Chapter 7 - Nitrogen use efficiency in crop production: issues and challenges in South Asia

Abstract

South Asia is home to 23.1% of the global population, and its share in global fertilizer nitrogen (N) use in 2018 was 21.63%. More than 99% of the N fertilizer consumed in the region is used by Bangladesh, India, and Pakistan, the three largest countries in South Asia. Since both food security and N-based global warming and environmental pollution are linked with fertilizer N use efficiency (NUE), it has been attempted to discuss different aspects of NUE in these three South Asian countries using datasets pertaining to N input and N output available at the Soil Nutrient Budget domain of the FAOSTAT. In 2018, total N input per unit of cropland area in Bangladesh was 40% higher than in India and Pakistan, but NUE, defined as proportion of applied N utilized by the crop plants, was 48%, 35%, and 25% in Bangladesh, India, and Pakistan, respectively. Substantially lower maximum yield of N under saturating N input regimes in India and Pakistan (53.8 and 44.3kgNha−1 year−1) than in Bangladesh (122.7kgNha−1 year−1) suggests that there is need to greatly improve fertilizer N management strategies in both India and Pakistan. Low NUE in India and Pakistan also results in high surplus N, which leads to increased risk of global warming and pollution of air and water, particularly when high fertilizer N doses are being applied by farmers to increase the crop yields. Challenges and options for increasing NUE and crop yields and reducing surplus N in South Asia are also discussed.