IFDC Report, Volume 4, No. 3

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Nitrogen fertilizer plays a crucial role in achieving high-yielding rice crops. However, the current practice of broadcasting urea on the surface of floodwater in Asia is inefficient. To address this issue and explore better methods of nitrogen fertilizer application, the International Network for Soil Fertility and Fertilizer Evaluation in Rice (INSFFER) was formed by 10 Asian countries in collaboration with the International Rice Research Institute (IRRI) and the International Fertilizer Development Center (IFDC). Early results from INSFFER experiments indicate that slow-release fertilizers, such as sulfur-coated urea, and deep placement using urea supergranules, are generally effective in increasing nitrogen fertilizer efficiency for rice. However, in specific locations and seasons, these methods have proven to be ineffective. To better understand the fate of fertilizer nitrogen in soil-plant systems, a mini-network experiment utilizing the stable isotope 15N was established. The mini-network experiments involve labelling fertilizer with 15N and carefully analyzing nitrogen and 15N levels in soil and rice crops at various time intervals after application. Indirect estimation of nitrogen losses will be derived from the 15N balance in the plants and soil. The data obtained from these experiments will provide valuable support to INSFFER's agronomic studies, enabling determining the effects of fertilizer source and management on nitrogen efficiency in diverse rice-growing environments. The experimental design for the mini-network experiments was developed during a meeting attended by scientists from India, Korea, Thailand, China, IRRI, and IFDC. The success of the 15N balance experiments relies on strict adherence to correct analytical procedures, and the 15N samples will be analyzed in IFDC laboratories. The report also highlights other research initiatives by IFDC, such as the economic evaluation of phosphate rock sources for direct application in food crop production, the utilization of Eppawala phosphate rock from Sri Lanka, and the development of a phosphate fertilizer program in Upper Volta. Furthermore, it discusses the training programs conducted by IFDC, including the fertilizer marketing and distribution course, aimed at enhancing managerial capabilities in developing countries.
Phosphate fertilizers, Rock