Determination of field capacity in Oxisols using the flux density method, Arya-Paris model, and pressure chamber

ABSTRACT The field capacity of Oxisol was evaluated using the flux density in the field, Arya-Paris model, and Richards pressure chamber with non-deformed samples, and the water retention curve and soil moisture were determined using the Arya-Paris model at a pressure of 10 kPa. The research was conducted at the Federal University of Rondonópolis, Mato Grosso state, Brazil. The soil evaluated was Oxisol at depths of 0-10 and 10-20 cm. Using the flux density method, at a water flux density q = 0.10 mm per day and 1.0 mm per day, soil moisture values at field capacity were 0.30 and 0.32 m3 m-3, respectively, at a depth of 0-10 cm and 0.28 and 0.31 m3 m-3, respectively, at a depth of 10-20 cm. Comparing the results obtained with the pressure chamber with those of the field capacity obtained for q = 0.1 mm per day, the mean absolute error and bias were 0.880 and -0.218, respectively, for the 0-10 cm depth and 2.57 and -2.57, respectively, for the 10-20 cm depth. Field capacity of Oxisol can be obtained by subjecting undeformed 50 cm3 samples to a pressure of 10 kPa. The Arya-Paris model is an alternative for determining the soil water retention curve and the field capacity of Oxisol.