土壤理化性质和微生物活性对水田改果园的动态响应

Response of Soil Physicochemical Properties and Microbial Activity on Land-use Conversion from Paddy Field to Orchard Farm

[目的]探讨土壤微生物特性及环境因子对水田改果园的动态响应规律,为进一步研究土地利用变化对土壤生态环境的影响,预测水田改果园后土壤质量的长期变化趋势提供科学依据。[方法]在浙江省范围内选择1个代表性的水田改果园土壤系列,采用后切时间序列法,分析水田改果园后土壤理化性质、土壤微生物生物量及酶活性等指标的动态响应规律。[结果]水田改果园后,土壤含水率、>0.25 mm水稳定性团聚体、pH值、有机质、盐基饱和度、全氮、碱解氮含量显著(p<0.01)下降,全钾、有效钾、全磷和有效磷含量分别增加了21.9%,54.7%,42.0%和6.65倍,并且这些指标都与植树年限呈极显著(p<0.01)相关。改果园后,土壤微生物生物量碳和氮平均含量分别下降了74.4%和73.3%,土壤脲酶和酸性磷酸酶活性平均值分别增加了40.0%和41.8%,土壤过氧化氢酶活性平均值下降69.3%,并都与植树年限呈极显著相关(p<0.01)。[结论]水田改果园后土壤环境因子发生阶段性变化,且土地利用方式的影响要大于利用年限的影响。水田改果园后土壤综合肥力下降,并对生态环境和土地可持续利用带来不利影响。

[Objective]The dynamic response of soil microbial characteristics and environmental factors to the change of paddy fields into orchards was discussed in order to provide a scientific basis for further study of the impact of land use change on soil ecological environment and prediction of the long-term change trend of soil quality after the change of paddy fields to orchards.[Methods]One representative soil series of land-use change from paddy to orchard were chosen in Zhejiang Province,furthermore,the law of dynamic response of soil physicochemical properties,enzyme activity and soil microbial biomass to land-use change was analyzed using the post-cut time series method.[Results]Soil moisture,>0.25 mm water stable aggregate,pH value,organic matter,base saturation,total nitrogen and alkali-hydrolyzable nitrogen fell down significantly(p<0.01),however,total phosphorus,available phosphorus and available potassium increased by 21.9%,54.7%,42.0%and 6.65 times,respectively,and these indexes were correlated with years of planting trees significantly(p<0.01).After the land-use change,the average of soil microbial biomass carbon and nitrogen decreased by 74.4%and 73.3%,respectively.The average of soil urease and acid phosphatase activity increased by 40.0%and 41.8%,respectively.However,the mean value of soil catalase activity decreased by 69.3%,and they were significantly(p<0.01)correlated with the time of planting trees.[Conclusion]After the land-use conversion from the paddy field to orchard farm,soil environmental factors changed periodically,and the influence of land-use pattern was greater than that of land-use history.Moreover,soil comprehensive fertility decreased,and the ecological environment and sustainability of land use were adversely affected.