Spatial and temporal distribution of the water content of a red-yellow argissol cultivated with beans (Phaseolus vulgaris L.) irrigated by center pivot.

This study aimed to identify and assess the spatial and temporal distribution of the water content in a red-yellow argissol cultived with bean, irrigated by central pivot. The samplings were made at a depth of 30 cm, in systematic grid of 10.0 by 10.0 m with 108 and 54 sampling points in conventional tillage (CT) and no tillage (NT), respectively, sampled at four stages of crop development: V3 (1st trifoliated leaf), R6 (flowering), R8 (filling of string beans) and R9 (physiological maturity). The water content of the soil was determined by the greenhouse standard method and the analysis of spatial dependence was obtained with the GS+ Program. The semivariograms presented dependence spatial in conventional tillage, adjusting to the spherical model with ranges of 68.5, 78.3, 73.3 and 75.4 m, and in no-tillage system with ranges of 172.3, 210.9, 193.7 and 100.0 m for the steps V3, R6, R8 and R9, respectively. The relationship between the nugget effect and sill indicated that the spatial dependence was strong, lower than 25%. Using the graphical representation of the surface, the area studied presented higher water content at the low elevation and lower water content at the part of high elevation. Overall, the soil water content in CT showed a narrower range of spatial dependence on the scale, compared to soil water content in NT. The spatial distribution mapping of water content in the soil showed that there is a stability of the time variability for water content in the two cultivating systems.