Agronomic And Environmental Effects Of Nitrogen Management On Potato In Northern China

Potato is the main food crop in China.Due to the limitation of test conditions,the recommendation and application of nitrogen fertilizer is relatively blind,which directly affects the soil nitrogen supply,potato nutrient absorption and yield formation,as well as greenhouse gas emissions.To this end,this paper uses the potato recommended fertilization method based on yield response and agronomic efficiency developed by our project team and the corresponding nutrient expert system?Nutrient Expert,referred to as NE?to start potato nutrient gradient test in Heilongjiang,Jilin,Shanxi,Gansu and Inner Mongolia to clarify the effects of nitrogen nutrients on potato yield,nutrient absorption,nitrogen use efficiency and soil nitrogen balance,and select black soil in Jilin to carry out potato greenhouse gas emission studies under different nitrogen gradients to clarify the greenhouse effect of different nitrogen application rates during potato growth period,and finally evaluated the agronomic and environmental effects of nitrogen nutrient management in the potato NE system.The main progress achieved by the paper is as follows:?1?With nitrogen rate increased,potato tubers yield at each site in the north China increased.When nitrogen rate reached the recommended nitrogen rate of NE,the output of each site reached the maximum.The potato yield of each nitrogen treatment was significantly higher than that of no nitrogen treatment?P<0.05?.?2?With the increase of nitrogen rate,the absorption of potato tubers,straws and whole plant nitrogen at each site increased.When nitrogen rate reached the NE recommended nitrogen rate,nitrogen absorption reached the maximum value.When nitrogen rate continued to increase,the absorption of nitrogen no longer increased or even decreased,and each nitrogen rate treatment was significantly higher than that without zero nitrogen rate?P<0.05?.Nitrogen partial productivity,nitrogen agronomic efficiency,and nitrogen recovery efficiency decreased with the increase of nitrogen application,and the differences between the treatments reached significant levels?P<0.05?.?3?With the increase of nitrogen rate,the content of nitrate nitrogen in soil increased significantly?P<0.05?.The nitrogen absorption of crops increased with the increase of nitrogen rate.When the nitrogen rate reached the NE recommended nitrogen rate,the potato nitrogen absorption amount reached the maximum in each growth period.When nitrogen rate exceeded NE rate potato yield didn't increase.Absorption of residual soil nitrogen increased with the increase of nitrogen rate,and the application of nitrogen fertilizer treatment?NE+50%N,NE+40%N treatment?in Shanxi and Gansu experimental site was significantly higher than other treatments?P<0.05?.?4?With the increase of nitrogen rate,the greenhouse gas emission flux generally showed an increasing trend,but it did not affect its emission.N₂O and CO₂ were mainly emitted,while CH₄ is mainly absorbed.After rainfall and nitrogen fertilizer application,all the greenhouse gases had obviously peaks.Most of them changed with the seasons,showing obvious early and late emission fluxes.showed that the emission flux in early and late growth period was low and the emission in middle growth period was high.The total emissions of N₂O,CH₄ and CO₂ in each treatment were significantly higher than that in the NE-N treatment?P<0.05?.The total emissions of N₂O and CO₂increased with the increase of nitrogen rate,while the total emissions of CH₄ increased with the nitrogen rate and the Global Warming Potential decreases with the increase of nitrogen application.The greenhouse gas emission intensity of each nitrogen rate treatment is significantly higher than that of NE-N treatment?P<0.05?,and the emission intensity of NE treatment was lower than that of other nitrogen rate treatments.By comprehensive comparison analysis,it can be concluded that the nitrogen rate with NE recommended is the optimal rate for nitrogen application.In summary,the NE system can recommend nitrogen fertilizer rate for potato in different regions with significantly increasing potato yield and the utilization efficiencies of nitrogen fertilizer,reduced the residual soil inorganic nitrogen and the greenhouse gas emissions.