沼液在稻田的精确施用及其环境效应研究

为探究沼液在稻田中的适宜用量,通过田间试验,研究不同氮素水平的沼液(0、90、157.5、225、292.5、562.5 kg·hm~(-2))对水稻产量、氮素利用率、田面水无机氮动态变化、土壤残留无机氮以及稻田氨挥发的影响。结果表明,水稻籽粒产量随沼液氮素施用量的变化符合线性加平台模型,沼液在水稻种植中的最佳氮素施用量为213.9 kg·hm~(-2);施用沼液显著增加了田面水铵态氮浓度,施用沼液3 d后,田面水铵态氮浓度迅速降低,而田面水硝态氮初始浓度无明显变化;稻田氨挥发总量随沼液氮素施用量的增加而显著增加,且主要集中在沼液施用后的一周内,氨挥发所引起的氮素损失占沼液氮素量的14.52%~17.64%;等氮量施用的沼液和化肥相比,水稻产量、氮素利用率、氮素农学生产率和土壤残留无机氮均无显著差异,而单位稻谷产量的氨挥发量显著降低22.6%。由此可见,稻田合理施用沼液具有较好的经济效益和环境效益。

Precision application of biogas slurry and its environmental effects in paddy fields

A field experiment was conducted to study the effects of biogas slurry application on rice yield, nitrogen(N) use efficiency, surface water mineral nitrogen(N_min) dynamics, soil N_min, and ammonia volatilization. The results showed that rice yield had a positive linear relationship with the applied biogas slurry sourced N rate when it was less than 213.9 kg·hm^-2, and rice yield could be increased by 9.05 kg per 1 kg biogas slurry sourced N applied. However, rice yield was not increased further when the biogas slurry sourced N input was higher than 213.9 kg·hm^-2. Given this, it was indicated that 213.9 kg·hm^-2 may be the reasonable application rate for this paddy field. The soil mineral N residue increased linearly with the increase of N application rate after harvest. After the slurry application, the NH₄⁺-N concentration in the surface water was reduced rapidly, and then gradually become stable, whereas slurry application had no significant effect on NO₃^--N concentration in the surface water. Ammonia volatilization mainly happened in the first week after fertilizer application, and the N loss caused by ammonia volatilization accounted for 14.52%~17.64% of the biogas slurry sourced N application rate. Compared to chemical fertilizer application, the rice grain yield, nitrogen use efficiency, and soil N_min were similar under biogas slurry application with the same amount of N, whereas the ammonia volatilization intensity(kg NH₃ per kg rice yield) was significantly reduced by 22.6%. According to the results of this study, the rational use of biogas slurry in paddy fields could have good economic and environmental benefits.