Improved fertilizers for developing countries : agronomic research, progress report

The present project is our expansion of the previous project, which was restricted to the use of fertilizer for rice, in that new and improved fertilizers are to be tested on a number of tropical crops. In addition to actual agronomic evaluations of new materials, increased emphasis is placed on developing and demonstrating methods of introducing new fertilizers to farmers so that they will be properly used or they become commercially available. Additional data has been received from a number of countries pertaining to the use of SCU for rice. In general, these data tend to substantiate those previously reported in that SCU is a superior source of N for rice grain under conditions of intermittent flooding, but that it is no better than conventional sources of N when conditions of intermittent flooding or severe leaching do not exist. A discussion of the commercial potential of SCU in tropical agriculture follows this section. Insufficient data are available for tropical crops other than rice to warrant any general conclusions at this time.