Comparative on technical measures for controlling nitrogen loss from tomato soil in greenhouse facilities

As the largest vegetable variety in China, tomato has serious soil nitrogen loss caused by the large amount of nitrogen fertilizer and irrigation, which aggravates the nitrate pollution of groundwater. In order to effectively reduce the soil nitrogen loss caused by unreasonable nitrogen application and irrigation in the production process of facility tomato, this study integrated the physical barrier materials, fertilizer synergists, enzyme preparations, microbial preparations and other products and application technologies developed by the national key research and development plan project "Nitrogen and phosphorus pollution load reduction technology and product development in facility Agriculture". The control technology of soil nitrogen loss in facility tomato was developed in order to provide reference for soil nitrogen loss control in facility vegetable field. This study set up conventional fertilization (FP), optimal fertilization (OPT), physicochemical regulation (PCT), biological ecological regulation (BET), water and fertilizer regulation (WRT) and comprehensive regulation (CRT) through the application of physical barrier materials, fertilizer enhancer, enzyme preparations, microbial preparations and other products that can prevent and control soil nitrogen loss. Tomato yield, soil nitrogen loss and its form were measured under different measures. Economic benefit of tomato was measured under different measures. The experiment compared and screened the best soil nitrogen loss control technology. The results showed as follows: the yield of tomatoes treated with OPT and FP was the same, and the yield of tomatoes treated with CRT was the highest, which was significantly higher than that treated with FP, OPT and BET (P<0.05). The yield of tomatoes treated with PCT, BET, WRT and CRT was 4.70%, 2.05%, 7.93% and 9.28% higher than that treated with FP, respectively. The total yield of CRT treatment was the highest, followed by WRT treatment, PCT treatment and BET treatment, and FP treatment had the lowest yield. WRT had the highest net return, 8.73% higher than FP treatment, and PCT treatment had the lowest net return. FP treatment had the highest total nitrogen content (114.8 kg∙hm⁻²), which was 25.6%, 35.6%, 34.5%, 40.5% and 40.9% higher than OPT treatment, PCT treatment, BET treatment, WRT treatment and CRT treatment, respectively. The nitrate nitrogen loss of FP treatment was the highest (49.0 kg∙hm⁻²), which was significantly higher than that of other treatments (31.5%~49.2%), and that of CRT treatment was the lowest. The organic nitrogen loss of FP treatment was the highest (65.8 kg∙hm⁻²), which was 21.2%, 37.7%, 31.5%, 38.0% and 34.7% higher than that of OPT treatment, PCT treatment, BET treatment, WRT treatment and CRT treatment. Organic nitrogen and nitrate nitrogen accounted for 55.2%-62.9% and 36.7%-44.6% of total nitrogen in different treatments, and ammonium nitrogen accounted for less than 0.5%. The nitrate nitrogen content in 0-100 cm soil layer treated by FP was lower than that treated by OPT, the ammonium nitrogen content was lower than that treated by WRT and CRT, and the nitrate nitrogen content in 20-100 cm soil was displayed as WRT >CRT >BET >PCT. In this study, combining economic and environmental benefits, water and fertilizer regulation can be used as the best technology to control soil nitrogen loss in tomato plants.