施氮量和田面水含氮量对紫色土丘陵区稻田氨挥发的影响

Effects of Nitrogen Rate and Field Water Nitrogen Content on Ammonia Volatilization from Paddy Field in a Purple Soil Hilly District

采用密闭室连续抽气法研究了四川省丘陵区紫色土上不同施氮量条件下（0、112.5、150、187.5、225 kg/hm2）稻田氨（NH3）挥发特征及田面水含氮量对其的影响。结果表明,施氮肥后的1~3天内出现NH3挥发峰值,随后逐渐下降。稻田NH3挥发总量随施氮量的增加而增加,二者呈极显著的相关关系（r=0.916 6＊＊＊）。通过稻田NH3挥发损失的氮素占施氮量的比例为29.4%~38.0%。施氮肥后稻田田面水NH4＋-N、可溶性氮和总氮浓度均迅速升高,稻田NH3挥发速率与田面水中的NH4＋-N、可溶性氮和总氮浓度均具有显著的相关关系,观测期内的最高相关系数分别为0.926 9、0.841 2和0.881 3。因此,控制施氮量可有效降低田面水NH4＋-N、可溶性氮和总氮浓度,以此来减少紫色土丘陵区稻田NH3挥发损失。

The effects of different N application rates （0, 112.5, 150, 187.5, 225 kg/hm2）, as well as paddy field water N content on NH3 volatilization characters were studied in a paddy field in the purple soil district by using a closed air-flow chamber method. The results indicated that NH3 volatilization rate peaked during the first 1 - 3 days after N fertilizer application and decreased gradually thereafter. Higher NH3 volatilization rates were observed in the high N application treated plots. The amount of NH3 volatilization during the observation duration increased with the increase of N fertilizer application rate. Significantly correlativity （y = 0.312 3 x ＋ 24.712 9, r = 0.916 6＊＊＊） was found between NH3 volatilization and N fertilizer application rate. The ratio of N loss via NH3 volatilization to N fertilizer application rate ranged within 29.4% - 38.0%. NH4＋-N, dissolved N and total N concentrations in field water which showed a sharp increase after N fertilizer application were highly related to NH3 volatilizatio.n, with the highest correlation efficient 0.926 9, 0.841 2 and 0.881 3, respectively. Improved fertilizer application techniques such as incorporation of organic material with chemical fertilizer, utilization of controlled release chemical fertilizers and N fertilizer management during the rice growing season are required to decrease NH4＋-N, dissolved N and total N concentrations in field water to mitigate NH3 volatilization in paddy field in the purple soil hilly district.