Dynamic Change Of Soil Enzyme Activity In Pond Sediments Derived From Three Different Purple Parent Soils

Bottom soil can be a sink or a source of dissolved substances for fisheries water. Research and practical observations clearly reveal that pond soils influence water quality and production. In extensive aquaculture production, yields are better in areas where soils are fertile than in places where soils are infertile. It shows that the soil conditions, to a certain extent, restricts the pond primary productivity, and also restricts the pond fishery force. The soil fertility assessment is a most important part of soil research, while the soil enzyme activity studying is the main means and indicator about it. Soil enzymes plays an important role in the C, N, P, S or other substances and the energy cycles, is an important part of the material exchange in pond sediment, as the engine of the soil metabolism. To carry out the appropriate soil fishery evaluation work by in combination of the primary productivity of the water, soil fertility and soil enzyme activities, can make a contribution to the promotion and development of freshwater fisheries.In order to research the enzymes activity about the purple soil sediment, we carried out the experiment to study the influence of soil nutrients and feed deposition to the sediment enzymes activity, used three different types of purple parent material soil:Penglaizhen (S1), Shaximiao (S2), the Suining group (S3).Firstly, we analyzed the nutrition properties of soil and determined the soli enzymes activity to find out the correlation between soil enzyme activity and soil nutrient; Then, we took an indoor static experiment under lighting to study characteristics of the enzymes activity change by three kinds of parent material purple soil in water environment, and to analyze the relationship about the sediment and the enzyme activity; Next, we designed the experiment to research the difference about sediment enzyme activity with the feed deposition by added exogenous nutrients under the same conditions; Finally, we set a different level of feed adding in order to make a validation about the effect of feed deposition to sediment enzyme activity. The study results were as follows:1.The result of the first experiment about soil nutrient and enzyme activity showed that: (1) The major nutrients and trace nutrients of three types purple soil were S1>S3> S2;(2) Due to the different type of soil, the enzyme activity changes:Hydrogen peroxide activity were S2> S1> S3;Alkaline phosphatase activity were S1> S2> S3; For sucrase activity, S2was the maximum, respectively2and4times about S1and S3.(3) Catalase activity was significantly positively correlated with available phosphorus content; Alkaline phosphatase was positively correlated with the total phosphorus content; Sucrase was significant positively correlated with alkaline hydrolysis nitrogen content and total phosphorus content, significant negatively correlated with pH and total nitrogen content.2. The results of the experiment about sediment enzymes activity showed that:(1) the enzymes activity of pond sediments which derived from three different purple parent soil there were differences, the hydrogen peroxide activity was S2> S1>S3; alkaline phosphatase activity were S1> S2> S3; protease activity was S2> S3> S1; urease activity was S2> S1> S3at pre-days, and was no significant difference after30days; the sucrase activity, while, there was no significant difference.(2) the trend of enzyme activity change about three groups was also different after flooding15d, alkaline phosphatase, rendering the "M" type cycle fluctuations, urease and catalase performance was gradually reduced and then the steady state, the enzyme of protease and sucrose was manifested in the process first and then decreased.3. Feed deposition experiment showed that:soil enzymes activity of pond sediments will be restrained at first by the feed deposition, and then increased generally. The total amount of the five enzymes(catalase, alkaline phosphatase, urease, protease, sucrase) activity was S1> S2>S3.4. From the study of sediment enzyme activity with different level about feed deposition,we can see that(1)An increase in the amount of feed deposition would makes the activity increased, and would lead to the slower growth or even temporary inhibition if too much;(2) The fluorescein diacetate (FDA) hydrolase activity can comprehensively reflect changes in the amount of enzyme activity in sediment. An increase in the amount of feed deposition will cause microorganisms activity in the sediment substantial increase, and the FDA hydrolase activity will be increased too.5. Conclusion:(1) Between different soils, the nutrient condition and enzyme activity was different;(2)The variation characteristic of the soil enzyme activity in different sediment was different;(3)The sediment enzyme activity would changed by the feed deposition, and a certain amount of feed deposited would cause the sediment enzyme activity increased.