Studies On Micro-Algae's Ameliorative Effection To Sterile Soil

The paper fristly compared the fertile soil with the incinerated sterile soil on the number of micro-algae , soil pH value , soil organic matter soil available phosphorus and soil nitrogen.And then, the author put fertile soil, which included micro-algae, proportionally into sterile samples and cultivated them respectively under illumination condition (micro-algae can live and reproduce)and dark condition(micro-algae will die in some time).The above indices were measured in 0, 30, 60 and 90days respectively, The analyse of the interrelation between the change of micro-algae's number and the changes of soil pH value, soil organic matter, soil available phosphorus and soil nitrogen indicated:(l)Soil micro-algae which were native to fertile soil conld adapt to the changed circumstance and light acted as a decisive role to the distribution of soil micro-algae.Under dark condition,the micro-algae's number declined gradually and went to zero in the end,while under illumination condition ,on the 90th day, the micro-algae's number of per gramme was 6-7 times more than that of the beginning. (2)Through consuming CO2 and secreting alkaline matters from their cellls to soil, micro-algae can improve soil pH value,and transform the weak acid soil into weak base soil. (3) Through photosysthesis transforming CO2 into organic matters, micro-algae can increase the content of soil organic matter. On the 90th day, the content of organic matter of soil samples under illumination condition was 2-3 times more than that of the beginning.(4) Micro-algae can decompose organic phosphorus into inorganic phosphorus andincrease the content or the potential content of soil available phosphorus.(5)Theoretically, because of some micro-algae's nitrogen fixation,the sterile soil's content of nitrogen should increase, but in 90 days, its increment could not be determined. Perhaps,it is necessary for us to prolong experimental time and use more sensitive instrument in order to correctly evalunate soil micro-algae's effection to the increment of soil nitrogen.All in all, soil pH value ,soil organic matter, soil available phosphorus and soil nitrogen are important indices,which are used to measure soil's quality. The analyse of interrelation show: the increment of soil micro-algae has generous interrelation with the change of soil pH value, and has remarkable interrelation with the increments of soil organic matter and soil available phosphorus. This experiment tells us: soil micro-algae can ameliorate sterile soil. And this experiment's conclusions provide theoretical base for applying algae in the fields of agriculture , soil conservation and desert harness, and so on.