The root growth of irrigated perennial pastures and its effect on soil structure.

A separate of coherent organic particles obtained from soil suspensions by flotation and filtration is termed macroorganic matter. Three-year-old irrigated perennial pastures were found to have added 10 tons per acre of oven-dry macroorganic matter to a sandy loam at Deniliquin. Over half of this material hail been added to the top three inches of the soil. For any one pasture, as the macroorganic matter content of the top three inches of soil increased, infiltration rate decreased. When comparison was made at common macroorganic matter and soil moisture contents, soils under co-dominant white clover-perennial grass pastures were found to have higher infiltration rates than soils under lucerne-dominant pastures. The variability of the quantities measured is described.