Nitrogen And Phosphorus Accumulation And Leaching Effects In Vegetable Soils Under Different Fertilization Measures

Soil nitrogen(N)and phosphorus(P)leaching has been the main pathway of reactive nitrogen and phosphorus loss,which were caused by the accumulation of soil nitrate and phosphorus in vegetable soils.However,it is still unclear on the systemic effects of different nutrient managements on soil nitrate and phosphorus accumulation and leaching in vegetable fields.In this study,a Meta-analysis was used to clarify the effects of reduced nitrogen application(RF),combined application of organic and inorganic fertilizers(OF)and inhibitor regulation(IFN)on the accumulation and leaching of nitrate and phosphorus in vegetable soil,taking the conventional nitrogen application(TF),single fertilizer application(CF)and no inhibitor application(WIN)as control,respectively.And,the results of the Meta-analysis were further validated by soil column leaching simulations.The main findings are as follows:(1)The results showed that the three nutrient managements were effectively reduced the nitrate accumulation and leaching in 0-100 cm soil layer compared with the control.Specifically,the content of nitrate accumulation was significantly decreased in 0-100 cm soil layer in RFN,0-80 cm soil layer in OFN and IFN,respectively,compared with the conventional TFN,CFN and WIN.The average percentage reduction of nitrate leaching in RFN treatment was 48.72%,and was decreased with N reduction ratio increased.The average percentage reduction of nitrate leaching in OFN treatment was 34.32%.However,the inhibiting effect decreased significantly when the substitution rate of organic nitrogen fertilizer was more than 60%.The significant inhibiting effect on nitrate leaching was also found in IFN treatment compared with WIN,especially,the combination of urease and nitrification inhibitor could decrease nitrate leaching by 37.67%.Data analysis results showed that the nitrogen application rate and water input were the main influencing factors on nitrate leaching,and the total contribution rates reached by 43.2%～47.3%.(2)Compared with TFP,RFP significantly reduced available P in 0-60 cm soil layer,and the greatest reduction occurred in 20-40 cm(40.29%).Compared with CFP,OFP significantly increased the available P in 0-60 cm soil layer in vegetable fields,with the greatest increase(52.44%)was found in 20-40 cm soil layer.Compared with TFP,RFP significantly decreased total phosphorus(TP)leaching by 16.02%in vegetable fields.Compared with CFP,OFP significantly increased TP leaching by 30.43%.P leaching in response to RFP was influenced by P application rate,and the contribution rate was 34.49%,followed by soil organic matter(14.49%)and TP(12.12%).P leaching in response to OFP was influenced by various factors,and the contribution rate of rainfall was 16.05%,followed by soil organic matter(12.37%),soil bulk density(12.07%),TP(11.65%),pH(11.41%)and phosphorus application(10.44%).(3)The leaching trial with different organic fertilizer replacement proportions showed that the organic-inorganic combination significantly reduced nitrate leaching compared with chemical fertilizer alone.30%and 70%organic substitution decreased nitrate leaching by 23.14%and 64.04%,respectively;TP leaching was higher by 1.84 times in treatment with 30%organic phosphorus substitution and 1.88 times in treatment with 30%organic nitrogen substitution compared with chemical fertilizer alone.Total nitrate leaching and TP leaching were significantly positively correlated.Nitrate leaching mainly occurred in the early leaching period,while TP leaching occurred throughout the whole leaching period.Redundancy and correlation analysis showed that soil nitrate,TP and organic matter content were the main factors influencing the leaching of N and P under the same water input,with contributions of 38.8%,17.3%and 10.4%,respectively.In summary,N fertilizer reduction,organic-inorganic application and inhibitor regulation all could effectively reduce nitrate leaching in vegetable field.Phosphorus reduction is an efficient way to reduce total phosphorus leaching,while the combined application of organic-inorganic fertilizer increased the risk of total phosphorus leaching.The results can provide a theoretical basis for the development of optimal nutrient management strategies in vegetable production.