Interactive effect of planting date and fertiliser application on maize growth and yield under dryland conditions

Understanding the relationships among management practices during planting period will help producers to improve crop production under climate change. The interaction of planting date and soil fertility on maize yield was evaluated. Field trials were conducted during summer in 2014/15 and 2015/16 at the University of KwaZulu-Natal research farm, Pietermaritzburg, South Africa. A split-plot design was used with planting date and soil fertility as main and subplots, respectively, replicated four times. The interaction between planting date and fertility level significantly influenced plant growth and physiological parameters. The highest plant growth and physiological responses occurred in early- and mid-season planted maize during 2014/15 and 2015/16, respectively. Early planting favoured crop growth, grain yield and yield components during 2014/15 (warm season), while mid planting was the best during 2015/16 (dry season). Optimal fertiliser application has economic benefits to the farmer where it is led to increase productivity at early- and mid-planting dates during warm (2014/15) and dry (2015/16) seasons, respectively. However, optimal fertiliser application only improved plant photosynthetic activity under adequate rainfall and temperature, while minimal application of fertiliser gave higher yield returns with a mid-planting date. Longer-term experiments are needed to validate the recommendations from the current study.