Different New Fertilizers On Typical Vegetable Production In Chongqing Comprehensive Evaluation Of Agronomic,Environmental And Economic Effects

The vegetable industry is one of the pillar industries for the agriculture in Chongqing,and Tongliang District,as one of the four major vegetable supply areas in the main metropolitan area of Chongqing,is a typical advantageous production area for vegetable cultivation in Chongqing.However,the intensive vegetable production in Tongliang is characterized by the excessive fertilizer application and the lack of special formula fertilizer for vegetables,the climate of this area by high temperature and rainfall,and the soil in this area by thin layer,light texture and weak fertilizer retention capacity,resulting in serious fertilizer loss and high environmental cost in the process of vegetable production,which seriously restrict the green production of vegetables in Tongliang District.Therefore,this study combines the investigation of vegetable production status and field experiments to,on the one hand,identify the resource inputs,the soil nutrients and the environmental cost of the production of typical vegetables in Chongqing and clarify the main limiting factors of green production;on the other hand,comprehensively evaluate the effects of different new fertilizer products（slow-release fertilizer and stable fertilizer）on the agronomic,environmental and economic effects of typical open field vegetables（kale and pepper）in Chongqing.The main findings are as follows:（1）The current nutrient inputs of open field vegetables in Tongliang District are high,and their average total inputs of nitrogen,phosphorus and potassium nutrients are504 kg/ha,332 kg/ha and 381 kg/ha respectively;the fertilizer application,in which the basal fertilizer is emphasized but the chasing fertilizer is neglected,is unreasonable.The proportion of the basal fertilizer reaches 70%.Nutrient inputs are different among different vegetable types,ranking from high to low as follows:eggplant>tomato>kale（lotus white）>pepper.The soil for typical vegetables in Tongliang has high N,P and K nutrient contents and medium organic matter content.The average organic matter content,p H value,alkaline dissolved N,effective phosphorus and fast-acting potassium contents in it are 22.3 g/kg,6.7,151 mg/kg,69 mg/kg and 308 mg/kg,respectively.The soil nutrient contents of different vegetable fields are different.The kale field has the highest alkaline nitrogen and effective phosphorus;the tomato field has the highest fast-acting potassium.The environmental cost of open field vegetable production in Tongliang District is high.The active N loss and GHG emission per unit area are 193 kg N/ha and 7125 kg CO₂-eq/ha,respectively.（2）The results of kale field trials show that compared with the customary fertilization used by the local farmers,under the optimized fertilization management with different new fertilizer products（slow and controlled release fertilizers and stable fertilizers）,in which nitrogen,phosphorus and potassium fertilizers are reduced,on average,by 36.9%,65.2%and 62.1%respectively,the total and commercial yields of kale are increased by 4.97%and 6.87%respectively,the utilization of nitrogen,phosphorus and potassium fertilizers by 153%,428%and 472%respectively;the active N loss and greenhouse gas emission per unit of yield are decreased by 39.2%and 30.2%respectively,while the economic efficiency is increased by 13.8%.The optimized fertilization with stable formula fertilizer with nitrification inhibitor DMPP displays the best effect Overall.By using it,significantly increasethe kale yield,the commercial yield,the utilization of N,P and K fertilizer and the economic efficiency are increased by 7.50%,8.06%,190%,324%,588%and 18.4%respectively,compared with farmers’customary fertilization;and the active N loss and GHG emission per unit yield are significantly reduced by 40.7%and 31.4%respectively.（3）The results of pepper field trials show that compared with the customary fertilization used by the local farmers,under the optimized fertilization management with different new fertilizer products（slow-release fertilizer and stable fertilizer）,under optimized fertilization management,in which the dosages of nitrogen,phosphorus and potassium fertilizers are reduced,on average,by 55.7%,71.8%and 50.8%respectively,the total yield of pepper is increased by 6.33%on average,the utilization of nitrogen,phosphorus fertilizer and potassium fertilizer by 108%,296%and 74.8%on average.The average reduction of active nitrogen loss and greenhouse gas emission per unit of yield is 57.9%and 49.2%respectively,while the average increase of economic efficiency is 11.6%.The best overall effect is achieved by optimizing the fertilizer application with nitrification inhibitor DMPP,which significantly increases the pepper yield,N,P and K fertilizer utilization and economic efficiency by 11.7%,114%,313%,94.6%and 18.9%respectively,and significantly reduces the active N loss and GHG emission per unit yield by 60.0%and 51.7%respectively.In conclusion,the typical open field vegetables,pepper and kale,in Chongqing are currently produced with high nutrient inputs and high environmental cost.The vegetable yield,the nutrient uptake rate,the fertilizer utilization and the economic efficiency can be increaed and the environmental cost can be decreased by optimizing the total fertilizer dosage by means of using the root layer nutrient regulation technology as a grip and allocating the the nutrient ratio based on the principle of crop nutrient uptake rules and replacing traditional compound fertilizers with new fertilizer products（nitrification inhibitor and controlled release nitrogen fertilizer）.This study is an important guideline for achieving green vegetable production in Chongqing.