Irrigation of grassland

Abstract

Field experiments are described comparing the yield of herbage on a series of grass-clover plots which were irrigated after various deficits had developed. In addition to the irrigation treatments, different rates of nitrogen were applied. The maximum yields were obtained when only small deficits were allowed (maximum pF 3·3). This applied particularly to grass-clover swards to which no nitrogen fertilizer was applied. There was not much reduction in yield on predominantly perennial ryegrass swards liberally supplied with nitrogen when larger deficits were allowed to develop (pF c. 4·0). Estimates of soil water deficit from meteorological data using Penman's method agreed very well with direct measurements.