Nitrogen fertilizer and wheat in a semi-arid environment. 1. Effect on yield

Abstract

Response experiments with Gabo wheat at four rates of ammonium sulphate (0, 11.5, 23, and 46 lb N an acre) were carried out at a number of widely-spread locations in the cereal growing areas of South Australia during six seasons in the period 1956-61. Considerable variability in grain and grain + straw yield and in the observed response to nitrogen fertilizer was found. Season and site effects were marked and season-site interactions were also observed. The mean grain yield response was 8.7, 7.2, and 5.1 lb grain for each lb of nitrogen applied as fertilizer at the rates of 11.5, 23, and 46 lb N an acre. These mean values are lower than those reported for other more humid wheat growing areas, but there are conditions where response is at a comparable level. The main difficulty lies in predicting these situations. Several aspects of the use of nitrogen fertilizer in a semi-arid environment are discussed.