秸秆及其生物炭还田对水稻养分吸收分配和产量的影响

Effects of Straw and Its Biochar Returning on Uptake and Distribution of Rice Nutrients and Rice Yields

【目的】研究秸秆和秸秆生物炭还田对土壤肥力、水稻养分吸收分配以及产量构成因素的影响,以期揭示不同还田措施影响水稻养分吸收分配以及产量的主导因素,为科学合理施用秸秆和秸秆生物炭提供理论依据和技术指导。【方法】以第四纪红色黏土母质发育而成的红壤性水稻土为供试土壤,盆栽试验设置3个处理:单施化肥(NPK);化肥配施秸秆(NPK+S);化肥配施生物炭(NPK+B)。在水稻成熟期,采集植株和土壤样品。分析土壤养分含量、水稻植株各部位干物质量以及其氮、磷、钾养分含量的变化,研究植株养分在各部位的分配规律,并通过PLS-PM模型揭示影响水稻产量的主导因素。【结果】秸秆和秸秆生物炭还田显著提高了土壤有机碳、全氮和速效钾含量,而且秸秆生物炭还田处理土壤有机碳和全氮含量显著高于秸秆还田处理(P<0.05),分别提高29.05%和8.95%。水稻分蘖前期NPK+B处理分蘖数高于NPK和NPK+S处理,但分蘖后期最大分蘖数呈NPK>NPK+B>NPK+S的趋势。较NPK处理,NPK+B和NPK+S处理均显著提高地上部干物质量,尤其是穗部干物质量(P<0.05),其中NPK+B处理效果较佳。NPK+B和NPK+S处理水稻植株叶、穗部氮、磷养分含量较NPK处理总体均呈增加趋势,且促进了氮、磷素向植株地上部转移以及钾素向茎叶的转移。较NPK处理,NPK+B和NPK+S处理显著提高了每穗粒数、结实率、成穗率(P<0.05),增幅分别为40.33%、19.38%、17.68%和42.32%、10.93%、17.24%。PLS-PM模型分析结果显示,植株氮、钾素的养分分配变化主要通过提高产量构成因素的每穗粒数、结实率、成穗率进而显著提高水稻产量(P<0.05)。【结论】秸秆和秸秆生物炭还田提高了土壤有机碳、全氮、速效钾含量,进而影响了植株各部氮、磷、钾养分含量以及其养分分配,而土壤肥力变化调控的植株氮、钾养分分配是影响水稻产量变化的主导因子。

[Objective]Effects of straw and its biochar returning on soil fertility,nutrient uptake and distribution of rice and yield components was investigated to reveal the dominant factors affecting rice yield under different treatments,which would provide a theoretical basis and technical guidance for scientific and rational application of straw and its biochar[.Method]The red paddy soil developed from the parent material of Quaternary red clay was used as the test soil.Three treatments were designed as follows:chemical fertilizer(NPK),NPK combined with straw(NPK+S),NPK combined with biochar(NPK+B).Plant and soil samples were collected at rice maturity stage.The changes of soil nutrient contents,dry matter accumulation and nitrogen,phosphorus and potassium contents in different parts of rice plant were analyzed.Moreover,the distribution pattern of plant nutrient in different parts was also investigated and the dominant factors affecting the rice yield were revealed by PLS-PM model.[Result]Straw and straw biochar returning significantly increased the contents of soil organic carbon(SOC),total nitrogen(TN),available potassium(AK),and the contents of SOC and TN in NPK+B treatment were significantly higher than those in NPK+S treatment(P<0.05),which was increased by 29.05%and 8.95%,respectively.The tiller number of NPK+B treatment was higher than that of NPK and NPK+S treatments in the early tillering stage of rice.However,the maximum tiller number in the late tillering stage showed a trend of NPK treatment>NPK+B treatment>NPK+S treatment.Compared with NPK treatment,both NPK+B and NPK+S treatments significantly increased the aboveground dry matter accumulation,especially in the panicle parts(P<0.05),with NPK+B treatment presenting a better effect than NPK+S treatment.NPK+B and NPK+S treatments showed an increase in the contents of nitrogen(N)and phosphorus(P)in leaves and panicles of plants,and promoted the transfer of N and P to the aboveground parts of plants and the transfer of K to stems and leaves.Compared with NPK treatment,NPK+B and NPK+S treatments significantly increased grain number per panicle,seed setting rate and panicle formation rate(P<0.05)by 40.33%,19.38%,17.68% and 42.32%,10.93%,17.24%,respectively.The effects of changes in soil nutrients,plant nutrient distribution and yield components on rice yield was analyzed by PLS-PM model.The results showed that the changes in nutrient allocation of N and K in plants mainly increase rice yield by increasing the number of grains per panicle,seed setting rate and panicle formation rate of yield components(P<0.05).[Conclusion]Straw and its biochar returning increase the contents of SOC,TN and AK,which influence the contents of N,P and K in each part of plants and their nutrient distributions.The allocations of N and K in plants regulated by soil fertility change were the dominant factors influencing rice yield.