Effects Of Chemical Fertilizer Reduction And Slurry Substituted On Nitrogen And Phosphorus Balance In Protected Vegetable Fields

The application of chemical fertilizer in vegetable cultivation in China is large,but nitrogen and phosphorus recovery efficiency is low,and the excessive application of chemical fertilizer resulted in a large surplus of nitrogen and phosphorus in Chinese cabbage.With the rapid development of large-scale and intensive livestock and poultry breeding industry,a large number of breeding wastes rich in nitrogen,phosphorus and other nutrients have been produced.It is one of the effective ways for resource recycling to replace chemical fertilizer in farmland after treatment.Aiming at the problems of large amount of chemical fertilizer in Chinese cabbage but low utilization rate of nitrogen and phosphorus,indoor culture experiment and field in situ experiment were used to study the effects of slurry application on soil ammonia volatilization and the effects of chemical fertilizer reduction and slurry substituted on the yield of Chinese cabbage,nitrogen and phosphorus utilization,nitrogen and phosphorus balance and heavy metals.The conclusions are as follows:?1?The effect of nitrogen intake in slurry on soil ammonia volatilization was significantly higher than that of temperature and pH on soil ammonia volatilization.The effect of soil water content on soil ammonia volatilization was significantly lower than that of nitrogen application,temperature and pH,while the interaction between soil water content and slurry nitrogen intake,temperature and pH had a significant effect on soil ammonia volatilization.In the range of temperature 15?35 ^oC,soil water content 60%?80%,pH 6?8,nitrogen application 60?120 kg N·hm^-2,the ideal experimental conditions for reducing the soil ammonia volatilization are as follows:the nitrogen application amount is 75.58 kg N·hm^-2,the temperature is 15.48 ^oC,the pH is 6.22,and the water content is 60.63%of the field water holding capacity.Considering the actual conditions and the temperature of 25 ^oC,the application conditions of the fertilizer for reducing the soil ammonia volatilization are as follows,the application amount of the fertilizer is 64.98 kg N·hm^-2,the pH is 6.02,and the water content is 73.42%of the water holding capacity in the field.?2?Chemical fertilizer reduction increased the utilization rate of nitrogen and phosphorus,but had no significant effect on the yield of Chinese cabbage.Environmental fertilization can reduce nitrogen surplus by reducing nitrogen input,while pig slurry substituted can reduce nitrogen surplus by reducing nitrogen input and increasing uptake of nitrogen in Chinese cabbage.Considering the yield of Chinese cabbage,the absorption of nitrogen and phosphorus,nitrogen and phosphorus recovery efficiency and the balance of nitrogen and phosphorus,the chemical fertilizer reduction is an effective measure to reduce agricultural non-point source pollution in Danjiangkou area.?3?Pig farm slurry substituted significantly increased Chinese cabbage yield.The nitrogen and phosphorus uptake of Chinese cabbage increased with the increase of nitrogen and phosphorus in pig farm slurry,and nitrogen and phosphorus recovery efficiency decrease with the increase of nitrogen and phosphorus in pig farm slurry.From the point of nitrogen surplus,the nitrogen surplus is the lowest when the current season utilization rate of pig farm slurry substituted is 100%,which is significantly lower than that of 75%and 50%.Considering the yield of Chinese cabbage,the absorption of nitrogen and phosphorus in shoots of Chinese cabbage,the nitrogen and phosphorus recovery efficiency and the balance of nitrogen and phosphorus,pig farm slurry substituted can meet the needs of Chinese cabbage growth without increasing the risk of soil nitrogen and phosphorus leaching,which is a better model of slurry application.