施氮、磷肥对秦岭北麓华北落叶松人工林地土壤生物学特性影响

Effects of nitrogen and phosphorus fertilization on soil enzymatic activities and microorganism in Larix principis-rupprechtii plantation

为了研究施肥对秦岭北麓地力衰退的中龄林华北落叶松人工林地的土壤生物学特性影响,评价施肥对缓解地力衰退的作用。在陕西省太白县南滩苗圃选取20年的华北落叶松人工林地,并对其进行施肥处理,通过野外采样和室内分析相结合的方法,研究了施肥对华北落叶松人工林地土壤酶(蔗糖酶、脲酶、磷酸酶、过氧化氢酶)活性和土壤微生物数量的影响。结果表明:不同施肥处理均不同程度地提高了土壤过氧化氢酶活性、磷酸酶活性、脲酶活性和蔗糖酶活性;其中在5和7月,氮磷配施处理对酶活性的影响最大。施肥处理对酶活性的影响9月不及5和7月显著。不同的施肥处理提高了华北落叶松林地土壤放线菌数量,氮磷配施效果最明显,单施氮肥降低了细菌的数量,施氮肥75 kg/hm^(2)和磷肥75 kg/hm^(2)处理降低了土壤真菌的数量。土壤酶活性和土壤微生物数量都随着月份推进呈先升高后降低的趋势。研究表明,施肥处理对秦岭北麓中龄林华北落叶松人工林地的生物学特征有一定的改善作用,可以有效缓解20年华北落叶松人工林地的衰退问题。

In order to study the effect and function of fertilization on soil biological characteristics in Larix principis-rupprechtii plantations,we chose 20 years old Larix principis-rupprechtii plantation in the Nantan nursery garden of Taibai county in Shaanxi province as the experimental sites,and set up different fertilization treatments,and studied the effect of different fertilization treatments on soil enzyme activity(sucrase,urease,phosphatase,catalase)and number of microorganisms(bacteria,fungi,actinomyces)by combining field sampling and indoor analysis.The result showed that all fertilization treatments enhanced soil activities of catalase,phosphatase,urease and sucrase.Nitrogen and phosphorus combined treatment had the greatest effect on enzyme activity in May and July.All fertilization treatments enhanced soil actinomycetes number,nitrogen and phosphorus combined application had the most obvious effect.Applying only nitrogen reduced the number of bacteria,and 75 kg/hm^(2)nitrogen and 75 kg/hm^(2)phosphorus treatment reduced the number of soil fungi.Soil enzyme activity and soil microbial quantity increased first and then decreased with the promotion of month.The result of this study showed that applying fertilizer could improve soil biological characteristics and effectively alleviate the fertility decline of 20 years old Larix principis-rupprechtii plantation.