Changes in some physical properties of the surface of an impoverished red-brown eath under pasture

Abstract

The effects of growing monospecific swards of two grasses and a clover for 3 years on some physical properties of a loamy fine sand have been examined. Increases in the stability of aggregates in water (aggregation (2 mm)) occurred mainly in the surface 2 in. They were greatest under Wimmera ryegrass and least under subterranean clover. Over the 3 year period aggregation (2 mm) in the 0-3 in. layer generally increased linearly with herbage yield. Infiltration capacity was related similarly to yield of herbage in preceding years. Mulching caused insignificant aggregation changes. With increasing stability, aggregates became less dense, fractured more readily, and wet more rapidly. Despite marked increases in aggregate stability the soil reached only an 'immature' stage of structure development.