The effects of saline irrigation water and gypsum on perennial pasture grown on a sodic, clay soil at Kerang, Victoria

Abstract

During five consecutive irrigation seasons at Kerang, Victoria, saline effluents were used to irrigate perennial pasture grown on a heavy clay, sodic soil. The nominal effluent salinities were 6000; 4000; 2400; 1600; 800 and 100 mg l-1 total soluble salt (TSS). After five seasons there were no significant differences in pasture dry matter yields between the 100 and 800 or 1600 mg l-1 TSS effluent treatments. In the fifth season there was a significantly higher (5 per cent) dry matter yield in the 800 mg l-1 TSS treatment when compared with the 1600 mg I-1 TSS treatment. With effluents above 1600 mg l-1 TSS, the higher the salinity the lower the pasture dry matter yield. The reason for the effluent of 800 and 1600 mg l-1 TSS producing similar yields to the 100 mg I-1 TSS is probably explained by the effects of electrolytes on soil permeability. Dry matter response to gypsum was not significant in the fourth and fifth seasons. In the second and third seasons there were significant responses at 10 and 20 t ha-1 respectively. There were no significant interactions between saline irrigations and gypsum applications. Medicago sativa (lucerne) and Lolium perenne (perennial ryegrass) proved valuable species under saline and sodic conditions. The percentage of Agropyron elongaturn (tall wheat grass) increased with salinity whereas the clover content decreased.