长期冬种绿肥改变红壤稻田土壤微生物生物量特性

LONG-TERM APPLICATION OF WINTER GREEN MANURES CHANGED THE SOIL MICROBIAL BIOMASS PROPERTIES IN RED PADDY SOIL

以进行了31年的双季稻-冬绿肥长期定位试验的红壤性水稻土为对象,研究了长期冬种绿肥条件下土壤微生物生物量特性的季节变化,为阐释冬绿肥措施在稻田生态系统土壤碳氮转化中的作用机制提供理论基础。试验包括双季稻-紫云英(RRV)、双季稻-冬油菜(RRP)、双季稻-黑麦草(RRG)及双季稻-冬闲(RRF)4个处理,在典型时期(绿肥盛花期、绿肥翻压后、早稻成熟期、晚稻收获后)采集土壤样品,分析土壤微生物生物量碳氮及微生物商等方面的变化。结果表明,3种冬绿肥均提高了土壤微生物生物量碳(SMBC)、微生物生物量氮(SMBN)和微生物商,在土壤性质相对稳定的晚稻收获后均显著高于对照处理,全年平均值也多显著高于对照处理。豆科绿肥紫云英对SMBC和SMBN的提高作用最显著,晚稻收获后相对冬闲分别提高了21.12%和98.45%,全年平均值分别提高了15.92%和36.49%。取样时期对SMBC、SMBN和微生物商有较大的影响,但变化趋势基本一致,即绿肥翻压前后无明显变化,早稻成熟期降至最低,至晚稻收获后再次上升。SMBC/SMBN比值在不同绿肥处理间差异不大,但有明显的季节变化,早稻成熟期较高而晚稻收获后降低。因此,南方稻田冬种绿肥后土壤微生物特性明显改善,冬种绿肥是提升稻田土壤肥力的高效措施。

system has been and rice yields, of green manure fluctuation of soi In South China, applicat proved and is to be a high effect very beneficial to lve of winter green manure crops into the double ri rotation pattern in improving soil environments, the sustainable agriculture. The effects of long-term ce cropping soil fertility application crops on soil microbial biomass carbon, soil microbial biomass nitrogen and the seasonal 1 microbial biomass properties in red paddy soil were still not clear enough. Based on a 31- year long-term field experiment on cultivation of double cropping rice and winter green manure in red paddy soil in South China, soil microbial bi^mass properties were investigated at different stages, aimed to provide a theor carbon rice-m fallow etical basis for deliborating mechanism and effects of winter green manure on transformation of soil and nitrogen in the paddy ecosystem. The long-term field experiment includes 4 treatments, i.e., rice- vetch （ RRV ） , rice-rice-winter rape （ RRP ） , rice-rice-ryegrass （ RRG ） and rice-rice-winter RF ） . Soil samples were collected at 4 different typical stages, i.e., flowering stage of winter green manure crop （ S1 ） , after the incorporation of green manure （S2 ） , mature stage of early rice （S3 ） , and after the harvest of late rice （ S4 ） , for analysis of soil microbial biomass carbon （ SMBC ） , soil microbial biomass nitrogen （SMBN） , soil microbial quotient and soil microbial biomass carbon to nitrogen ratio （ SMBC/SMBN ） . The results showed that the cultivation of green manure crops increased the contents of SMBC, SMBN and soil microbial quotient. Especially at the S4 stage, when soil properties were relatively stable, all the green manure treatments were significantly higher than those in the RRF treatment, and similar trends were observed for the annual mean values. The SMBC and SMBN were most influenced by the leguminous green manure milk vetch. Compared with the RRF treatment, they were increased by 21.12% and 98.45%, respectively, at the S4 stage, and by 15.92% and 3.49% for the annual mean values, respectively. The annual average values of soil microbial quotient in RRV, RRP, RRG were 3.61%, 3.66% and 3.61%, respectively, significantly higher than that in RRF treatment （ 3.13% ） . Although the SMBC, SMBN and soil microbial quotient were affected by sampling time profoundly, they all showed similar trends at all the 4 sampling stages, i.e., no significant differences between the stage of S1 and S2, down to the lowest level at the S3 stage, and up again at the S4 stage. The SMBC to SMBN ratio did not vary much among different treatments but fluctuated obviously with the sampling stages, i.e., highest at the S3 stage （when soil being flooded ） and lowest at the S4 stage （ when soil being non-flooded ） . It could be concluded that soil microbial properties were improved obviously after the long term cultivation of winter green manure crops in red paddy soil in South China, furtherly supporting that the cultivation of winter green manure crops is an effective way for soil fertilizing in red paddy fields.