Impact of Locally Derived Organic Materials and Method of Addition on Maize Yields and Nitrogen Use Efficiencies in Major and Minor Seasons of Tropical South Asia

Abstract

Maize is the most important highland cereal grown in the tropics, generally cultivated under rainfed smallholder conditions in Asia. Field experiments were carried out in Sri Lanka with the objective of determining the impact of three types of organic matter applied as mulch or incorporated on the yields and nitrogen uptake by maize cultivated under rainfed conditions in the South Asian major and minor seasons. The organic matter used was leaves of Gliricidia sepium, Tithonia diversifolia, or rice straw, with the full compliment of recommended mineral fertilizers. Organic matter, especially the two green manures, enhanced yields and nitrogen (N) uptake of maize, and the impact was more prominent in the minor dry season where the yields were lower. Incorporation of organic matter had a greater positive impact in the dry season in terms of N utilization efficiency and seed yields. The beneficial impact of organic matter with low carbon (C):N ratios in enhancing N nutrition and seed yields of rainfed maize in major and more importantly in the minor seasons is presented.