Effects Of Different Purple Parent Soil Extracts On The Growth Of Algae

The nutrients from sediment mineralization determine the primary productivity and the fishery productivity of the pond. So it is very important to survey the contribution of soils to the material cycle and energy flow in the water. In this study, three purple parent soils were used to investigate the effects of different parent soils on the growth of phytoplankton. First, the nutrients of the soils and their extracts were detected by soil agricultural chemistry analysis. And then, the germination characteristics of in situ algae in different parent soil extracts were observed. Finally, Scenedesmus quadricanda,Chlorella vulgaris and Nitzschia sp., which are preferable food for fish, were cultured in the three parent soil extracts by indoor illumination. The results were as follows:(1)The value of pH, the content of organic matter, effective phosphorus, effective sulfur, Mg and Cu were significant different among the three purple parent soils. The content of effective phosphorus, effective potassium, effective nitrogen, effective sulfur, TN, Ca and Zn content among tested soils was S1>S3>S2, but the content of Fe and Mn was S3>S2>S1. The content of Cu was S1>S2>S3, and the content of Mg was the biggest in S2.(2) The difference of dissolution rate for TN, TP, TK and Ca were significant among the three purple parent soils. For most of the nutrients, a positive correlation of dissolution rate between soil and soil extract was showed.(3)The nutrient content in soil extracts changed with extraction time. The concentration of Ca increased with the extraction time, and the other nutrients showed alternately feature. In the whole process, pH, the content of K and Ca in SE1were the highest, but that of Mg and S were the lowest; Ca in SE2was the highest; B in SE3was the highest.(4) The distribution of phytoplankton was different in different soils. The number of species of algae in S1was48, and then S3was37, and the least was S2which was only24. The Shannon’s diversity index of the algae was separately1.507,1.188and1.219, and the Simpson’s diversity index was separately0.707,0.627and0.638.Bacillariophyta, Cyanophyta, Euglenophyta, Chlorophyta and Cryptophyta were found in all kinds of soils. The maximum quantity was Chlorophyta, and the second was Cyanophyta. There were no Xanthophyta and Chrysophyceae in S2, and no Xanthophyta in S3. The number of species and density were correlated with soil nutrients.(5)Scenedesmus quadricanda grew well in soil extracts. The maximum density of Scenedesmus quadricanda appeared at the eighth week, and the order was SE3>SE2>SE1.The maximum density of SE3was22×104ind./ml, which was1.63times of SE1and1.50times of SE2.(6) The order of maximum density of chlorella vulgaris in different soil extracts was SE1>SE2>SE3. The tenth day, the density of algae was25×105ind./ml in the control group, which was2.74times of SE1,2.64times of SE2and3.04times of SE3.(7) Nitzschia sp. grew badly in the soil extracts, and the maximum density of Nitzschia sp.in soil extracts was SE1>SE2>SE3.(8)The experiment showed that algae density and growth rate were correlated with the nutrients of the purple soil extracts.