Field calibration of capacitive probes, physical-hydric propriety and variation of water storage in soil cultivated with cactus forage

The objective of this work was to carry out calibration of three capacitive probes, to use them in the definition of physical-hydric functions and in spatial and temporal analysis of the soil water content (θ) and water storage in an Udult soil cultivated with three palm forage clones, in Brazilian Semi-arid. The study was carried out in an experimental area located in Serra Talhada, State of Pernambuco. Therefore, calibration of the three capacitive probes was carried out using soil density and gravimetric moisture data and relative frequencies in five conditions of soil moisture. It was applied the instantaneous profile method for determination of water flow in the soil and matrix potential of the water in the soil. After that, the space-temporal variation of θ and water storage in the soil were analyzed. Measures of relative frequency of the capacitive probes showed high relationship with the θ data (R2 > 0.87). From the instantaneous profile method, it was possible to determine the functions of soil hydraulic conductivity and soil water total potential, both in terms of θ, with high coefficients of determination (R2 > 0.91). There were no significant differences of the θ between palm forage clones.