15N示踪法研究生物炭施用对水稻—土壤系统氮肥去向的影响

为探究施用水稻秸秆生物炭对水稻产量、氮肥利用率、氮肥残留及损失的影响,采用盆栽试验结合¹⁵N示踪技术,分析了施用水稻秸秆生物炭对水稻生物量、氮素积累量、肥料氮去向以及氨氧化微生物的影响。研究共设置5个处理:不施氮肥(N0)、单施化肥(CF)、施化肥配施0.5%生物炭(BC1)、施化肥配施1%生物炭(BC2)和施化肥配施2%生物炭(BC3)。结果表明:与CF处理相比,BC2和BC3处理均显著提高水稻产量,增产率分别为19.3%和22.0%。施用生物炭显著增加水稻氮素积累量和表观利用率。施用生物炭的水稻籽粒肥料氮积累和总肥料氮积累量较CF处理分别提高18.6%~23.4%和18.5%~26.5%。然而,施用生物炭处理与CF处理之间的籽粒土壤氮吸收量没有显著差异。BC1、BC2和BC3处理的氮肥利用率分别为30.4%,28.5%和29.3%,均显著高于CF处理(24.1%)。施用生物炭有利于肥料氮在土壤中的 残留,从而减少损失。因此,施用生物炭的肥料氮损失率(25.7%~27.5%)显著低于单施化肥处理(38.4%)。与CF处理相比,高量施用生物炭(BC3)显著降低氨氧化细菌的amoA基因拷贝数,但施用生物炭对氨氧化古菌丰度没有显著影响。综上表明,施用水稻秸秆生物炭是提高水稻产量和氮肥利用率,同时还是有效减少氮素损失的一种有效措施。

Effects of Biochar Application on Fate of Nitrogen Fertilizer in Rice-Soil System by the 15N Tracer Method

This study aimed to investigate the effects of rice straw-derived biochar application on rice grain yield, nitrogen use efficiency (NUE), and fate of fertilizer N. A pot experiment was conducted to assess the effects of rice straw-derived biochar application on rice biomass, N accumulation, as well as fate of urea-N using ¹⁵N tracing method and ammonia oxidizers. Five treatments were included:no N application (N0), chemical fertilizer application only (CF), CF+0.5% biochar (BC1), CF+1% biochar (BC2), and CF+2% biochar (BC3). The results showed that BC2 and BC3 treatments significantly increased rice grain yield by 19.3% and 22.0%, compared to CF treatment, respectively. Application of biochar significantly enhanced the N accumulation of rice and N apparent use efficiency compared to CF treatment. The fertilizer N uptake by grain and rice plant was 18.6%~23.4% and 18.5%~26.5% greater in biochar application than in CF treatment, respectively. While, no significant difference was observed in the soil N uptake by grain between BC treatments (BC1, BC2, and BC3) and CF treatment. The ¹⁵N use efficiency was 30.4%, 28.5%, and 29.3% in the BC1, BC2, and BC3 treatments, respectively, which were all significantly higher than that in CF treatment (24.1%). Application of straw-derived biochar increased the fertilizer N residual in soil and reduced the N loss, compared to CF treatment. Thus, the ratio of fertilizer N loss was greatly lower in BC treatment (25.7%~27.5%) than in CF treatment (38.4%). Higher application of biochar (BC3) significantly decreased the AOB amoA gene copies, compared to CF treatment. While, no significant difference was found in AOA abundance between the BC and CF treatments. Overall, application of rice straw-derived biochar is an effective practice to increase rice yield and NUE, and reduce the N loss in the rice production.