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.

本研究旨在对3支电容式探针（capacitive probes）进行校准，以将其应用于巴西半干旱区种植3个棕榈饲用无性系的老成土（Udult）中，构建土壤水力特性函数，并开展土壤水分含量（θ）与土壤贮水量的时空分布分析。本研究于巴西伯南布哥州塞拉塔尔哈达（Serra Talhada）的试验田内实施。为此，本研究借助5种土壤水分条件下的土壤密度、重量含水率数据及相对频率，完成了3支电容式探针的校准工作。本研究采用瞬态剖面法（instantaneous profile method）测定了土壤水分运移过程与土壤水基质势（matrix potential）。随后，对土壤水分含量（θ）与土壤贮水量的时空变化特征进行了分析。电容式探针的相对频率测定值与土壤水分含量（θ）数据呈现出极强的相关性，决定系数R²>0.87。基于瞬态剖面法，可构建以土壤水分含量（θ）为变量的土壤导水率与土壤水总势函数，二者的决定系数均较高（R²>0.91）。不同棕榈饲用无性系间的土壤水分含量（θ）无显著差异。