关键词: 水稻, 尿素, 以水带肥深施, 氮肥效率

Abstract:

The paper offers a very simple, practical and efficient technique for deep placement of urea topdressed in irrigated rice fields. The technique combines N fertilizer application method with soil moisture regime control. The specific way to use the technique is that urea as N fertilizer was topdressed on rice fields, where moisture regime had become unsaturated by cutting off the water supply and draining, then irrigation should be immediately done after application of urea to make the fertilizer deep placement in reduced zone with downward infiltrating water. The results obtained in the study, which consists of soil column experiment, pot experiment and field experiment, show that fertilizer nitrogen efficiency can be substantially increased with the technique, which resulted in more than 60% of topdressed urea deep-placed in reduced zone and minimized its N-losses. As compared the technique with conventional broadcasting N fertilizer on flooded rice field, 1.5 kg N/mu (22.5 kg N/ha) can be saved to get the comparable high yield (around 7.4 t /ha) and significantly higher yield can be obtained at an equal N level of 7.5 kg/mu.

Key words: rice, urea, deep placement of N fertilizer by water, nitrogen efficiency