机收稻草全量还田减施化肥对双季晚稻养分吸收利用及产量的影响

稻草还田替代部分化肥对推进化肥零增长行动具有重要的意义。研究等量氮磷钾养分条件下连续稻草还田减施化肥对双季晚稻产量及养分吸收利用的影响,可为南方稻区稻草资源的合理利用和水稻高产、养分高效管理提供参考。本试验基于江西温圳国家级耕地质量监测点双季稻稻草还田定位试验,以超级杂交晚稻五丰优T025为试材,设稻草还田减施化肥(SI+NPK)、稻草烧灰还田减施化肥(SB+NPK)和单施化肥(NPK)等处理,以稻草不还田不施化肥(CK)为对照,施肥处理中氮磷钾养分用量相等。研究了不同处理对双季晚稻产量、氮磷钾素养分吸收利用的影响。结果表明,在等量氮磷钾养分施用条件下,连续6年早稻稻草还田处理有利于协调双季晚稻穗粒结构,协同维持晚稻产量稳定,保持与其余施肥处理产量基本持平。与NPK相比,SI+NPK处理植株各器官中N、P、K含量及总吸收量在生育前期均较低,生育后期较高,且P、K养分吸收量差异显著;SI+NPK可显著提高水稻N、P、K养分收获指数、农学效率、回收率和养分偏生产力,而SB+NPK只比NPK显著提高了K养分收获指数、农学效率、回收率和养分偏生产力。此外,SI+NPK也比SB+NPK提高了氮、磷、钾养分收获指数、农学效率、回收率及偏生产力。总之,早稻稻草还田替代部分化肥可稳定晚稻产量水平及提高养分利用效率,实现南方稻区土壤养分资源的高效利用。

Effects of Straw Incorporation with Reducing Chemical Fertilizers on Nutrient Absorption and Utilization and Grain Yield of Double-cropping Late Rice under Mechanical Harvest

Replacing chemical fertilizer with straw incorporation is an important way to reduce fertilizer application and improve fertilizer efficiency. The objective of six year field location experiments under the same N, P, and K inputs, was to systematically explore the effects of straw incorporation and reducing chemical fertilizers on plant nutrient absorption and utilization under mechanical harvest, so as to provide a basic support for the reasonable utilization of straw resource, rice high yield and its nutrient management measure in the southern rice zone. The experiments were conducted being in the cultivated land quality monitoring station of Wenzhen town, Jiangxi province, Wufengyou T025, super hybrid late rice cultivar. Four treatments were included: total straw incorporation and reducing chemical fertilizers (SI+NPK), straw burning and reducing chemical fertilizers (SB+NPK), chemical fertilizers (NPK), and no chemical fertilizers (CK). The three fertilization treatments were with equal quantity of fertilizers (N 195 kg ha^-1, P₂O₅ 87.8 kg ha^-1, and K₂O 175.5 kg ha^-1) whatever chemical and organic ones. The variation of rice yield and nitrogen, phosphorus, potassium uptake and their utilization efficiency were determined. SI+NPK of early rice in continuous six years was avail able to balance the panicle and spikelet, and hold steady grain yield of late rice, with the same level compared with SB+NPK and NPK. Compared with NPK treatment, SI+NPK treatment had lower N, P, K contents and accumulation at the vegetative growth stage including tillering stage and panicle initiation, but higher those at the reproductive stage such as heading stage and maturity stage. Moreover, the P, K accumulation was significantly increased in SI+NPK treatment. Compared with NPK treatment, SI+NPK treatment enhanced N, P, K fertilizer harvest index, agronomy efficiency (AE), recovery efficiency (RE) and partial factor productivity (PFP) significantly, but SB+NPK treatment only enhanced K fertilizer harvest index, AE, RE, and PFP significantly. Meanwhile, compared with SB+NPK treatment, SI+NPK treatment increased N, P, K fertilizer harvest index, AE, RE and PFP. Overall, straw incorporation replacing partial chemical fertilizer of early rice, in contrast to straw burning and chemical fertilizers application, is proved to be a feasible way to stabilize grain yield of late rice, enhance nutrient utilization efficiency, and realize the efficient utilization of soil nutrient resource in the southern rice zone.