzed depths were 0 - 0.2 m and 0.2 - 0.4 m, with the aid of a systematic sampling grid of 2 points per hectare, totaling 50 georeferenced points. The descriptive analysis of the data obtained showed average values of high soil density and total porosity below the ideal. Macroporosity and the silt fraction presented a high coefficient of variation. The correlation tests showed significance between most of the physical attributes analyzed and with the productivity of sorghum. The semivariograms were adjusted in the exponential, spherical and gaussian models, allowing the interpolation of the data to generate contour maps. Thus, it was possible to identify a problematic region, denser, where there were lower values of crop productivity, showing negative correlations between sorghum productivity and soil density and positive correlations with total porosity. Therefore, dense areas with a low percentage of pores reduce the expression of the productive potential of the sorghum crop.