水稻减氮施肥综合效益研究

通过对江山市单季稻生产用氮量进行的调查,结果平均用氮量是240kg/hm2,显著高于中国稻田单季用氮量。过度的用氮不仅造成生产成本高、效益低,也降低了氮肥利用率和稻米的品质,并污染了环境。为此,2005年开展了减氮处理试验,减幅为调查平均数的10%￣30%,试验结果表明:当减氮15%￣25%时,水稻产量比不减氮的增产27%左右;氮肥利用率随着用氮量的增加而降低,变化幅度20.7%￣46.9%;而氮流失量与用氮量的高低同步,随着氮量的增加而增加,变化幅度32.1￣80.1kg/hm2;有害物质——亚硝酸盐含量和氮流失量一样,与用氮量成正相关关系。以上表明,在水稻生产中,农户存在用氮过量的现象,应引起相关部门的重视,提倡农户减少施氮量。

Study on Comprehensive Utilization Efficiency of Reducing Fertilizer Nitrogen for Rice

Through our investigation on the amount of N fertilization in Jiangshan single season later-rice production, we have found that average rate of N application per hectare was 240kg in 2004, over the average rate of China. So rice cost of production was high and N-fertilizer use efficiency was low. Furthermore, environmental pollution by nitrogen leaching or runoff from rice fields has become a serious concern, rate from investigation with it has been reduced from 10%~30%, and were used to study yields of rice, quality of rice, N-fertilizer use efficiency and N loss rates in 2005.The result showed that compared with custom of farmers used N-fertilization, rice yields increased about 27% with the N-fertilization reduced from 15%~25%. N-fertilizer use efficiency changed in the range of 20.7%~46.9% with the amount of N-fertilization applied, the more the N used, the lower N-fertilizer use efficiency. N loss rates and the amount of N-fertilization applied kept same step, N loss rates per hectare changed in the range of 32.1kg~80.1kg, the more the N used, the more N loss rates, and nitrite content of rice too. It shows that many farmers use excessive N rates in single season later-rice production. We should reduce it.