Dryland wheat yields in relation to soil organic carbon, applied nitrogen, stored water and rainfall distribution

Abstract

Correlations of long-term yields with soil, climatic and management variables would increase our understanding about their contribution to yield and help balance them for optimising the same. Therefore, grain yields of dryland wheat which received variable N ranging from 0–100 kg ha−1 collected over 13 years, were analysed statistically. Wheat responded significantly to applied N in all but two years when the yields were the lowest. Grain yields across years did not relate with applied N alone (r2 = 0.00), but inclusion of seasonal water supply and organic carbon content of soil (OC) in the regression accounted for 64 per cent variation in yield. When water supply was split into stored water and growing season rain the relationship improved further (R4 = 0.68) and the regression exhibited a significant interaction between seasonal rain and applied N.