Effect of Urea application on phytoplankton activity and nitrogen losses in rice field
2004
Ngo Ngoc Hung
Poor N fertilizer-use efficiency is characteristic of rice cultivation system. As documented, low efficiency is largely attributed to rapid losses of applied N from NH3 losses - water pH is a major determining factor, from which photosynthetic aquatic biomass has a key role in increasing the floodwater pH. The research was conducted on alluvial soil at Chau Thanh, Can Tho during wet season 2002. The biomass of phytoplankton reached maximum within 2-4 days after urea application. The biomass of phytoplankton at the CuSO4 treatment was lower than that of the control. Algaecides are suggested to test for reducing NH3 volatilization loss. The noticeable amount of ammoniacal-N can remain in floodwater within 6-7 days after fertilization. Consideration of the floodwater N concentration will greatly help minimize N losses by leaching or run-off from lowland rice soils.
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