The influence of nitrogen and water on pastures of green panic, lucerne, and glycine at Lawes, South-eastern Queensland

Abstract

The influence of nitrogen fertilizer and supplementary irrigation on pastures of green panic (Panicum maximum var. trichoglume K. Schum. Eyles), green panic plus Hunter River lucerne (Medicago sativa L.), and green panic plus Cooper glycine (Glycine javanica L.) was measured in an experiment at Lawes, south-eastern Queensland. The yield of green panic increased and the yield of the legumes decreased when nitrogen fertilizer was added at the rate of 50 or 200 lb an acre a year. Nitrogen fertilizer significantly increased the total dry matter and nitrogen yields from green panic and green panic plus glycine swards, but not from green panic plus lucerne swards. Lucerne was more productive than glycine. Inclusion of legumes in the sward increased the total yield of nitrogen. For plots without nitrogen fertilizer, lucerne increased the nitrogen yields by about 230 lb an acre a year, and glycine increased yields by about 60 lb an acre a year. Most of this extra nitrogen was harvested in the legume.