Growth, Yields, and Nitrogen-Use Efficiency of Maize (Zea mays L.) and Mungbean (Vigna radiata L. Wilczek) as Affected by Potassium Fertilizer in Tropical South Asia

Abstract

Application of chemical fertilizers in smallholder tropical farming systems of South Asia has become mandatory because of soil degradation, and nitrogen (N) is the most abundantly used nutrient. However, integrated management of N with potassium (K) could enhance productivity. Field studies tested the impact of fertilizer K on root development, seed yields, harvest indices, and N-use efficiencies of maize and mungbean, two popular smallholder crops over major and minor seasons. Application of 120 kg K ha⁻¹ optimized all parameters of maize in the major wet season, whereas the requirement was 80 kg K ha⁻¹ in the minor season. Optimal growth yields and N-use efficiencies of mungbean was with 80 kg K ha⁻¹ in both seasons. Information regarding rates of fertilizer K that optimized N use and yield of maize and mungbean during each of the two tropical monsoonal seasons of South Asia is presented.

Keywords:

• Cropping seasons
• maize
• mungbean
• nitrogen
• potassium
• tropics

Acknowledgments

Gratitude is expressed to A. Weerasinghe for field work, K. B. Attanayake for N analysis, the department of Crop Science of the University of Peradeniya for assistance and facilities, and the Group of Agronomy and Plant Breeding of the ETH, Zurich, Switzerland, for partial funding for this study. The authors express thanks to the reviewers for their useful and critical comments.