落叶松凋落叶水提液对苗圃土壤微生物数量和土壤酶活性的影响

Effects of Water Extracts of Larix chinensis Litters on the Microbial Quantity and Enzyme Activity of Soil in Nursery

揭示落叶松凋落叶覆盖影响土壤理化性质的机理,为阐明落叶松凋落叶覆盖促进种子萌发和幼苗初期生长的机理提供科学依据。本文以不同浓度(0.2、2.0、20.0 g/L)长白落叶松凋落叶鲜提液或腐解液处理苗床表层土壤,测定处理前后土壤pH、土壤含水量、土壤养分(全氮、全碳、全磷、全钾、有效磷、碱解氮和速效钾)、微生物(细菌、真菌、放线菌)数量和土壤酶(水解酶类和氧化还原酶类)活性的变化。结果表明,不同浓度长白落叶松凋落叶的水提液(鲜提液或腐解液)处理均提高了土壤中全磷、全钾、速效钾和碱解氮的含量(P<0.05),其中,0.2 g/L鲜提液处理的碱解氮含量最高(比对照增加了75.13%)。水提液(鲜提液或腐解液)处理增加了微生物(真菌、细菌、放线菌)数量,促进了有机质的分解。与对照相比,腐解液对微生物数量的响应效应由大到小排序为:真菌、放线菌、细菌,其中2.0 g/L腐解液真菌增加率最高为526.90%,有机质分解速率增加了34.7%和36.83%。不同处理中,20 g/L鲜提液和腐解液的有机质分解速率最高。水提液(鲜提液或腐解液)处理提高了土壤中除碱性磷酸酶外的其他全部土壤酶的活性。酸性和氧化还原酶(过氧化氢酶、多酚氧化酶、过氧化物酶)均在水提液(鲜提液或腐解液)浓度为20 g/L时达到最高,而此时中性磷酸酶则最低。从而得到结论:落叶松凋落叶覆盖可增加土壤微生物的数量,且对真菌数量的增加最显著、落叶松凋落叶水提液可提高土壤酶活性、增加有机质分解速率、增强土壤中相关营养元素的转化效率。

This study reveals the mechanism of the effect of Larix chinensis litter cover on the physical and chemical properties of soil, and provides a scientific basis for clarifying the mechanism of litter cover promoting seed germination and seedling growth. Using different concentrations(0.2, 2.0, 20.0 g/L) of L. olgensis fresh extract or decomposed solution to treat seedbed surface soil, the changes of soil pH, soil moisture, soil nutrients(contents of total nitrogen, total carbon, total phosphorus, total potassium, available phosphorus, available nitrogen and available potassium), microbial(bacteria, fungi and actinomycetes) quantity and soil enzyme(hydrolases and oxidases) activity before and after treatment were measured. Results showed that: the contents of total P, total K, available K and alkali-hydrolyzed N in the soil were all increased by the treatment of water extract(fresh extract or decomposed solution) of different concentrations of L. olgensis litter(P<0.05). Among them, 0.2 g/L fresh extract had the highest alkali hydrolyzed nitrogen content(75.13% higher than the control). Water extract(fresh extract or rotten solution) treatment increased the number of microorganisms(fungi, bacteria, actinomycetes) and promoted the decomposition of organic matter. Compared with the control, the descending order of the response effect of the decomposition solution to the number of microorganisms was: fungi, actinomycetes and bacteria, and the highest increase rate of fungi in 2.0 g/L decomposition solution was 526.90%. The decomposition rate of organic matter increased by 34.7% and 36.83%. In different treatments, the decomposition rate of organic matter in 20 g/L fresh extract and decomposition solution was the highest. The activity of all the soil enzymes except alkaline phosphatase was increased by the treatment of water extract( fresh extract or rotten solution). Acid and oxidoreductase( catalase,polyphenol oxidase,peroxidase) were the highest when the concentration of water extract( fresh extract or decomposed solution) was 20 g/L,while neutral phosphatase was the lowest.The conclusion can be drawn: L. chinensis needle litters can increase the number of soil microorganisms and fungi,increase the activity of soil enzymes,increase the decomposition rate of organic carbon,and enhance the conversion efficiency of related nutrients in the soil.