Alternative strategies for increasing nitrogen fertilizer efficiency in wetland rice soils [Philippines].
1981
Calabio J.C. | Garcia F.V. | Datta S.K. De
The yields of modern rice varieties increases costs of qualities of plant nutrients, particularly nitrogen. Efficiency fertilizer nitrogen used wetland rice is, however, low. The use of controlled-release and deep placement of nitrogen fertilizers are two concepts that can lead to increased fertilizer nitrogen efficiency in wetland rice. Recently- developed slow-release silica-polymer coated urea was compared with sulfur-coated urea that was developed earlier and deep placement of urea super-granules. In the 1980 dry season, the grain yields with controlled release nitrogen fertilizers and deep placed urea did not significantly differ. Both types gave significantly higher grain yields and total nitrogen uptake at harvest time than the so-called best split application -- to-thirds broadcast and incorporated before transplanting and one-third topdressed at panicle initiation. Experiments in six farmer's fields showed that proper timing of a 50 kg N/ha application matched grain yields the farmer got with 112 kg N/ha. Results further suggest that basal application of controlled - release nitrogen fertilizer such as sulfur-coated urea, and deep placement of urea supergranules, significantly increased protein content in IR9729-673 rice at a high yield level than split-applied urea. Considerable benefits in improving fertilizer nitrogen efficiency and protein content in brown rice can be obtained by using better fertilizer materials and improved management practices. Furthermore, considerable improvement in on-farm efficiency is possible by better management of fertilizers.
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