FDR ECH2O sensor performance in Spodosols

Abstract

Frequency domain reflectometry (FDR) is widely used to measure the soil water contents. However, the soil composition effects on FDR calibration has to be quantified to reduce the need for further calibration. Our objectives were to (1) evaluate the accuracy of EC-5 for measuring soil water content in sandy soils and (2) develop soil-specific sensor calibration curve. Disturbed and undisturbed soil samples were collected in a Sopossol profile (07º 37’ 30’’ S, 34º 57’ 30’’ W) representative of region sugarcane grown, in northeast of Brazil. Regression statistics analysis showed good accuracy and RMSE = 0.01 m³ m^-3, while without specific calibration the RMSE = 0.06 m³ m^-3. The EC-5 sensor should be subjected to field-specific calibration in sandy soils due to the low field capacity and water content during the growing season.