Effects Of Carbon And Nitrogen Managements On Greenhouse Gas Emissions And Crop Yield In A Maize-wheat Rotation System

To compare the effects of different carbon and nitrogen management for crop yield?quality and greenhouse gas emissions?CO₂,CH₄,N₂O?in maize-wheat rotation,an annual experiment was conducted in Jianghuai Region.Trial was designed with 6treatments;control treatment(CK:0 N kg·hm^-2),traditional fertilization treatment(CN:360 kg N·hm^-2),reduced nitrogen treatment(RN:240 kg N·hm^-2),control and straw incorporation?CK+S?,traditional and straw incorporation?CN+S?,reduced nitrogen and straw incorporation?RN+S?,s means straw incorporation.Static chamber-gas chromatographic technique was used as the in situ monitoring the phenomenon of CO₂?CH₄?N₂O emissions and determing the yield and quality of maize and wheat.The main outcomes of this trial are as under:?1?In maize-wheat rotation,nitrogen fertilizer and straw incorporation could promote CO₂?N₂O emissions,straw has greater effect on CO₂ emission than nitrogen fertilizer and nitrogen is the main driving factors in N₂O.CH₄ emissions promoted by nitrogen fertilizer and straw.Maize-wheat-year cycle,integrated Warming Potential of CN(7662.11±581.12kgC·hm^-2)is higher than RN(7337.79±354.65kgC·hm^-2)and CN+S(9312.74±200.35kgC·hm^-2)is higher than RN+S(8509.50±336.43kgC·hm^-2)as compared with no straw incorporation.RN+S(8509.50±336.43kgC·hm^-2)is higher than RN(7337.79±354.65kgC·hm^-2)and CN+S(9312.74±200.35kgC·hm^-2)is higher than the CN(7662.11±581.12 kg C?hm^-2).Wheat also showed the similar results.This show that an increase of straw incorporation and nitrogen fertilizer would promote the warming potential of greenhouse gases,but the effect of straw incorporaton will be greater.In maize-wheat rotation system appears to be source of N₂O and CO₂,but CH₄ sinks in Jianghuai Region.?2?Straw incorporation could promote CO₂?N₂O emission in the wheat early growth and the whole growth stage of maize,nitrogen fertilizer affects the whole growth period,which during winter is weak.CH₄ emission from different treatments in maize season was zero emission;Nitrogen fertilizer is negatively correlated with CH₄emission in wheat season;C unit emission intensity is not increased with the increase of nitrogen fertilizer and has a tendency to reduce after the first increase.?3?Maize-wheat rotation in greenhouse gas emission is stronger than the correlation between soil moisture and soil tenperation.Different treatments in maize season,emissions of CO₂,N₂O correlation with nitrate and ammonium is no or weak and strong,and the rest treatments are medium.In wheat season,ammonium correlation with CO₂,CH₄ and N₂O emission is stronger than nitrate.Straw and the nitrogen can contribute to increases in nitrogen emission factors.?4?Maize-wheat rotation system,CN yields(17403.89±166.64 kg·hm^-2)significantly higher than CK(11559.52±263.71 kg·hm^-2),and lower than RN(18239.19±829.05kg·hm^-2)but no significantly,it shows That nitrogen can increase the output of maize-wheat rotation,but more than the optimum amount of nitrogen will reduce production.RN+S yield(18527.71±450.39 kg·hm^-2)higher than RN(18239.19±829.05 kg·hm^-2),CK+S yield(12622.04±764.82 kg·hm^-2)higher than CK(11559.52±263.71kg·hm^-2),CN+S(17279.15±890.12kg·hm^-2)of production less than CN(17403.89±166.64 kg·hm^-2),it shows that description straw combined with appropriate amount of nitrogen is required to achieve the best effect.Combined application of nitrogen fertilizer with straw incorporation has a significant effect on ear width of maize?1000 grain weight and 1000 grain weight of wheat?wheat ear number?kernel number per ear;Combined application of nitrogen fertilizer with straw incorporation has a significant effect on protein of maize and protein of wheat?wet gluten?sedimentation value,but with the increase of nitrogen wheat starch showed a decrease of trend,and no significant effect on maize fat and starchthe effect of straw incorporation on the supply of ammonium nitrogen in the maize and wheat season is not significant;compared with the traditional nitrogen treatment,the ammonium nitrogen from nitrogen reduction treatment do not significantly reduce;nitrate nitrogen supply in treatments related with straw application is small in the early days and then became large in the latter periods;compared with CN,the content of nitrate nitrogen in RN decreased significantly;under the same nitrogen fertilizer,the agronomic efficiency of treatments with straw application is lower than that of treatment without straw addtion and they are opposite in the maize season;Under the CN,the partial productivity of nitrogen in wheat and maize was lower than RN.From the perspective of ensuring production and environmental protection,nitrogen reduction and application of straw would not cause a signficant reduction in yield,and be suitable for planting in the Yangtze-Huaihe area.