Study On Emission Reduction And Yield Increase Potential Of Potato Field Under Different Climate Backgrounds Based On DNDC Model

The formation of N₂O emission and yield in farmland is closely related to fertilization and climate.In order to explore the potential of soil N₂O emission reduction and yield increase in potato field under different fertilization methods and sowing dates in different climate year types,this paper used the precipitation and temperature data of 30 years from 1990 to 2019 in Shenyang to classify the climate patterns,took potato field as the research object,and set four nitrogen gradients,including no nitrogen(0 kg·hm^-2),low nitrogen(60 kg·hm^-2),medium nitrogen(120 kg·hm^-2)and high nitrogen(180 kg·hm^-2).In-situ observation of soil N₂O emission was carried out by static box gas chromatography,and then the De Nitrification–De Composition（DNDC）model was used to explore the potential of yield increase and emission reduction in potato field under different climate patterns.The results showed that:（1）DNDC model could accurately simulate the N₂O emission flux and yield in potato field,and the model efficiency indices were 0.45—0.88 and 0.85—0.91,respectively.（2）DNDC model was used to simulate the optimal fertilization amount for yield increase and emission reduction in potato field under different precipitation patterns.The results showed that potato yield increased first and then decreased with the increase of fertilization amount,while N₂O emission flux showed a constant increasing trend.The optimal fertilization amount was 45—60 kg·hm^-2 in dry years,75—90 kg·hm^-2 in normal years and 105—120 kg·hm^-2 in wet years under the premise of increasing yield and reducing emission.（3）On the premise of optimizing the amount of fertilization in each year,the appropriate fertilization depth and proportion were put forward.In dry and normal years,when the fertilization depth is 10—15 cm and the base dressing ratio is 50%+50%,the model simulation reaches the optimal yield and the emission intensity is the lowest.In wet years,the yield and N2O emission increase with the increase of fertilization depth.When the fertilization depth is20 cm and the base dressing ratio is 60%+40%,the emission intensity is the lowest.Sowing with this fertilization method is conducive to increasing production and reducing emission.（4）The sowing of warm dry year and warm wet year in advance to April 1st is helpful to increase the yield,and the emission intensity of potato field is also small at this time;In rainy and normal years,maintaining the local conventional sowing date（April 10th）will help to achieve the effect of increasing production and reducing emission;Delaying sowing to April15th in a less rainy year will increase production and reduce emissions in potato fields;High temperature year,low temperature year and cold wet year,delaying sowing to April 20th will achieve the effect of increasing production and reducing emission.