Calibración de sensores de humedad del suelo con validación de campo : Calibración de sensores de humedad del suelo “PT91” El Arenal

Abstract

This work focuses on the development of calibration curves for two soil moisture sensors, property of FONAG. The Campbell Scientific CS650 sensors that use the Topp et al., (1980) equation have been installed at the PT91 “El Arenal” station in two sites (one with biomantle and another without biomantle). The generation of calibration curves was based on the TDR method (Time Domain Reflectomatry), it was based on the saturation and drying of unaltered samples. The samples taken were unaltered. The sensors were inserted in the samples to read the dielectric permittivity and relate it to the volumetric water content determined in the laboratory. The calibration curves obtained were applied to a time series of volumetric moisture content and compared with the historical data recorded by the sensors. The graphs identify an underestimation of the water content by the standard equation. As validation of the results and characterization of the soil under study, tests of physical properties were carried out, in which it was found for both PT91-CB and PT91-SB respectively: dry apparent density of 1.44 g/cm3 and 1.47 g/cm3 , wet apparent density of 1.68 g/cm3 and 1.72 g/cm3 , specific gravity of 2.609 and 2.517, porosity of 45% and 42%, organic matter of 2.88% and 2.48%, pH of 6.62 and 6.22, sandy-silty texture and gravimetric moisture content of 17% at both point of analysis were found in both sampling point, this demonstrating the vulnerability of paramo soils to overgrazing by sheep.