不同用地土壤有机质和微生物对添加秸秆的响应

【摘要】选取采集于国内17个省(区)的不同利用方式下的85个土样为研究对象,定量添加玉米(Zea mays)秸秆置于相同温度培养90d,分析土壤有机质(soil organic matter,SOM)含量变化特征及其驱动因子。结果表明,添加玉米秸秆后,不同用地的SOM变化存在较大差异,63.5%的土壤样品的SOM增加,36.5%的减少;SOM含量相对变化率与其初始SOM含量呈显著负相关关系(P<0.05),说明在短期内添加秸秆并不一定意味着土壤有机质会提高。试验土样来源于4种不同用地方式中,采集于播种粮食旱地的88%的土样,其SOM含量增加;采集于水稻田的土样,其SOM含量均减少;采集于林地和菜地的土样,其SOM含量有增有减。添加秸秆后,各土样的可培养微生物数量均增加,增加量表现为水稻田>林地>菜地>粮食旱耕地,真菌>放线菌>细菌。磷脂脂肪酸(phospholipid fatty acid,PLFA)分析显示细菌/真菌与G+/G-均表现为水稻田>粮食旱耕地>林地>菜地,比值越小说明土壤生态系统越稳定;A/B和iso/anteiso、C/A均表现为菜地>粮食旱耕地>林地>水稻田,比值越小代表养分和环境胁迫越严重。因此,4种用地方式中,水稻田土壤生态系统稳定性较差,受养分和环境胁迫程度高。

【英文摘要】85 soil samples under different land use pattern were collected from 17 provinces in China.Then each soil sample was added with cornstalk and cultivated under natural condition for 90 d in order to understand the dynamics and motivation of soil organic matter (SOM) after the cornstalk addition.The results showed that the original land use pattern significantly affected SOM of soil samples with stalk.63.5 ％ soil samples had shown an increase of SOM,while SOM of 36.5％ soil samples decreased,which indicates that cornstalk addition did not necessarily lead to SOM increasing within a short period of time.SOM of 88 ％ soil samples from crop dry land had increased while it decreased all samples from paddy soils,and SOM in soils from forest lands and vegetable fields did not have obvious trend.After cornstalk addition,the number of cultivable bacteria,fungi and actinomycetes of all soil samples increased in the following orders:paddy field＞ forest＞ vegetable＞crop dry land,and fungi＞actinomycetes＞bacteria.According to phospholipid fatty acids (PLFA),the smaller bacteria/fungi and G+/G-,the more stable soil micro-ecosystem is;the smaller A/B,ios/anteiso and C/A are,the more unstabilitythe environment in soilis.PLFA analysis shows that soil micro-ecosystem stability increases in the following series:paddy field,crop dry land,forest land and vegetable land;the environmental and soil nutrient stress increases in the following series.vegetable land,crop dry land,forest land and paddy field.Therefore,paddy field had the worst soil micro-ecosystem stability and suffered the most nutrient and environment stress than all the other soils in this study.