减氮条件下不同施肥措施对双季稻产量和N肥利用的影响

Effects of different fertilizations on double-rice yield and nitrogen use efficiency under the condition of reduced nitrogen application

氮(N)肥减施、作物稳产以及土壤固碳的"共赢"对于区域农业生态环境的可持续发展具有重要意义。以南方红壤性水稻土的肥料定位试验为例,研究减N(75%常规N肥)条件下不同施肥措施对双季稻田生产力和N肥农学利用效率(ANUE)的影响。试验设置对照(CK)、常规N肥(CF)、75%N肥(DF)以及在此基础上的N肥配施稻草(RS)和N肥配施粪肥(OM)等5个处理。结果表明:减N条件下DF、RS和OM处理的双季稻产量分别为7.83 t/hm2、7.26 t/hm2和8.05 t/hm2,除了OM处理明显高于CF(7.60 t/hm2)外,其余两种处理与CF相比并无显著差异。但是RS处理由于早稻的减产导致其双季稻产量显著低于DF和OM处理,而后两者之间差异不显著,说明减N条件下N肥配合粪肥施用的稳产效果优于稻草。DF处理下ANUE为13 kg/kg,较CF处理(10kg/kg)显著提高了30%。OM处理的ANUE(14 kg/kg)与DF差别不大,但是RS处理的ANUE(9 kg/kg)却较DF下降了31%,揭示减N条件下N肥配合粪肥施用能够维持N肥的农学利用效率,而稻草还田并不利于肥料N的利用。此外,与CF相比,DF处理并未降低耕层土壤有机碳(SOC)含量,而RS和OM处理下SOC含量由于有机物质的输入而增加显著。研究表明,75%的N肥施用量能够维持亚热带区双季稻的产量与耕层SOC水平,并促进肥料N的高效利用。在75%N肥施用的条件下,化肥配合粪肥施用不仅能够减少化肥N的施用量,还可维持双季稻产量和肥料N素的农学利用效率,其效果明显优于稻草。

Nitrogen （N） fertilizer reduction, crop yield sustainability and soil carbon sequestration are ＂win-win＂ strategies which are important for the sustainable development of ecological environment of regional agriculture. Based on a field experiment of red paddy soil, the effects of different fertilizations under the N reduction condition were studied on paddy soil productivity and fertilizer N agronomic efficiency （ANUE）. Five fertilizer N treatments were as follows： control （CK）, conventional N fertilizer （CF）, 75% N fertilizer （DF）, N fertilizer plus straw incorporation （RS）, and N fertilizer plus manure application （OM）. The results were as follows： the double-rice yield for treatments of DF, RS, and ON[ was 7.83 t/hm2, 7.26 t/hm2, and 8.05 t/hm2, respectively, and these values showed no significant differences with that for CF treatment （7.60 t/hm2）. However, the double-rice yield for RS was significantly lower than those for DF and OM due to its decreased early rice yield, whereas no significant difference was observed between the latter two treatments. It indicated that N fertilizer plus manure application could sustain a more stable rice yield than straw incorporation under the N reduction condition. The ANUE for DF （13 kg/kg） was significantly improved by 30% than that for CF （10 kg/kg）. As compared with DF treatment, OM could sustain the same ANUE （14 kg/kg）, whereas RS （9 kg/kg） decreased ANUE by 31%, indicating that rice straw incorporation was not conductive to the utilization of fertilizer N under the N reduction condition. In addition, soil organic carbon （SOC） content at topsoil （0-20 cm） was not decreased by DF treatment, but was further increased by RS and OM due to the organic material input. In conclusion, 75% conventional N fertilizer could sustain both double-rice yield and SOC, and further promote the fertilizer N agronomic efficiency in the subtropical region. Under the condition of 75% conventional N fertilizer, the application of chemical fertilizer plus manure application could not only reduce the chemical fertilizer N use, but also show a better effect than rice straw in sustaining double-rice yield and fertilizer N agronomic efficiency.