Variability in soil moisture and infiltration on two Riverina soils

Abstract

Studies of variability in soil moisture and of a method for determining infiltration were conducted on two irrigated soils in the Riverina region, a sandy loam of the red-brown earth group and a clay of the grey and brown soil group respectively. Coefficients of variation were high in all cases. It is concluded that the use of 16 replicates gives adequate precision in the estimate of infiltration (C.V. of 8 and 12 per cent, for the two soils studied). Similarly, the use of 16 gravimetric determinations, each bulked from four sites, would give a satisfactory estimate for soil moisture (C. V. of less than 10 per cent. for the two soils studied). This number of samples is not excessive from practical considerations. Sampling for soil-moisture increment, following the type of irrigation used on these soils, should be carried out to a depth of two feet, but the duplication of gravimetric determinations is not warranted by the small increase in precision obtained.