不同扰动方式下加拿大一枝黄花对农业生产区土壤环境的影响

Influence of Solidago canadensis L.on Soil Environment in Agricultural Production Area Under Different Disturbance Modes

采用野外调查与样品分析法,探究了长沙县加拿大一枝黄花成片发生区、加拿大一枝黄花未入侵的水稻田(CK)、加拿大一枝黄花散生的灌木林地、化学防除加拿大一枝黄花后的试验田和加拿大一枝黄花发生区翻耕地5个样地在4种扰动方式(抛荒耕地、灌木林地、化学试验田、翻耕地)下加拿大一枝黄花对0~20 cm耕作层土壤的理化性质、主要微生物、养分和重金属含量的影响。结果表明:与CK相比,加拿大一枝黄花成片发生地土壤pH值明显偏低,而化学防除后的试验田土壤pH值最高。样地中加拿大一枝黄花成片发生区土壤含水率和有机质含量均最高,分别达36.34%和9.49%。5个样地中土壤微生物数量存在显著差异,加拿大一枝黄花入侵样地中土壤细菌数均高于CK,灌木林地和化学试验田土壤真菌数较高,均达到了6×10^6 CFU/g以上,而加拿大一枝黄花成片发生区土壤真菌数最低,仅为2.60×10^6 CFU/g;5个样地中土壤放线菌数也存在差异。加拿大一枝黄花的入侵可以提高土壤养分含量,增加土壤肥力,且与入侵程度密切相关。加拿大一枝黄花生长密度越大,土壤全N、全P、速效K含量越高,分别为CK土壤的1.86倍、1.08倍、1.33倍。5个样地中,加拿大一枝黄花成片发生区土壤中Pb、Ni、Cu、Cd、Cr、Zn含量均为最高,土壤综合污染指数(Pzong)也最高。从污染程度上看,5个样地土壤中8种重金属元素单因子污染指数均低于1,均为无污染等级;综合污染指数(Pzong)为0.38~0.50,均为安全等级。说明不同扰动方式下加拿大一枝黄花对农业生产区土壤的理化性质、微生物量、养分和重金属含量的影响均存在明显差异。

Influence of Solidago canadensis L.on the physi-chemical properties of soil,main microorganisms,soil nutrients and heavy metal contents in 0-20 cm cultivated layer were studied by field investigation and sample analysis.Soil samples were collected under four disturbing modes(abandonment of cultivation,shrubbery,chemical control,ploughing)from 5 plots,i.e.Solidago canadensis L.massively invaded region,paddy field(CK),shrubbery,chemical treated field after Solidago canadensis L.invasion and tillage soil of invaded region in Changsha County.The results showed that compared with paddy soil,the pH of Solidago canadensis L.massively invaded soil was significantly lower,whereas that of chemical treated field was the highest.The contents of soil moisture and organic matter of the massively invaded soil were the highest among the samples,reaching 36.34%and 9.49%,respectively.Significant difference of microbial populations was observed.The numbers of bacteria in all the invaded soils were higher than in the paddy soil;the numbers of fungi in shrubbery and chemical treated soils were higher,reaching 6×10^6 CFU/g,however,the number of fungi in the massively invaded soil was the lowest,only 2.60×10^6 CFU/g.Numbers of Actinomycetes were also varied with different disturbing modes.The invasion of Solidago canadensis L.can increase nutrient contents and fertility of the invaded soil,which is closely related to the levels of invasion.The greater the growth density of Solidago canadensis L.,the higher the contents of total N,P and K in the massively invaded soil,which were 1.86,1.08 and 1.33 times of those in CK soil respectively.The contents of Pb,Ni,Cu,Cd,Cr and Zn in the Solidago canadensis L.massively invaded soil were the highest among five sampling plots,so was the soil comprehensive pollution index(Pzong).Single factor pollution indexes of 8 heavy metals in the five sampling plots were all lower than 1.0,belonging to non-pollution level;while their Pzong values were in the range of 0.38-0.50,belonging to security level.The results of this study showed that there were significant differences in the effects of Solidago canadensis L.on soil physi-chemical properties,soil microorganisms,soil nutrients and heavy metal contents under different disturbing modes in agricultural production areas.