Comparation Of The Release Of Nitrogen From Organic-Inorganic Fertilizers And Chemical Slow-Release Fertilizers

The unreasonable application of inorganic nitrogen caused a series of problems such as the waste of nitrogen resources, the reduction of the soil fertility and the quality of vegetables. Chemical slow-release fertilizer can slow down the release rate of the nitrogen in the soil while it has more higher market price. Organic fertilizer has many advantages. So it is significant to study on the slow-release effect of the nitrogen from organic-inorganic fertilizers and chemical slow-release fertilizer.In this paper, the dissolution characteristics of different nitrogen fertilizers in the water were studied by the "immersed in water" method.The results showed that the initial nutrient release rates of urea and organic fertilizer in the water were100%and0.56%respectively.The average of the initial nutrient release rate of chemical slow-release nitrogen fertilizer in the water was16.02%.The nitrogen release characteristics of organic-inorganic fertilizer and chemical slow-release fertilizer were studid by the "soil column intermissive leaching "method, compared with the inorganic nitrogen fertilizer (urea).The results showed that the chemical slow-release fertilizer and organic-inorganic nitrogen fertilizer both had good slow-release effects on nitrogen.The result of the plate colony counting showed that the number of the total microbe,bacteria and fungi in the soil of the organic-inorganic fertilizer had obviously increased compared with the inorganic nitrogen. And the increase degree increased along with the increase of the proportion of organic fertilizer. The Shannon index and Evenness index of DGGE revealed that the organic-inorganic fertilizer can improve the diversity of bacteria in the soil.The impact of the organic-inorganic fertilizer and chemical slow-release fertilizer on the production, nitrate content, soluble sugar and Vc content of pakchoi and spinach was studied by the pot experiment. The results showed that the organic-inorganic fertilizer and chemical slow-release fertilizer both can increase the yields and Vc content of pakchoi and spinach and also can reduce their nitrate content compared with the inorganic nitrogen fertilizer.And the effect of organic-inorganic fertilizer was better than chemical slow-release nitrogen fertilizer. Compared with the control (no fertilizer), the soluble sugar content of pakchoi and spinach had no significant changes under all fertilization mode other than the organic fertilizer, while the organic fertilizer made the soluble sugar content of pakchoi and spinach significantly increase.After the pot experiment,the soil organic matter content declined under all fertilization mode other than the organic fertilizer.Compared with the control (no fertilizer) and the inorganic nitrogen fertilizer, the organic-inorganic fertilizer made the soil organic matter content significantly increase and the effect was better than the chemical slow-relaese fertilizer.