兰州新区不同土地利用类型对土壤有机质和养分及酶活性的影响

Effects of different land use types on soil organic matter and nutrients and soil enzyme activities in Lanzhou new district

研究了兰州新区3种不同土地利用类型(农耕地、城市绿地、未利用地)的土壤,测定了土壤脲酶、过氧化氢酶、蔗糖酶活性及土壤有机质和养分含量,分析了不同土地利用类型对土壤有机质和养分及酶活性的影响。土壤有机质和养分测定结果表明,农耕地表层土壤有机质、全氮和水解氮含量最高,与其相比城市绿地分别低14.7%、12.2%和13.0%,未利用地分别低57.7%、46.3%和26.2%,有机质、全氮及水解氮含量皆呈农耕地>城市绿地>未利用地的趋势;而城市绿地表层土壤有效磷和速效钾含量最高,与其相比农耕地分别低14.2%和18.4%,未利用地分别低84.7%和30.7%,有效磷和速效钾含量皆呈城市绿地>农耕地>未利用地的趋势。土壤酶活性测定结果表明,表层土壤中脲酶活性为农耕地(1.15 mg·g^-1)>城市绿地(0.82 mg·g^-1)>未利用地(0.35mg·g^-1);过氧化氢酶活性为农耕地(1.90 mL·g^-1)>城市绿地(1.62 mL·g^-1)>未利用地(0.79 mL·g^-1);蔗糖酶活性为农耕地(13.02 mg·g^-1)>城市绿地(11.64 mg·g^-1)>未利用地(8.61 mg·g^-1)。同一土壤深度垂直剖面的脲酶、过氧化氢酶及蔗糖酶活性皆呈农耕地>城市绿地>未利用地的趋势;上述3种土壤酶活性皆呈随土壤垂直剖面加深而降低的趋势,且0~20 cm层显著高于40~60 cm层。在兰州新区城市化进程中,土地利用类型的改变对土壤有机质和养分及酶活性有显著影响,并且影响基本上是有利的。

In this paper,the soils of three different land use types(farmland,urban green space,unused land)in Lanzhou new district are studied,the activities of soil urease,catalase,invertase and soil organic matter and nutrient contents are determined,also the effects of different land use types on soil organic matter and nutrient and enzyme activities are analyzed.The results of soil organic matter and nutrient determination show that the contents of organic matter,total nitrogen and hydrolyzed nitrogen in surface soil of farmland are the highest,compared with farmland the contents in urban green space are 14.7%,12.2%,13.0% lower respectively and the contents in unused land are 57.7%,46.3%,26.2% lower respectively.The contents of organic matter,total nitrogen and hydrolytic nitrogen all show the trend of farmland>urban green land>unused land.However,the contents of available phosphorus and available potassium in the topsoil of urban green space are the highest,compared with urban green space,the contents in farmland are 14.2%and 18.4%lower respectively,the contents in unused land are 84.7%and 30.7% lower respectively.The contents of available phosphorus and available potassium all show the trend:urban green space>farmland>unused land.The results of soil enzyme activity determination show that the activities of urease in surface soil are as follows:farmland(1.15 mg·g^-1)>urban green land(0.82 mg·g^-1)>unused land(0.35 mg·g^-1),the activities of catalase are as follows:farmland(1.90 mL·g^-1)>urban green land(1.62 mL·g^-1)>unused land(0.79 mL·g^-1),the activities of invertase are as follows:farmland(13.02 mg·g^-1)>urban green land(11.64 mg·g^-1)>unused land(8.61 mg·g^-1).The activities of urease,catalase and invertase in the same depth vertical soil profile show the trend of farmland>urban green land>unused land.The aforementioned three soil enzymes activities show a decreasing trend with the deepening of vertical soil profile,and the value of the 0~20 cm layer is significantly higher than 40~60 cm layer.In the urbanization process of Lanzhou new district,the change of land use type has significant effects on soil organic matter and nutrient and enzyme activity,and the effects are basically beneficial.