FDR ECH 2 O sensor performance in spodosols

Abstract

Frequency domain reflectometry (FDR) is widely used to measure soil water content. However, the effects of soil composition on FDR calibration have to be quantified to reduce the need for further calibration. Our objectives were to: (1) evaluate the accuracy of EC-5 for measuring water content in sandy soils, and (2) develop a soil-specific sensor calibration curve. Disturbed and undisturbed soil samples were collected in one Spodosol profile (07º 37’ 30” S, 34º 57’ 30” W) representative of the region where sugarcane is grown in northeastern Brazil. Regression analysis showed good accuracy and low error (RMSE = 0.01 m 3 m -3 ), while without specific calibration the error was higher (RMSE = 0.06 m 3 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.