长期施肥对黄壤性水稻土综合肥力和水稻产量的影响

Effects of long-term fertilization on integrated fertility and rice yield in yellow paddy soil

【目的】评价长期不同施肥处理对西南地区黄壤性水稻土综合肥力和水稻产量的影响,为西南稻区土壤培肥和作物产能提升提供科学参考。【方法】依托农业农村部贵州耕地保育与农业环境科学观测实验站的长期定位试验,选取10个不同施肥处理:不施肥(CK)、单施氮肥(N)、施氮磷肥(NP)、施氮钾肥(NK)、施磷钾肥(PK)、平衡化肥(NPK)、25%有机肥替代化肥(3/4NP+1/4M)、50%有机肥替代化肥(1/2NP+1/2M)、单施有机肥(M)、有机肥化肥配施(NPK+M),测试各处理2016—2020年作物产量和耕层土壤养分,运用改进的内梅罗指数法对土壤综合肥力进行估算,采用随机森林回归评估土壤性质对综合肥力的影响,基于稳定性指数和可持续性指数评估不同施肥管理下水稻产量的稳定性和可持续性特征,通过路径分析明确施肥对土壤肥力和作物产量的影响。【结果】长期不同施肥处理对黄壤性水稻土综合肥力有明显影响,土壤综合肥力指数以N处理最低,NPK+M处理最高;长期施用有机肥各处理(3/4NP+1/4M、1/2NP+1/2M、M、NPK+M)的土壤综合肥力指数显著高于CK和施化肥处理(N、NP、NK、NPK)(P<0.05,下同)。随机森林回归结果表明,土壤有效磷和有机质含量是影响土壤综合肥力指数的重要影响因素,相对重要性分别为32.1%和25.0%。水稻产量结果表明,有机肥部分替代化肥(3/4NP+1/4M和1/2NP+1/2M)和NPK+M处理的水稻产量显著高于CK、N和NK处理。施用有机肥各处理(3/4NP+1/4M、1/2NP+1/2M、M、NPK+M)在获得水稻高产的同时,水稻产量的稳定性和可持续性也较高;CK、N和NK处理水稻产量较低,且产量稳定性和可持续性低。土壤综合肥力指数与水稻产量密切相关,路径分析结果表明,长期施用磷肥和有机肥促进了黄壤性水稻土综合肥力提升,并促进作物增产;当季施用氮肥和磷肥促进水稻增产。【结论】长期施用有机肥和磷肥可提升黄壤性水稻土综合肥力,并维持水稻高产、稳产和可持续性。土壤有效磷和有机质含量是影响黄壤性水稻土综合肥力高低的重要养分指标。

【Objective】To evaluate the effects of long-term different fertilization treatments on the comprehensive fertility and rice yield of yellow paddy soil in southwest China,and to provide scientific reference for farmland soil fertilization and crop productivity enhancement in southwest China.【Method】The study was based on the long-term fertilization experiment by the Scientific Observing and Experimental Station of Arable Land Conservation and Agricultural Environment(Guizhou),Ministry of Agriculture and Rural Affairs.The ten fertilization treatments includedno fertilization(CK),single application of nitrogen fertilizer(N),nitrogen and phosphorus fertilizer(NP),nitrogen and potassium fertilizer(NK),phosphorus and potassium fertilizer(PK),balanced fertilizer(NPK),25%organic fertilizer replacement fertilizer(3/4NP+1/4M),50%organic fertilizer replacement fertilizer(1/2NP+1/2M),single application of organic fertilizer(M),combined application of organic fertilizer and chemical fertilizer(NPK+M).The rice yields and top soil properties collected from 2016 to 2020 were measured,and the change trends of soil fertility was assessed using the improved Nemoro index(IFI).Random forest regression was used to assess the importance of soil property indexes on integrated soil fertility.The stability and sustainability characteristics of rice yield under different fertilization management were assessed based on stability index and sustainability index,and the effect of different fertilizer applications on soil fertility and crop yield was clarified by path analysis.【Result】Long-term different fertilizer managements had obvious effects on integrated fertility(IFI)in yellow paddy soil.The lowest IFI was in the treatment N and the highest in the treatment NPK+M.The IFI of each treatment with long-term application of organic fertilizer(3/4NP+1/4M,1/2NP+1/2M,M,NPK+M)were significantly higher than CK and each treatment with chemical fertilizer(N,NP,NK,NPK)(P<0.05,the same below).Random forest regression analysis showed that soil available phosphorus and soil organic matter content were important influencing factors on soil integrated fertility index,with relative importance of 32.1%and 25.0%,respectively.The results of rice yield showed that the rice yield of partial replacement of chemical fertilizer by organic fertilizer(3/4NP+1/4M and 1/2NP+1/2M)and NPK+M were significantly higher than those of treatments CK,NK and N.Rice yield stability and sustainability were higher in each treatment(3/4NP+1/4M,1/2NP+1/2M,M,and NPK+M)with organic ferti-lizer application while achieving high yields;rice yields were lower in the CK,N,and NK treatments and yield stability and sustainability were lower.Soil integrated fertility index was closely related to rice yield.The path analysis showed that long-term application of phosphorus fertilizer and organic fertilizer promoted the integrated fertility of yellow paddy soils and increased crop yield;short-term application of nitrogen fertilizer and phosphorus fertilizer promoted rice yield increase.【Conclusion】Long-term application of organic fertilizer and phosphorus fertilizer improves soil integrated fertility of yellow paddy soil,and maintain high,stable and sustainable rice grain yield.Available phosphorus and soil organic matter are the most important soil indicators affecting the integrated fertility of yellow paddy soil.