典型农田土壤酶活性分布特征及影响因素分析

Distribution Characteristics and Influencing Factors of Enzyme Activities in Typical Farmland Soils

土壤酶是参与有机物分解和养分循环的关键成分,其活性可以用作衡量土壤健康的指标。了解土壤酶活性对农田利用方式的响应,对评价土壤健康状况、建立可持续耕作管理模式具有重要意义。为探究不同农田生产方式下农田土壤酶活性分布及主要环境影响因素,以果园、蔬菜大棚、水田3种农田利用方式为研究对象,采用野外监测和室内分析相结合的方法,探讨了农田土壤中过氧化氢酶活性(S-CAT)、脲酶活性(S-UE)、水解酶活性(FDA)、中性磷酸酶活性(S-NP)分布特征与生物和非生物因子间的响应关系。结果表明,农田土壤酶活性因耕作管理方式不同,存在较大差异(P<0.05)。土壤过氧化氢酶活性表现为蔬菜大棚<果园<水田,土壤脲酶活性表现为蔬菜大棚<水田<果园,水解酶活性在不同耕作管理方式下无显著差异(P>0.05),中性磷酸酶活性表现为水田<蔬菜大棚<果园。前3种土壤酶活性的变异系数大于16%,为中等变异,中性磷酸酶为强变异。冗余分析(RDA)表明,影响土壤酶活性的关键因子是土壤全钾TK(P=0.002)、水解性氮HN(P=0.002)、呼吸通量SR(P=0.002)、pH(P=0.008)、有效磷AP(P=0.016)、全氮TN(P=0.002)和阳离子交换量CEC(P=0.040)。在上海农田的主要耕作模式下,土壤养分、呼吸通量、pH和阳离子交换量是影响农田土壤酶活性的主要因素。因此,在对不同类型农田土壤进行土壤健康评价时,应合理选择针对性的酶活性指标。

Soil enzymes have been considered as key soil components involved in organic matter decomposition and nutrient cycling.Their activity level could be regarded as important soil health indicator.It is important to identify the response of enzyme activities to different agricultural practices in evaluation of soil health status and establishment of sustainable land management mechanisms.Therefore,this study investigated the soil enzymes of catalase activity(S-CAT),urease activity(S-UE),hydrolase activity(FDA),neutral phosphatase activity(S-NP)and key soil environment factors.Three types of farmlands in Shanghai,i.e.,orchard,plastic shed vegetable field and paddy field were chosen as case-study areas.This study conducted both on-site monitoring and lab analysis to explore the response relationships between the distribution characteristics of soil enzyme activities and the biotic/abiotic factors.Results showed that,soil enzyme activities differed significantly(P<0.05)among different farmland types.S-CAT increased following the order of plastic shed vegetable field<orchard<paddy field,S-UE following the order of plastic shed vegetable field<paddy field<orchard,FDA showed no significant difference(P>0.05),and S-NP following the order of paddy field<plastic shed vegetable field<orchard.The variation coefficient of the first three enzymes was greater than 16%as moderate variation,while S-NP had strong variation.Redundancy analysis(RDA)showed that,soil enzyme activities were influenced by soil total potassium(TK)(P=0.002),hydrolytic nitrogen(HN)(P=0.002),respiratory flux(SR)(P=0.002),pH(P=0.008),available phosphorus(AP)(P=0.016),total nitrogen(TN)(P=0.002),and cation exchange capacity(CEC)(P=0.040).Soil nutrients,SR,pH and CEC were the main factors affecting enzyme activities in farmland under general tillage patterns in Shanghai.Our results support the conclusion that when evaluating soil health of different farmland soil types,it is important to select the most appropriate enzyme activities as soil health indicators.