Research On The Effect Of Dicyandiamide Inhibits Nitrification And Degrades Mechanism

Nitrate of vegetables pollutes is closely related with nitrification, besides factors such as soil type, vegetables variety, etc. The fertilizer of soil influences the main external factor of content of nitrate in vegetables, choosing suitable nitrogen kind and amount and controlling to activity and quantity of ammonia oxidize the bacterium through the way that nitrification inhibitors to delay nitrification, it is the main technological measure that reduce the content of nitrate of vegetables. The test from the yield of vegetables, the nitrate content of vegetables, the type of nitrogen is transformed, ammonia oxidizes bacteria and dicyandiamide degrades fungus quantity, dicyandiamide content and pH to research nitrification inhibition and dicyandiamide degradation.The main conclusion is as follows:1 It shows that the Brassica chinensis with different dosage of nitrogenous fertilizers cultivated in a pot, the yield is treatment ABC> treatment Urea> treatment SN. The yield of water spinach of using the urea treatment is higher than using ammonium nitrate treatment, the yield of vegetable is the downward trend when being high nitrogen. The result of Different dosage nitrogenous fertilizers add dicyandiamide in the field test is that treatment ABC+DCD vegetable has the highest economic yield and biological output, it is the intersection of treatment SN+DCD secondly, and treatment Urea+DCD yield to be lowest, but it is not prominent to treatment SN+DCD.2 The result of different dosage of nitrogenous fertilizer effect on the mean value of nitrate content in vegetable is that treatment SN> treatment Urea> treatment ABC in the vegetable growing periods, the nitrate content of vegetable of ammonium treatment is higher than the urea treatment, and the nitrate content of water spinach increases as construct the increase of nitrogen quantity. Different dosage of nitrogenous fertilizers add DCD effect on the mean value of nitrate content in vegetable shows that treatment SN+DCD> treatment ABC+DCD> treatment Urea +DCD. At the harvest of vegetable of field trials, nitrogen content of nitrate attitude is treatment Urea+DCD>treatment ABC+DCD> treatment SN+DCD successively, and the nitrate content of vegetables revealed the same trend at harvest.3 During the entirely cultivated period of vegetable pot experiment, the nitrogen content mean value of ammonium attitude of soil is the treatment Urea> treatment ABC> treatment SN, the nitrogen content mean value of the nitrate attitude is opposite to it, and inorganic nitrogen mean value is treatment SN> treatment Urea> treatment ABC, and the dynamic change of ammonium attitude nitrogen and nitrate attitude nitrogen increases as construct the increase of nitrogen quantity in the soil, and add DCD treatment the content which has increased soil ammonium attitude nitrogen, especially construct the treatment of the urea. After using dicyandiamide amine in the field, the nitrogen content mean value of ammonium attitude of soil is successively treatment ABC+DCD> treatment Urea+DCD>treatment SN+DCD, but nitrogen content mean value and it is totally opposite in the soil nitrate attitude, the trend of tapering off of inorganic nitrogen in soil that inorganic nitrogen of treatment ABC+DCD and SN+DCD treatment, Urea+DCD treatment appear trend that reduce after rising.4 No matter urea or ammonium nitrate acid treatment, adding dicyandiamide lead to reducing the quantity that ammonia oxidizes the bacterium in the soil generally, Urea+DCD treatment reducing 31% and 25% than the corresponding one without adding DCD.5 The result from sterilized soil, regular soil and vegetables plant of study indicates that different dosage of nitrogenous fertilizer adds dicyandiamide degradation according with dynamics equation Ct=ae-bt in the soil, under the sterilized condition, the half-life of treatment Urea+DCD, ABC+DCD is 94.94d,135.76d, respectively; The soil cultivates under the condition conventionally, the half-life of treatment Urea +DCD, treatment ABC+DCD, treatment is 78.61d,96.32d, respectively; The vegetables are planted under the condition, and the half-life of treatment DCD, treatment Urea+DCD, treatment ABC+DCD, treatment SN+DCD is 21d-28d.6 The content of DCD really influences the quantity of cultured DCD degrading bacteria in the soil. The quantity of cultured DCD degrading bacteria in the soil culture experiment is 10 times tested for the field vegetables, and under the condition of planting vegetables in the field, the quantity of DCD degrading bacterium is nearly 10 times higher than DCD degrading fungi.7 A high level of dicyandiamide can influence sprouting and growth of vegetables. Testing this separately purified DCD, degrading the intersection of fungi use for the intersection of source and DCD degradable fungi, usually transforming with a pair of degradable dicyandiamide to the intersection of soil and nitrogen outside the research, the result indicates that DCD degradable fungi can make bone in sterilized and regular the intersection of soil that bank up with earth, sterilized DCD in soil bank up with earth, degrading the quantity of fungus higher than the regular soil extremely significant. Adding other intersection of source and DCD, degradeable fungi, can reduce the content of DCD in the soil.