不同施肥措施对稻田氮损失和氮肥利用的影响

通过田间原位和微区同位素试验，研究不同施肥措施对水稻生长、氮肥利用和氮素损失的影响，并从土壤氮素转化探究其影响机制。结果表明：（1）与常规表施CT处理相比，尿素深施DT和尿素深施下配施有机肥DT+M显著降低土壤15N-NH3排放，DT和DT+M的15N -NH3排放因子分别为0.19%和0.37%，比CT分别降低95.8%和91.7%。（2）与表施相比，氮肥深施显著提高了植株地上部和根系对15N的吸收，减少了15N的损失。不同施肥措施中，DT+M的15N损失最小，比CT低48.7%。（3）深施能够增强土壤对NH4+-N的固定，显著提高氮肥利用率，DT和DT+M的氮肥利用率较CT分别增加了69.8%和59.1%。此外，深施还有助于水稻产量的提高，但DT处理的增产效果受环境条件的影响，而DT+M处理增产作物较为稳定。

Effects of Different Fertilization on Nitrogen Loss and Use Efficiency in Rice Field

The effects of different fertilization on rice growth, nitrogen use efficiency and loss were studied by in-situ and micro-area isotope experiments, and the mechanism was explored through the nitrogen transformation. The results show as follows:1) Compared with conventional surface application (CT), urea deep placement (DT) and urea deep application combined with organic addition (DT+M) significantly decrease ¹⁵N -NH₃ emission. The emission factors in DT and DT+M are 0.19% and 0.37%, which are 95.8% and 91.7% lower than that in CT, respectively. 2) Compared with CT, nitrogen deep application significantly increases the uptake of ¹⁵N from rice plant and root, and reduces the loss of ¹⁵N. DT+M has the lowest ¹⁵N loss among the different fertilizer treatments, which is 48.7% lower than that of CT. 3) Nitrogen deep application can enhance the fixation of soil NH₄⁺-N and increase nitrogen use efficiency. DT and DT+M increase nitrogen recovery efficiency by 69.8% and 57.1% compared with CT, respectively. In addition, DT also contributes to the increase of rice yield, but it is affected by environmental conditions. By contrast, DT+M gives a stable increase of rice yield.