Effects Of Long-term Fertilization And Management On Soil Enzyme Activity Of Lou Soil

The soil enzyme activity is an important indicator to soil fertility, and it is a key factorinfluencing organic matter and nutrient transformation. Fertilization and soil managementpractices can significantly affect soil enzyme activity level. This study investigated effects offertilization and management regimes on the dynamic changes of soil enzyme activities basedon the long-term experiments in Guanzhong Plain, Shanxi province, China.Treatments at thesite included application of recommended doses of nitrogen (N), nitrogen and phosphorus(NP), phosphorus and potassium (PK), nitrogen, phosphorus and potassium (NPK),wheat/maize straw (S) with NPK (SNPK), dairy manure (M) with NPK (M1NPK andM2NPK) and un-amended control (CK). Besides two management regimes, fallow andabandonment were also included. The main results were as follows:1.During the corn growing season soil enzyme activity changed significantly. The sucrase,urease and cellulose activities reached the maximum values at corn tasseling stage,. Whilephosphatase appeared to be the highest at corn jointing stage. The overall performance of soilenzyme activity under different fertilization regimes can be arranged in the following order:MNPK> SNPK> NPK, NP> N and CK. The soil microbiomass were also significantlyaffected by different fertilization, the overall performance of soil microbial carbon andnitrogen under different fertilization regimes can be arranged in the following order: MNPK>SNPK, NP, NPK> N,CK.2. Soil invertase, urease, dehydrogenase and alkaline phosphatase activity tended toincrease year by year under all treatments. Long-term different fertilization significantlyimpacted on the tested enzyme activities. Overall, soil enzyme activities were higher underthe fertilized treatments than the control. The treatments can be arranged in the followingorder: M2NPK>M1NPK>SNPK>NPK>NP>PK>N>CK. In addition, the positive correlationbetween soil enzyme activitiies and soil organic matter and nutrient level indicateimprovement of soil chemical, biological fertility on the tested soil.3. Different long-term soil management regimes had no significantly effect on alkalinephosphatase activity between seasons. However, invertase and urease activity showed asignificant seasonal dynamics with the ambient temperature, moisture and plant growth development. Overall, the enzyme activity in the corn growing season was higher than that inthe wheat growing season. In terms of the average of three enzyme activities in differentseasons, invertase and urease activities were: cropping system> setaside> fallow and alkalinephosphatase activity was: crop system> setaside> fallow. In addition, the results of soilenzyme activities in the annual dynamic changes showed that soil dehydrogenase, invertaseand urease activities increased year by year under different long-term management regimes.However, long-term fallow and set aside had no significant effect on alkaline phosphataseactivity over years (except crop system).In conclusion, soil enzyme activities displayed the increasing trend with fertilizationhistory under winter wheat rotated with summer maize cropping system. Application ofchemical N and P can improve soil chemical and biochemical fertility, the crop straw plusNPK was better than the NPK treatment, and the treatment with organic and inorganicfertilizer was the best fertilization pattern to improve chemical and biochemical fertility. Thelong-term bare fallow cannot keep the level of soil enzyme activity, and the long-term cropland abandonment was benefit to improve the soil enzyme activity, furthermore, its soilenzyme activities was similar to or higher than the cropping system after15years.