Carbon Footprint And Water Footprint Of Scale Pig Farms Based On Life Cycle Theory

The livestock and poultry farming industry occupying a decisive role in China's agricultural production,however,the heavy pollution and high water consumption brought by it are indisputable.The indicator of pollution and water consumption in livestock and poultry farming is mostly the source of pollutant emissions and the reuse rate of fresh water,in recent years,carbon footprints and water footprints have gradually been introduced to assessment.As pig farming occupies a large proportion in livestock and poultry farming,carbon footprint and water footprint are used to assess the carbon intensity and water intensity of scale pig farms,it has important practical significance to regulate the water saving,emission reduction,energy conservation of livestock and poultry farms,and promote the healthy development of livestock and poultry farming.However there are few research about carbon footprint and water footprint for scale pig farming in China,and there is no accounting method for the carbon footprint and water footprint of scale pig farms which adapted to China's specific conditions,especially data collected directly from producers.This study took the scale pig farm as the research object,according to the carbon footprint and water footprint assessment framework,based on the life cycle assessment theory,combined with the actual situation of China's pig farming,established the method to calculate the carbon footprint and water footprint of scale pig farms.Used this method,an empirical study is conducted on typical pig farms in Chongqing with different scales,different reproductive methods,and manure treatment methods,explored the influencing factors to carbon footprint and water footprint in pig farming,in order to assess the carbon footprint and water footprint of livestock and poultry farming in China,formulate energy-saving,water-saving and emission-reduction policies,and provide important reference and technical support for mitigating carbon emission intensity and water resources pressure.The main conclusions are as follows:?1?Based on the life cycle assessment theory,scale pig farm"forage planting"to"manure return field"as the research system,from forage supply?planting and processing?,production data transport,pig breeding?pig enteral fermentation and farm energy consumption?,manure management?manure treatment,manure return?and other stages,established the carbon footprint and water footprint accounting method system of scale pig farm,and confirmed the relevant parameters combined with the actual situation of China's pig breeding.On this basis,according to the scale of farming?large,medium,small?,reproductive methods?self-breeding,and pig fattening?,manure treatment?anaerobic digesters,composts,and thicker mats?,stratified random sampling method to screening 9 typical scale pig farms in Chongqing to conduct field research.?2?Carbon footprint of typical scale pig farms results show:farming scale had a significant impact on carbon footprint,manifest as mall-scale pig farms?3.73kgCO₂-eq/kg?>large-scale pig farms?2.79 kgCO₂-eq/kg?>medium-scale pig farms?2.90 kgCO₂-eq/kg?;manure treatment also had a major impact on carbon footprint,manifest as composting pig farms?3.42 kgCO₂-eq/kg?>anaerobic digester pig farms?2.81 kgCO₂-eq/kg?;but the reproduction method had less influence on the carbon footprint.?3?The results of the water footprint of a typical scale pig farms show that the farming scale also had greater impact on the water footprint,manifest as small-scale pig farms?3.04 m³/kg?>large-scale pig farms?2.48 m³/kg?>medium-scale pig farms?2.33m³/kg?;the manure treatment method also had an impact on the water footprint,manifest as the composting pig farm?2.71 m³/kg?>the anaerobic digester pig farm?2.50 m³/kg?;the impact of reproduction method on the water footprint is also small.?4?Calculated the carbon footprint contribution rate of different stages and different greenhouse gases found that the forage cultivation and processing stage was the most important contributor to the carbon footprint,with over 40%of all pig farms,the contribution rate of carbon footprint was increasing along with the expansion of farming scale,and over 60%of large-scale pig farms;but,the contribution of energy consumption was the opposite,decreases with the expansion of the farming scale,its contribution rate was reduced by about 8%;The changes in the contribution rate of carbon footprint in manure treatment and manure returning were mainly due to differences in the manure treatment systems.CO₂ was a major contributor to carbon footprint in small-scale pig farms,the average contribution rate was 56.1%;in large-scale and medium-scale pig farms,N₂O contributed a lot to the carbon footprint.?5?For the water footprint,the most important contributor to the water footprint was the manure treatment gray water,which exceeds 70%,the contribution rate of water footprint was decreasing along with the expansion of farming scale,contribution rate decreased by about 5%;The water footprint of the farm breeding also decreases with the expansion of the farming scale,while the contribution of the forage cultivation was increasing.Gray water footprint had a higher contribution to pig farm water footprint than blue water footprint,and the gray water footprint contribution rate were exceeds70%,and the small pig farms was approaches 80%.?6?By analyzing the sensitivity of each stage found that changes in forage cultivation and processing stage had the most significant impact on carbon footprint,sensitivity|G|were between 0.231 to 0.339,followed by the farm energy consumption stage,|G|between 0.106⁰.292,with the farming scale expanding,the sensitivity of forage cultivation and processing and manure returning were gradually decreasing,but the energy consumption sensitivity was opposite.The change of the manure treatment grey water footprint had the most significant impact on the water footprint,|G|exceeded0.72,followed by the forage cultivation and processing stage,|G|between 0.156⁰.288.While analyzing the sensitivity of different factors,the breeding cycle and body weight of pigs had greater sensitivity to carbon footprint and water footprint.