Study On The Effects And Evaluation Methods Of The Nitrogen Fertilizer Synergist

In order to prolong fertilizer effect period, improve nitrogen utilized efficiencyand protect ecological environment, the research of nitrogen fertilizer synergist is a hotspot all long. With the large-scale application of nitrogen fertilizer synergist, it is an urgent problem that reasonable assessment of nitrogen fertilizer synergist to be solved. This test was taken on alkaline soil to research the 6 fertilizer synergists effect results and evaluation method. The incubation method, pot experiment were carried out to study the single factor of various concentration of nitrification inhibitors DCD and DMP, urease inhibitor PPD and HQ, ammonia stabilizer humic acid (F) and chitosan (K) and the conspiracy effect of their combination with each other by the analysis of the effect of soil urea-N transformation and fertilizer-N utilized efficiency, study on the evaluation method of the fertilizer synergist. The main results are showed as follows:1. Different types of nitrogen fertilizer synergists can significantly influence the soil nitrogen transformation. The incubation experiment showed that: (1) the treatments that urea mixed with 1%-5% (adding synergist account ratio of urea nitrogen. the same below) DCD and 1% DMP all can significantly increase the ammonium nitrogen content 39.8%~206.4%, reduce the nitrate nitrogen content 3.4%~57.1%. (2) Urea mixed with 1%-5% HQ and 1% PPD both can inhabit hydrolysis of urea in the first seven days. In greenhouse culture test, the treatment of 5%HQ can inhabit hydrolysis of urea to 14 days; in constant temperature culture it can inhabit hydrolysis of urea to 21 days. In constant temperature culture only the treatment of 5%HQ can increase the ammonium nitrogen content 6.7%, 1%~5%HQ treatment reduce the nitrate nitrogen content 19.4%~36.9%.2. The constant temperature culture test showed that: the inhibitors treatments on the effect of nitrogen transformation is better than greenhouse culture experiment, can delay the conversion of ammonium and nitrate from 7 to 14 days, the whole change trend of total nitrogen content is consistent. Nitrification inhibitors delay the conversion of soil nitrogen about 7 days. Urease inhibitor treatments delay the soil nitrogen transformation 7 to 14 days. Soil ammonium, nitrate, nitrification and urease activity inhibition rate are correlated with the time and the same time nitrification inhibitory rate and urease activity inhibition rate are positively correlated to the inhibitor content..3. The four inhibitors with urea fertilizer synergist pot test can increase of soil ammonium nitrogen accumulation in different degree, and the range is 13.8%~269.1%. Single application of different inhibitor treatment can increase soil available nitrogen, a range of 5.6% to 28.5%, significantly reducing the loss of soil nitrogen, a decrease range of 20.5% ~ 53.9%.4. Stabilizer ammonia treatment and urea nitrogen were significantly different with nitrogen loss rate, while the nitrogen transformation and urea was not significant. N loss rate can reflect the effect of stabilizer ammonia, and nitrogen transformation does not apply to the evaluation of effect of stabilizer ammonia. Pot experiment showed that 5% K and 5% F treatments can reduce N loss rate 53.9% and 34.9% respectively. 5. The nitrogen fertilizer synergists combination test which chitosan, DCD and HQ was applying in four gradients showed that: the treatments adding chitosan can effectively enhance the effect of nitrification inhibitor DCD and HQ+DCD treatments, but with the combined application of urease inhibitors HQ reduces its effect. Under the experimental conditions, the treatment 14 (2.5% DCD +0.5% HQ +1% K) is the better nitrogen fertilizer synergist combination.6. The action effect of inhibitors can be evaluated by the action period and action intensity of inhibitors. (1) Before fertilizer nitrogen completely transformed into nitrate nitrogen, ammonium and nitrate nitrogen contents in the soil are correlative to time. By fitting the regression equation, we can estimate the action period of inhibitors. (2) And the nitrification inhibitory rate is correlative to the incubation time. The correlation Coefficient of the regression equation is significantly. when the nitrification inhibitory rate reduce to 0, we can estimate the action period of inhibitors; Because the same incubation time the nitrification inhibitory rate is positively correlated to the inhibitor content, it can reflect the action intensity of inhibitors. (3)The inhibition rate of soil urease activity can reflect the action intensity of urease inhibitors,we also can estimate the action period of inhibitors.