Response to the HL - 69 soil resistive moisture sensor in different substrates

Abstract

The objective of this work was to evaluate the response of the soil moisture resistive sensor HL-69 to different substrates. The study was split into two experiments. These were conducted at the Hydraulics and Irrigation Laboratory of the Agricultural Engineering Department of the Federal University of Ceará. Forty polyethylene vases with a capacity of 1030 mL were used, arranged on a benchwork. The treatments corresponding to the substrates were T1 (soil + commercial substrate (1: 1)); T2 (soil + hydroretainer (2 g kg-1); T3 (soil) and T4 (commercial substrate), with ten replicates per treatment. The readings of the Hl-69 sensors were carried out simultaneously with the weighing of the vases on an analytical scale. According to the most promising response, the second experiment was started with the adoption of the T3 treatment. The readings carried out in this work followed two different methodologies: Firstly, readings of the saturation condition until low moisture (wet-dry) were obtained, and later they were obtained from the low moisture point to saturation (dry-wet). The Hl-69 sensor shows poor performance in determining the water content in the adopted substrates, showing better performance for the T3 treatment. The methodology that obtained the best adjustment of the data was the soil readings in the wetting process (dry-wet).