Losses of dry matter and nitrogen from autumn-saved improved pastures during the winter at Samford, south-eastern Queensland

Abstract

Yields of a number of ungrazed pasture mixtures declined over winter. Losses of dry matter and nitrogen were greater in a wet winter than in a dry winter. Total dry matter losses averaged 400 lb an acre (5.5 lb an acre a day), and total nitrogen losses 10.8 lb an acre (0.15 lb an acre a day). Losses of dry matter and nitrogen from the legume component, with the exception of Lotononis bainesii Bak., were far greater than the losses from the grass component. Mixtures containing frost sensitive legumes, and grass fertilized with 200 lb nitrogen an acre, as-urea, lost more nitrogen than control treatments and grass fertilized 72 with 100 lb nitrogen an acre. Lotononis bainesii increased in yield of dry matter and nitrogen over winter in contrast to the other legumes (Phaseolus atropurpureus D.C., P. atropurpureus X, Indigofera spicata Forsk., and Glycine javanica L.), which lost 80 per cent of their pre-winter yield of nitrogen. The actual yields of L. bainesii were, however, very low. In the wet winter of 1962 dry matter and nitrogen losses from Digitaria didactyla Willd., the main weed component, were far greater than those from the planted grass Paspalum plicatulum Michx, cv. Hartley.