Effects Of Nitrogen Fertilizer And DCD Application On Tomato Growth And Nitrogen Losses In Greenhouse

Aiming at the problems of resources waste and environmental pollution negativeeffects in greenhouse vegetable production systems were caused by excessive use ofnitrogen fertilizers, which could lead to low nitrogen use efficiency in vegetablesproduction and serious N nitrogen losses (NO3--N leaching, N2O emissions and NH3volatilization). The indoor and field experiments were carried out to study the effects ofnitrification inhibitor DCD in improving the nitrogen use efficiency and reducing nitrogenlosses, and then select the optimum dosages of DCD and nitrogen fertilizer, which wouldprovide theoretic basis and technical instructions for the energy saving and emissionreduction, and sustainable, healthy development of greenhouse vegetable production. Themain results are as follows:1. Use of nitrification inhibitors DCD can effectively restrain nitrification rate andreduce nitrogen losses in greenhouse soil. Nitrification inhibition effect of DCD wasstrongly influenced by DCD dosage and temperature. The time of DCD remaining wasonly5~7days under the30℃condition in the soil. The inbititor effect of DCD wasenhanced with the increase of the dosage. The nitrification inhibition effect was the bestwhen DCD was applied at15%of the N application rate.2. The application of DCD could significantly inhibit the conversion of NH4+-N toNO3--N, improving the nitrogen use efficiency, and reducing the accumulation andleaching of NO3--N in the soil under optimum water and nitrogen management condition.Compared with conventional fertilization treatment, optimize fertilization with DCD canimprove the nitrogen use efficiency in greenhouse tomato production from14.63%to29.37%. It can also reduce NO3--N content by63.70%~80.53%in the surface (0~30cm)soil and by64.63%~73.04%in the deep (30~120cm) soil.3. Under the condition of different application rate of DCD, the peaks of N2Oemission and soil NH3volatilization were on the1~3th days and the3days after thefertilizer and irrigation, respectively. Compared with the conventional fertilizationtreatment, the total N2O emissions in soil were reduced by25.53%~78.97%, and theamount of NH3volatilization were reduced by11.25%~38.64%. 4. The combination of DCD with conventional fertilization management couldimprove the quality of tomato, and the nitrate content in the tomato fruit can be reduced by51.94%~62.82%. The combination of DCD with optimal fertilization management couldreduce the nitrate content in tomato fruit by61.8%. In addition, the application of DCDcould also effectively guarantee the content of Vc, soluble sugar and soluble protein intomato fruit.5. The combination of the nitrogen rate of192kg·hm-2with DCD applied at10%ofnitrogen rate could not only improve the nitrogen use efficiency and reduce the nitrogenlosses but could also guarantee the yield and quality of tomato fruit, which was the suitablenitrogen and DCD management method in greenhouse tomato production and achievedboth economic and encvironmental benefits.