秸秆还田配施化肥对稻油轮作土壤有机碳组分及产量影响

【目的】水稻-油菜轮作是我国重要的农业种植模式。秸秆还田是目前我国秸秆利用最主要、最直接的途径。因此，研究水稻-油菜轮作系统下，秸秆还田配施化肥对水稻和油菜产量、土壤有机质组分及其养分含量的影响，有助于提高水稻和油菜产量，培肥土壤，推进秸秆还田技术的应用。 【方法】通过水稻和油菜7年13季作物的田间定位小区试验，设置了不施氮肥不还田处理（CK）、农民习惯处理（FPP）和3个秸秆还田配施化肥处理（SF1、SF2、SF3:每年水稻秸秆以3000 kg/hm2的量还田，配施不同量氮、磷、钾肥），分析了各处理土壤有机碳及其组分、土壤养分含量、作物产量和经济效益。 【结果】与不施氮肥处理比较，秸秆还田配合氮、磷、钾平衡施肥能显著提高土壤总有机碳及其各组分、土壤养分含量、作物产量和经济效益。与农民习惯处理相比，秸秆还田配施化肥处理土壤总有机碳、胡敏酸和胡敏素分别显著增加了5.62%~12.08%、9.05%~22.57%和7.93%~10.23%，而水溶性有机碳和富里酸含量差异则不明显；土壤全氮、有效磷和速效钾含量分别显著提高了6.74%~14.04%、134.67%~249.46%和40.18%~70.54%；水稻、油菜和周年平均产量分别增加了8.55%~19.34%、19.06%~27.27%和10.34%~24.08%；净利润提高了1651~4905 yuan/hm2，但总投入增加了1427~2882 yuan/hm2。秸秆还田配施化肥处理中，以氮、磷、钾肥用量与运筹次数最多的SF3处理土壤各项指标、作物产量和经济效益最高，与之相比，SF2处理在水稻和油菜两季共减少肥料用量255 kg/hm2，而作物周年产量减少不明显。土壤有机碳组分、土壤养分含量及作物产量之间有较好的相关性，而逐步回归分析表明，土壤总氮、胡敏酸、水溶性有机碳含量是水稻和油菜产量主要决定因素。 【结论】秸秆还田配施化肥可以提高土壤有机碳、胡敏酸、胡敏素含量及土壤养分含量，培肥土壤并提高其稳定性，促进作物增产。虽然秸秆还田配施化肥增加了人工和肥料投入，但适宜的化肥用量配合秸秆还田提高了水稻油菜轮作体系的经济效益。

Effects of straw returning plus fertilization on soil organic carbon components and crop yields in rice-rapeseed rotation system

Objectives] Rice-rapeseed rotation is one of the main rotation systems in China,in which large amounts of fertilizer are applied.Straw return is the most direct way to use straw in China.Therefore,studying the proper way of combined use of straw and chemical fertilizer will be beneficial to increase rice and rape yields,improve soil fertility,and promote application of the straw return technology with fertilizers in the lower Yangtze region.Methods] A field experiment was conducted consecutively for seven-years and 13 seasons in Anhui Province.Five treatments were designed including no nitrogen fertilizer no straw returning (CK),only chemical fertilizer application without straw returning as farmer's practice pattern (FPP) and three levels of fertilizer application plus rice straw return of 3000 kg/hm2 (SF 1,SF2 and SF3).The contents of soil total organic carbon (TOC) and its components,the crop yields and net benefits in rice-rapeseed rotation fields were investigated.Results] Compared with the FPP,treatments of SF1,SF2 and SF3 increased the contents of TOC,humilic acid carbon and humin carbon by 5.6％-12.1％,9.0％-22.6％ and 7.9％-10.2％,respectively,increased the contents of total nitrogen,available phosphorus and available potassium by 6.7％-14.0％,134.7％-249.5％ and 40.2％-70.5％,not increase the contents of water-soluble organic carbon and fulvic acid carbon.The average yields of rice and rapeseed and the total yields of the two seasons were increased by 8.6％-19.3％,19.1％-27.3％ and 10.3％-24.1％,and the net profit and cost were increased by 1651-4905 and 1427-2882 yuan/hm2.The highest contents of soil organic carbon components,nutrients and crop yields were observed in the SF3,however,there was no significant difference in the yields office and rapeseed between SF3 and SF2 with reducing the amount of fertilizer 255 kg/hm2.The relationships among the soil organic carbon components,nutrient contents and crop yields were significant or extremely significant.The stepwise regression analysis showed that soil total N,humic acid and water soluble organic carbon content were the key factors determining the yields of rice and rapeseed.Conclusions] NPK fertilizers plus straw returning are effective to increase soil total carbon accumulation and soil fertility,improve the crop yields.In spite of higher inputs in labor and fertilizers,the straw returning plus proper fertilizer application rate is still profitable in rice and rapeseed rotation system.