Effects of rainfall on nitrogen responses of spring-sown wheats

摘要

Abstract Nitrogen responses in second and third or later wheat crops in Otago and Southland were examined in relation to three rainfall criteria. When 75 kg N per ha was applied to second crops there were strong correlations between grain yield responses and total rainfall, rainfall intensity, and deviation from normal rainfall during April-June and April-September. Correlations between nitrogen responses of third or later crops and rainfall data were much weaker than those of second crops. Regressions are presented to predict responses to the application nf nitrogen fertiliser.