Improvement of carpet grass (Axonopus affinis Chase) pasture by fertilization and oversowing with the aid of selective herbicides

SummaryAn experiment was done to determine the effect of spring and autumn application of asulam and dalapon, nitrogen fertilizer and oversown white clover (Trifolium repens L.) on the productivity of subtropical pasture dominated by carpet grass (Axonopus affinis Chase). Assessments were made of pasture yield, botanical composition, weed invasion and recolonization by pasture species during the 12‐month period following herbicide application. Both herbicides decreased the yield of carpet grass and increased that of the more productive paspalum (Paspalum dilatatum Poir.) except after autumn application when the yield of paspalum was greatly reduced by dalapon. White clover became established only on plots treated with herbicide and only after autumn application. Clover yields were greatest on plots treated with dalapon. Asulam was considered to be the most suitable herbicide for altering the balance between carpet grass and paspalum because dalapon initially reduced paspalum yield after autumn application and delayed recovery of total pasture. In addition, dalapon permitted greater invasion by broadleaf weeds. This work showed that herbicides have a potential role for speeding up botanical changes in unproductive carpet grass pasture and further refinement of the technique might provide a useful tool for increasing pasture productivity.