| China is the largest animal production country in the world.The growth of the animal industry in China leads to seriously environmental problem locally and globally.The increase in animal production has led to the increase in manure generated.In addition to animal production,the subsequent storage of manure with a high concentration of organic matter has also been shown to be an important source of GHG emissions.Large quantities of N are lost as NH3 during the early days of manure storage.Emission of NH3 causes eutrophication and acidification,which leads to the decline of biodiversity and diebacks of forests.Furthermore,C and N gaseous emissions can reduce the agronomic value of manure as soil amendment or fertilizer.Some storage systems(i.e.aerobic composting and anaerobic digestion)have been well studied in terms of NH3 or GHG emissions,but knowledge on the gas C and N emissions and environmental impact of solid manure stored as a pile in the open air are limited.Production of animal is mainly concentrated in China's Yangtze River basin,such as Hunan,Hubei,and Jiangxi provinces.In these regions,manure is mainly applied to fields without any further treatment such as composting.This traditional management approach of manure in China's Yangtze River basin accounts for about 80%of manure in the region.Due to various technological limitations,no systematic studies have been carried out to quantify NH3,N2O,CH4 and CO2 emission factors from storage of solid pig(cattle)manure in China.Therefore,it is essential to measure the C and N gas emissions from such open-pile storage of manure.This study will enable us to determine the contribution of a commonly solid manure management system to global warming and identify mitigation options.At the same time,the objective of this study is to investigate the effects of different managements(i.e.different initial moisture content,covering straw,adding biochar and increasing gap of pile)on gaseous emissions during manure storage.And identify the carbon and nitrogen emission of the line of storage-application in order to quantify gasoes environmental pollution and estimate the nutrient utilization of manure required for sustainable nutrients recycling on agriculture.The main results are as follows:(1)Storage of solid manure was the typical management of manure in China's Yangtze River basin.Seasonal regularity was different between summer and spring during manure storied period.NH3 volatilization was mainly concentrated at the early stage.N2O and CO2 emissions were mainly concentrated at early stage during storage of pig solid manure both in summer and spring.However,CH4 emission was mainly concentrated at the last stage during storage.NH3 volatilization reached at 30%of N lost,and only 2%of N was lost as N2O.In summer of China's Yangtze River basin,air temperature was much high,the gas emission from surface of pile was significantly effected by air temperature.Precipitation increased water contend in pile,and C and N gases emission were significantly effected by water contend in pile.Sping is rainy season in Changsha,persistent rain kept water contend in pile at a high level,therefore,C and N gases emission from pig solid manure were effected by environmental factors in summer,but there was no significant regularity in spring.CH4 emission was produced after precipitation in both seasons.(2)This study investigated the carbon(C)and nitrogen(N)gaseous emissions(N2O,NH3,CO2,CH4)from solid cattle manure management in China.Gases emissions were quantified from static piles over 60 and 55 days during summer and spring respectively in China's Yangtze River basin,using Drager-Tube method and static chamber-gas chromatography techniques.High emissions of NH3 and N2O were observed at the early stage of storage,but high content of CH4 was at the latter stage of storage.During the storage,50%-60%%of the total C in the original pile was lost;CO2 and CH4 emissions accounted for 50%and 10%of C lost respectively.Over the same time,41%of the total N in the original pile was lost;NH3 emissions accounted for 5.20%and 2.24%of N lost respectively.C and N gases emission from cattle solid manure were not effectted by environmental factors in both seasons.Given China's major role in cattle production,further attention should focus on cattle manure management to mitigate its contribution to atmospheric pollution.(3)To realize harmless treatment and resourceful utilization of solid manure,maize straw was mixed with solid manure at a certain proportion for fermentation.The initial water content in the mixture was set as 40%,60%and 80%;the temperature,organic content and carbon and nitrogen gases emissions of the three pile of mixture during storage was detected and analyzed to find a proper condition for high efficient process of piled storage.The result showed that carbon and nitrogen gases emission were affected by initial water.Compared with initial water contend of 40%and 80%,NH3 volatilization was 1.04 g·m-2 initial water contend of 60%treatment,NH3 volatilization could be reduced 24.01%and 1.35%respectively.However,N2O emission could be creased 33.72%and 35.36%under initial water of 60%.CH4 emission was least at 40%treatment,was 1.89 g·m-2.If adjust the water content of compost to 60%during certain stage of fermentation,some indices would change remarkably,indicating that supplement of water during composting would accelerate the process.(4)In this study,different mitigation measures had significantly decreasion on carbon and nnitrogen emissions during storage.Effecting of controlling gas emission were same under different measures,that were stored swine manure coverd by straw(CS),stored swine manure fertilizer mixed by biochar(BS),stored swine manure fertilizer with void expands(OS).Loss of NH3 volatilization and N2O emission can be significantly reduced by other 3 treatments.The treatment of BS could promot process of fermentation.The treatment of OS had useful for harmless treatment and resourceful utilization of solid manure.(5)Agricultral management such as fertilizer or manure application has a substantial influence on NH3,N20 and CH4 emissions and,by understanding this influence,we may devise management strategies to reduce them.An experiment was conducted in greenhouse at Daxing district in Beijing from July to August in 2017,to investigate effects of different fertilizers on NH3,N2O and CH4 emissions.The treatments included control without fertilizer(CK),stored swine manure fertilizer(SS),stored swine manure coverd by straw(CS),stored swine manure fertilizer mixed by biochar(BS),stored swine manure fertilizer with void expands(OS),fertilizer and chemical fertilizer(FC).The fluxes of NH3,N2O and CH4 were collected by DTM method and static-chamber method,respectively.The results showed that during the rapeseed growth season,under the same nitrogen level,compared with SS,BS and OS significantly reduced both of loss of NH3 and N2O.Yield of rapeseed under 6 treatments were BS(54.2 t·hm-2)>FC(50.5 t·hm-2)>OS(41.8 t·hm-2)>CS(40.3 t·hm-2)>SS(40.3 t·hm-2)>CK(25.7 t·hm-2).Temperature was not the impact factor during the spinage planting in greenhouse in summer,but soil water was.Therefore,optimizing manure management reduced loss of ammonia volatilization and N2O emission without decreasing vegetables production.The present data showed that BS and OS would be optimal for better yield and less ammonia volatilization and N2O emission loss.In conclusion,gaseous emissions from the storage of solid manure in China are a major pathway for C and N losses.NH3 and N2O emissions mainly occurred at the early stage of manure storage.Precipitation was expected to increase NH3 and N2O emissions by changing moisture content of the pile;in our study,there was no consistent pattern to suggest that to be the case.The timing of precipation during the storage was likely a key factor.Mitigations of N2O and NH3 emissions from manure should be a key priority.The initial moisture content of manure was different,and the carbon and nitrogen gas emission laws are different in the management process.The optimal management measures can reduce the loss of carbon and nitrogen nutrients in the storage process of manure and reduce environmental gas pollution.Based on cyclic development of farm-land,optimal management measures could reduce the gases emission in link of storage-application,and improve the utilization efficiency of manure,was conducive to agricultural sustainable development cycles. |
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