长期种植大棚蔬菜对涂地土壤生物学性质的影响

Effects of Long-term Continuous Cropping of Vegetable in Polytunnel Greenhouse on Biochemical Properties of Coastal Soils

在浙东滨海平原选择连作时间为3～4年,8～10年和20年以上的大棚蔬菜地及蔬菜-水稻轮作8～10年和20年以上的大棚蔬菜地,同时选择刚围垦和经围垦改良脱盐的其他农地作为对照,分析研究不同种植年限和种植模式蔬菜地土壤微生物区系和酶活性,探讨长期种植蔬菜对涂地土壤生物学性质的影响。结果表明,围垦涂地种植蔬菜3～4年内,土壤有机质、氮和磷的全量和有效态、土壤微生物生物量碳、微生物数量、土壤酶活性均呈现增加的趋势,土壤质量明显改善;连作蔬菜8～10年后,土壤速效养分继续呈增加趋势,但土壤盐分显著积累,同时土壤生物学性质明显恶化(细菌和放线菌数量减少、真菌数量增加、土壤酶活性降低、土壤微生物生物量碳降低)。与连作相比,轮作可显著地防止土壤生物学性质的恶化。磷脂脂肪酸(PLFA)的方法研究也表明,蔬菜种植时间、种植方式(连作、轮作)对土壤生物学性质有很大的影响。

Vegetable lands in polytunnel greenhouse from coastal plain of eastern Zhejiang province with continuous cropping of 3-4 years,8-10 years,and more than 20 years,and rice-vegetable rotation cropping of 8-10 years and more than 20 years were selected for studying differences in soil microbial community and enzyme activities in vegetable lands with varying cultivation years and planting systems.Both newly-enclosed coastal land and reclaimed coastal land without vegetable cropping were also selected for comparison.The effects of long-term continuous cropping of vegetable on biochemical properties of coastal soils were discussed.The results showed that after 3-4 years of vegetable cropping,soil organic matter,total N,P,available N,P,microbiomass C,number of microorganisms,enzyme activities increased significantly,and soil quality was improved greatly.After continuous vegetable cropping of 8-10 years,soil available nutrients increased continuously,however,continuous accumulation of dissolved salt,decrease in numbers of bacteria and actinomyces,enzyme activities and microbial C,and increase in number of fungi indicated degradation of soil biochemical properties.Compared with continuous cropping of vegetable,rice-vegetable rotation was more beneficial for modifying soil biochemical properties.The results of phospholipid fatty acids of soil microbes also indicated that cultivation years and planting systems had a great influence on soil biochemical properties.