The Slow- Release Effect Of Dual Control Agent On Urea And Nitrogen Transformation In Soil

Nitrogen fertilizer plays an important role in agricultural production and is an important aspect of increasing crop yield. Large amounts of nitrogen fertilizer, however, were applied to agricultural soils and unreasonable management measures in the agricultural production process, nitrogen loss through the pathway of ammonia volatilization, nitrification and denitrification, nitrate leaching, run off. The efficiency of nitrogen fertilizer is very low. Therefore, questions related to how to reduce nitrogen loss, improve nitrogen using efficiency, and adapt to nitrogen release and fertilizer requirement of plant growing became the key points in the world economic and agricultural sustainable development. The study of application of urease inhibitor and nitrification inhibitor have some significance for further studies on control of biological N transformation processes in soil, reduce nitrogen loss, reduce the risk of environmental pollution. Urease inhibitors and nitrification inhibitors effect corresponding process of urea nitrogen transformation in the soil. At present, there are two urease inhibitors were studied. But research of urease inhibitors/nitrification inhibitor application more focus on the application effect. Aiming at different effect, inhibitor dosage ratio, change mechanism of inorganic nitrogen in the process of nitrogen transformation with different doses of urease inhibitors and nitrification inhibitors. The objectives of this study were to explore the different strength and the dose effect of double control agent with different doses of urease inhibitors and nitrification inhibitor and its change mechanism of inorganic nitrogen in the process of nitrogen transformation, and then select the optimum of combination with urease inhibitors and nitrification inhibitors, and provide the efficient management and utilization of nitrogen fertilizer in agricultural production. The main research results and conclusions are as follows.(1) Double control agent with application effect. urease inhibitor boric acid and nitrification inhibitor Dicyandiamide(DCD) combined application, under the high, medium and low nitrogen level, the inhibitory effect of the nitrogen transformation are synergistic effect, compared with single application of urease and nitrification inhibitors, more effective inhibition of urea hydrolysis and nitrification. ammonium nitrogen in the soil to maintain a higher level of higher levels, and significantly delayed the release of nitrate nitrogen, reduced the loss of the nitrate nitrogen leaching.(2) The dosage rule of double control agent with application of inhibitor. The inhibition effect of boric acid and cooperate with DCD increased with the increase of the dosage of DCD, but it was not the highest. When the amount of boric acid was 1.1%, the amount of NH4+-N in soil was decreased in the initial stage of the cultivation, and the time of effective nitrogen retention was significantly increased; And the inhibition of ammonium oxidation with the increase of DCD dosage, and the amount of the double control agent when DCD is higher, the effective inhibition of ammonium oxidation time is gradually extended, showing a strong regulatory effect.(3) The effect and interaction of nitrogen dual control and Transformation. Boric acid and DCD were used to carry out two-way control of nitrogen transformation, and the effect of boric acid on the process of the transformation of nitrogen in the initial stage was greater, and the effect of nitrification inhibitor DCD in the process of nitrogen transformation was great. The inhibitory effect of the two controls was significantly influenced by DCD dosage and soil urease. There was a significant negative correlation between soil inorganic nitrogen and urease, while soil total nitrogen and urease were significantly positive correlation. Soil inorganic nitrogen and total nitrogen were positively correlated with DCD, and the ammonia nitrogen and DCD showed a significantly positive correlation. The soil pH and had a significantly positive correlation with urease and DCD. There was no significant correlation between soil urease and DCD.(4) Optimal combination of different nitrogen levels. The optimal inhibition of different concentrations of urease inhibitors and different concentrations of nitrification inhibitors was different under different nitrogen levels. Under high nitrogen level, high acid and high DCD combined treatment(1.4%BG+13%DG) was more effective to inhibit the conversion of ammonium nitrogen to nitrate nitrogen, while the combination of medium boric acid and medium DCD(0.8%BG+8%DG and 1.1%BG+8%DG) was more effective in delaying the transformation of nitrogen. Under medium nitrogen level, the treatments of 1.4%BZ+13%DZ, 0.5%BZ+13%DZ, 8%DZ+1.1%BZ, 8%DZ+0.8%BZ were effective in keeping the soil nitrogen in soil. 1.4%BZ+13%DZ and 0.5%BZ+13%DZ inhibited the longest time. Under low nitrogen level, low acid and high DCD combined treatment(0.5%BD+13%DD) can inhibit the conversion of ammonium nitrogen to nitrate nitrogen in soil.(5) Empirical research technique effect. Through the pot experiment, the experiment of tomato as the test material was carried out. 1.1% boric acid and 8% of Dicyandiamide(DCD) with the application of double control agents in combination, to increase tomato yield and reduce the nitrate content of tomato and improve the quality of tomato.