土壤次生盐渍化与微生物数量及土壤理化性质研究

次生盐渍化已成为制约设施栽培农业发展的主要障碍因子,为揭示次生盐渍化对土壤微生物和理化性质的影响,对上海市南汇区和崇明区设施栽培大棚土壤酶活性和微生物活性进行研究.结果表明:随着栽培时间的增加,土壤表层(0-5 cm)有机质变化不明显;而土壤中硝态氮和总盐量增加,连续栽培15年土壤的硝态氮(94.23 mg/kg)是露地表层土的14.8倍,EC值是露地的14.9倍;从第5年起土壤出现酸化现象.次生盐渍化越严重,对土壤脲酶、磷酸酶和呼吸强度的抑制越明显,连续栽培15年土壤脲酶活性受抑制率达到71.8%.EC值、总盐、硝态氮与放线菌、细菌数量都呈极显著负相关,与真菌数量呈显著负相关,最高相关系数达到-0.957.次生盐渍化对于深层土(15-20 cm)的影响没有表层土明显.

Secondary Salinization of Greenhouse Soil and Its Effects on Microbe Number and Soil Physico-Chemical Properties

Secondary salinization has become a major obstruction factor to development of cultivated agriculture.To reveal the impact of the secondary salinization on soil microbe distribution and physico-chemical properties,the soil enzyme activities and microbial activities were investigated in greenhouse soil of Nanhui and Chongming district in Shanghai,The results indicated that:with the increase of facility cultivation time,organic matter of top soil(0-5 cm)did not change obviously but soil nitrate and total salt were gradually accumulating with the time.The amount of nitrate in 15-year land with 94.23 mg/kg was 14.8 times than that in 0-year,and the electric conductivity(EC)was similar.A lower PH were measured after 5-year facility culturing activity.The more serious of soil secondary salinization.the more significant of inhibition of soil enzyme and soil respiration.Inhibition rate of urease activity in 15-year land reached 71.8%than that in 0-year.EC,the total salt and nitrate had highly significant negative correlation with number of actinomycetes and bacteria,had significant negative correlation with number of fungi.The highest correlation coefficient reached-0.957.Secondary salinization effects on deep soil(15-20cm)was not as significant as top.