The effects of single compared with split applications of fertilizer nitrogen on the yield and seasonal production of a pure grass sward

Abstract

SUMMARYIn a 2-year experiment conducted on a pure S. 24 perennial ryegrass sward, fertilizer nitrogen in the form of ‘Nitram’ (34·5%) N was applied at rates of 100, 200 and 300 lb/ acre either as single dressings in the spring or as two, three, four or five split dressings at successively later dates in the growing season. Total yields of herbage dry matter and of crude protein, and their distribution over the season, were determined by cutting the herbage five times at intervals of approximately 5 weeks. Yields of herbage dry matter were increased by increasing the nitrogen application rate and by splitting the total amount of fertilizer nitrogen into either three or four equal dressings. The mean crudeprotein content of the herbage dry matter was increased by increasing the nitrogen application rate, but it was reduced by splitting the total amount of fertilizer into several dressings. The nitrate content of the herbage was higher after a single heavy dressing of fertilizer nitrogen than after several split dressings. It is concluded that the optimum application programme for a total rate of 100 lb nitrogen/acre was three split dressings each of 33J lb/acre, and for the 200 and 300 lb nitrogen/acre rate, four split dressings of 50 and 75 lb/acre respectively.