减氮配施控释尿素对水稻产量和氮肥利用的影响

以释放期为60~90 d的控释尿素为试验材料,2015年在广东省台山市和翁源县开展大田试验,研究在全量施氮195 kg(N)·hm~(-2)]、减氮20%156 kg(N)·hm~(-2)]和减氮40%117 kg(N)·hm~(-2)]条件下,常规分次施肥(CF)、配施控释尿素氮占25%一次性施用(25%CRU)和配施控释尿素氮占50%一次性施用(50%CRU)对水稻生长、产量及氮肥利用率的影响,为控释尿素在水稻生产上的推广应用提供参考。结果表明,在水稻营养生长阶段,不同施氮处理的每兜分蘖数基本一致,叶片SPAD值随施氮量增加略有提高。随着施氮量增加,水稻产量先提高后降低,当施氮量为156 kg(N)·hm~(-2)时,水稻产量最高。等氮条件下,25%CRU、50%CRU和CF处理的水稻籽粒产量基本一致;不同施氮处理的稻谷和稻草氮素吸收累积量无显著差异。水稻氮素吸收累积量随着施氮量的增加而增加,而氮肥偏生产力和氮收获指数逐渐降低。等氮条件下,25%CRU和50%CRU处理的氮肥农学效率、氮肥生理利用率均显著高于常规施肥处理(P(27)0.05),两地平均增幅分别为14.99%、17.23%和98.22%、57.44%。当施氮量为195 kg(N)·hm~(-2)时,25%CRU和50%CRU处理的氮收获指数较常规施肥处理(CF)提高6.99%和6.69%,其中台山试验点的增幅达到显著水平(P(27)0.05)。117 kg(N)·hm~(-2)处理的土壤碱解氮含量显著降低(P(27)0.05)。25%控释氮肥掺混一次性施用施氮量为156 kg(N)·hm~(-2)的施肥处理,其产量和氮肥利用效率在台山和翁源两个试验点均较高,在广东省双季稻区可实现水稻增产稳产,显著提高氮肥利用率,并维持土壤肥力,是一种较优的氮肥运筹模式。

Effect of combined application of controlled-release urea and conventional urea under reduced N rate on yield and N utilization efficiency of rice

The effects of different blending rates of controlled-release urea (CRU) and conventional urea (CU) at different nitrogen (N) application rates on the growth, yield, N uptake and N use efficiency of rice were studied to provide a reference base for the ap-plication and dissemination of CRU in rice production. Field experiments of rice were carried out in Taishan City and Wengyuan County in Guangdong Province during the 2015 rice growing season. Ten treatments were set in the experiment— conventional fertilization with 4 split applications (CF), single basal application of 25% CRU plus 75% CU (25%CRU) and single basal applica-tion of 50% CRU plus 50% CU (50%CRU), respectively, under 100%, 80% and 60% of conventional N rate 195 kg(N)·hm-2, 156 kg(N)·hm-2 and 117 kg(N)·hm-2], and no nitrogen fertilization (CK). Tiller number and leaf SPAD values were measured at vegeta-tive stages of rice. Straw and grain yield were collected at maturity for N analysis. Then yield and yield components were recorded after harvest. The results showed that there was no difference in tiller number at vegetative growth stages under different N fertiliza-tion treatments, and that leaf SPAD increased with increasing N application rate. With increasing N application rate, rice grain yield increased initially and then decreased. Also the highest rice grain yield was obtained under 156 kg(N)·hm-2 treatment. N uptake of rice increased with increasing N application. At the same N rate, no differences was noted in grain yield, N uptake of rice grain and rice straw among CF, 25%CRU and 50%CRU treatments. With increasing N application rate, N partial factor productivity and N harvest index decreased gradually. For the same N rate, agronomic N use efficiency, N physiology efficiency under 25%CRU and 50%CRU treatments were higher than that under CF treatment (P<0.05), with average increases of 14.99%, 17.23% and 98.22%, 57.44%, respectively. N harvest indices under 25%CRU and 50%CRU treatments were averagely higher by 6.99% and 6.69%, re-spectively, than that under CF treatment at conventional application rate 195 kg(N)·hm-2], especially in Taishan City. Soil available N under 60% conventional N rate 117 kg(N)·hm–2] treatment after rice harvest was significantly lower than that under 100% and 80% conventional N rate treatments. In conclusion, rice grain yield and N use efficiency under 25%CRU at 80% conventional N rate in both experiment sites were superior over those under other treatments. Therefore, single basal application of 25%CRU plus 75%CU with N rate of 156 kg(N)hm-2 increased rice yield and N use efficiency, and maintained soil N fertility in Guangdong. This was a potential beneficial and rational N application mode for the region.