氮肥施用对直播冬油菜产量及氮肥利用率的影响

为探明安徽省直播冬油菜种植中适宜的氮肥用量、氮肥种类和施氮方式，通过田间小区试验，研究尿素不同用量及等氮量尿素和控释尿素不同施用方式对直播冬油菜产量、氮肥累积量及氮肥利用率的影响。结果表明：施氮水平和施氮方式对直播冬油菜产量具有显著影响，成株率与产量之间呈显著正相关，施氮量180 kg N·hm^-2条件下，尿素分次施用处理（N180）和控释尿素一次性施用处理（CRU180）在生育中后期能有效提高直播冬油菜密度。施氮量240 kg N·hm^-2、尿素分次施用处理（N240）角壳和茎秆氮素累积量分配比例增加，籽粒分配比例减少，氮肥表观利用率、氮肥农学效率、氮肥生理效率和氮肥偏生产力显著降低，籽粒产量不增反降，较CRU180和N180分别降低2.87%和9.67%。各施氮处理中，N180处理产量最高，较其他施氮处理显著增产7.53%~82.15%。施氮量180 kg N·hm^-2条件下，相比尿素一次性施用处理（U180），CRU180和N180显著增产8.53%和16.69%，籽粒氮素累积量显著增加8.80%和16.02%，氮肥表观利用率显著增加11.68%和14.30%，氮素农学效率显著增加12.53%和24.46%，氮素生理效率增加0.74%和9.13%，氮肥偏生产力显著增加8.59%和16.76%。综合本试验直播冬油菜产量、氮素累积量和氮肥利用率结果来看，合理的氮肥用量和氮肥品种可以有效增加直播冬油菜的成株率和氮素累积量，进而增加产量、提高氮肥利用率。安徽省直播冬油菜施氮量180 kg N·hm^-2，尿素分次施用和控释尿素一次性施用，均能达到产量和氮肥利用率的双向提升。考虑到直播冬油菜轻简化发展大趋势，建议采用控释尿素一次性基施。

Effect of nitrogen application on yield and nitrogen fertilization efficiency in direct-sown winter oilseed rape(Brassica napus L.)

The aim of this study is to investigate the reasonable dosage of nitrogen fertilizer, nitrogen fertilizer type and application methods for direct-sown winter oilseed rape(Brassica napus L.) in Anhui Province. A field experiment was conducted to study the yield, nitrogen accumulation and nitrogen fertilization efficiency in direct-sown winter oilseed rape with different urea application dosages, different application methods of urea and controlled-release urea at the same dosages. The results showed that there were significant effects of N application dosages and methods on yields of direct-sown winter oilseed rape. The manure plant rate had a significant positive correlation with the rape seed yield. Split application urea(N180) and one-off fertilization of controlled-release urea(CRU180) at the same N fertilizer amount (180 kg N·hm^-2)increased the density at the middle and later stages of direct-sown winter oilseed rape. The high nitrogen rate(N240) increased the distribution proportion of nitrogen accumulation in shell and stem, decreased the proportion in seed and significantly decreased the recovery efficiency of applied N(REN), the agronomic efficiency of applied N(AEN), the N physiological efficiency(PEN) and the nitrogen partial factor productivity(PFPN). Compared with the treatments of N180 and CRU180, the yields of N240 decreased by 2.87% and 9.67%, respectively. Compared with other nitrogen treatments, the highest yield was N180, which significantly increased by 7.53%~82.15%. Compared with the one-off fertilization of 180 kg N·hm^-2 urea(U180), the yields, N accumulation of seed, REN, AEN, PEN and PFPN of CRU180 and N180 increased significantly by 8.53% and 16.69%, 8.80% and 16.02%, 11.68% and 14.30%, 12.53% and 24.46%, 0.74% and 9.13%, 8.59% and 16.76%, respectively. The rational nitrogen application dosage and application methods could increase the mature plant rate and N accumulation of direct-sown winter oilseed rape, which further increased the yield and nitrogen use efficiency. Based on the yields, nitrogen accumulation and nitrogen use efficiency, the optimum N fertilizer application dosage in Anhui Province was found to be 180 kg N·hm^-2, which included N180 and CRU180. Considering the labor cost of topdressing fertilizer, one-off fertilization of controlled-release urea is an alternative N management for direct-sown winter oilseed rape.