长期稻-稻-油菜轮作对土壤理化性质及微生物群落结构的影响

为探究南方丘陵地区稻-稻-油菜轮作对土壤理化性质和微生物群落结构的影响,采用常规土壤农化分析和磷脂脂肪酸(PLFA)分析方法,以安仁县长期稻-稻-油菜轮作(DDY)和稻-稻连作(DD)土壤为研究对象,比较长期(30 a)DDY和DD处理后3个时期(早稻成熟期、晚稻成熟期、油菜成熟期)土壤理化性质和微生物群落结构的差异。结果表明,DDY处理土壤全氮、全磷含量及pH值均低于DD处理,其中,全氮含量在3个时期均差异显著,全钾含量增加但与DD处理差异不显著,有机质、碱解氮、速效磷、速效钾含量呈动态变化。轮作对土壤全氮含量影响较大,3个时期DDY处理全氮含量分别较DD处理降低50.76%、46.67%、49.62%。土壤微生物PLFA分析结果表明,与DD处理相比,DDY处理土壤微生物PLFA总量显著提高,3个时期分别提高19.69%、20.20%、49.12%,其中,DDY处理土壤细菌PLFA量显著增加,真菌PLFA量显著降低,真菌与细菌PLFA量比值显著降低。对土壤微生物PLFA进行主成分分析表明,轮作对微生物群落结构产生明显影响,2种种植方式主要影响土壤中细菌和真菌的数量。总之,长期稻-稻-油菜轮作促进了土壤全氮和全磷的分解,显著提高微生物生物量,尤其是细菌生物量,显著降低真菌生物量,提高两者的比值。

Effects of Long Term Rice-rice-rape Rotation on Soil Physicochemical Properties and Microbial Community Structure

To explore the effect of rice-rice-rape rotation on soil physicochemical properties and microbial community structure in hilly area of southern China,the soil microbial biomass and composition of two kinds of different tillage systemslong rice-rice-rape rotation(DDY) and rice-rice continuous cropping(DD)] after 30 years of rotation were analyzed by PLFA marker spectrum analysis method,and the soil physicochemical properties during three periods(including the mature stages of early rice,late rice and oilseed rape) were studied.The results showed that compared with DD treatment,the contents of total N and total P and pH value of DDY treatment decreased,there was a significant defference for total N content,the total N content of DDY treatment significantly decreased by 50.76%,46.67%,49.62%;the total K content of DDY treatment increased,but the difference was not significant;the contents of organic matter,alkali-hydrolyzable N,available P,available K showed dynamic changes.Soil microbial PLFA marker test showed that compared with DD treatment,soil microbial PLFA amount of DDY treatment increased by 19.69%,20.20% and 49.12% at three different determination stages,respectively;the bacterial PLFA amount of DDY treatment increased,the fungi PLFA amount of DDY treatment decreased,and the ratio of fungi PLFA amount to bacteria PLFA amount of DDY treatment decreased.The principal component analysis of microbial PLFA showed that rotation obviously influenced the microbial community structure,the amount of bacteria and fungi were mainly affected by two tillage methods.Overall,the long term rice-rice-rape rotation promoted the decomposition of total N and P,significantly improved the microbial biomass,especialy bacteria,significantly decreased the fungal biomass,significantly increased the ratio of bacteria to fungi.