Effects Of Cover Crop Combined With Manure And Chemical Fertilizer On GHG Emissions In Apple Orchard

Agricultural practices contribute Greenhouse gases to the atmosphere,which potentially affect climate change mainly through trapping of long wave radiation emitted from the earth.This study was aimed to determine the emissions of these three important greenhouse gases（GHGs）released from manure and chemical fertilizer applied fields.The field was divided into two main plots.The first plot was used as cover crop treatment（Brassica rape L）and second plot was used as clean tillage（weed control）treatment.The two plots were further divided into sub-plots where fertilizers were applied into four different levels.The fertilizer treatments include:i)Control（CK）,ii)NPK fertilizer（NPK）,iii)Manure（M）,iv)Manure+NPK（MNPK）.During the whole experiment CH₄,N₂O and CO₂ were taken at different interval and soil SOC,NH₄⁺-N,NO₃^--N were also taken at different intervals.This research result found that cover-cropping systems by Brassica rape L showed a greater emission of greenhouse gases（GHGs）than clean tillage control.1.CO₂ emission variation seasonally in each treatment was consistent,and CO₂ emission flux was significantly positive related to soil moisture content as well as temperature.The average of CO₂ emission on cover crop experiment was higher than clean tillage control by9%.For estimating CO₂ flux on cover crop experiment.The average of CO₂ fluxes order from the highest to the least was M>MNPK>NPK>CK,M treatment showed extremely high CO₂fluxes with 452.583 mg·m^-2·h^-1.For estimating CO2 flux on clean tillage control.The average of CO₂ flux order from the highest to the least was M>NPK>MNPK>CK.M treatment showed the maximum releasing on average of CO₂ flux with 370.276 mg·m^-2·h^-1.2.CH₄ emission flux among all treatments were minor,CH₄ was not the major greenhouse gas discharged in Apple orchard.M and NPK exhibited the emission source of CH₄,but other.Treatments showed less absorption of CH₄.The average of CH₄ emission on cover crop experiment was higher than clean tillage control by 14%.For estimating CH₄ flux on cover crop experiment.The average of CH₄ flux order from the highest to the least was M>NPK>MNPK>CK,M treatment showed the highest CH₄ flux with 0.1302 mg·m^-2·h^-1.For estimating CH₄ flux on clean tillage control.The average of CH₄ flux order from the highest to the least was NPK>M>MNPK>CK.NPK treatment showed the highest CH₄ flux with 0.0965 mg·m^-2·h^-1.3.N₂O emission variation seasonally in each treatment was consistent.For estimating N₂O flux on cover crop experiment.The average of N₂O flux order from the highest to the least was NPK>M>MNPK>CK,NPK treatment showed the highest N₂O flux with 0.353mg·m^-2·h^-1.The average of N₂O emission on cover crop experiment was higher than clean tillage control by 10.6%For estimating N₂O emission on clean tillage control.The average of N₂O emission order from the highest to the least was NPK>M>MNPK>CK.NPK treatment showed the maximum N₂O emission with 0.270 mg·m^-2·h^-1.MNPK treatment effectively declined N₂O emission from Apple Orchard.There was a negative relation between N₂O emission flux and the content of soil nitrate nitrogen and ammonium nitrogen showed.The exist of competitive relationship among them.That is to say,directions of sink flow were different among N₂O,Nitrate nitrogen and ammonium nitrogen from soil when soil nitrogen source was certain.According to the study result,the use of chemical fertilizer mixed with manure is considered as the best solution to reduce greenhouse gas emission and is significant to improve the production sufficiency of apple production.Moreover,using chemical fertilizer mixed with manure helps to minimize production cost and also enhance soil fertility and quality.However,the averages of GHGs emission are influenced by environmental factors such as changing seasonal,temperature,soil properties and rainfall.