IFDC Report, Volume 5, No. 2
This report provides an overview of the collaborative research project between the International Fertilizer Development Center (IFDC) and the International Rice Research Institute (IRRI) to improve the efficiency of nitrogen fertilizers applied to rice. The initial phase of the research focused on irrigated rice and determining the magnitude of fertilizer nitrogen losses. Several experiments using the isotope 15N were conducted at IRRI, and data from these experiments are currently being processed. The research has been extended through a network of 15N experiments in India, Thailand, and Korea. The findings suggest that fertilizers producing high concentrations of dissolved ammonium in floodwater are inefficiently utilized by the rice plant, leading to significant losses through ammonia volatilization. The study also compared different fertiliser application methods and found that the best-split system, deep placement of supergranules, and slow-release fertilizers showed promise in improving nitrogen efficiency. The research revealed variations in the effectiveness of nitrogen application methods between wet and dry season crops. Root-zone placement of urea supergranules was the most effective method overall. The study also explored nitrous oxide fluxes and their implications for nitrogen loss due to denitrification. Additionally, the report discusses other research conducted at IRRI, including the impact of deep-placed urea supergranules on nitrogen-fixing blue-green algae in rice paddies, the development of integrated nitrogen management for rice-growing soils, and the evaluation of polymer-coated urea as a slow-release fertilizer. Furthermore, the report provides updates on IFDC staff involved in the project, training programs for cooperators in the International Network on Soil Fertility and Fertilizer Evaluation for Rice (INSFFER), and a fertilizer equity study conducted in Bangladesh to assess the distribution and impact of fertilizer use among small farmers and sharecroppers.