A comparison of gypsum blocks and evaporimeters for irrigation control

Abstract

Gypsum blocks were used to schedule plot watering in a flood irrigation trial, conducted with perennial pasture on a red-brown earth. Pre-irrigation soil water storage to a depth of two feet (S inches) was related by regression methods to the average moisture bridge readings (M logohms) for gypsum blocks installed in the topsoil, and to accumulated losses (( E-R ) inches) from an Australian tank evaporimeter, an American type A pan, and a Wright-Rain Irrigation Indicator. Taken over two or more seasons evaporimeter losses were as good a guide to soil water storage as were the gypsum block readings.