| 7 | INTEGRATED CROP-LIVESTOCK SYSTEMS:LESSONS FROM NEW YORK,BRITISH COLUMBIA,AND THE SOUTH-EASTERN UNITED STATES显示文摘Livestock production in the United States(US)and Canada is diverse,but shows a common trend in most livestock sectors toward fewer farms producing the majority of animal products despite a large number of farms still small in production scale.The migration to larger and more concentrated animal feeding operations in beef finishing and poultry,swine,and dairy production allows processors to streamline supplies to meet market demand for abundant,low-cost livestock products,whether that be for packaged meat,dairy products,or eggs.With concentration of livestock operations comes the challenge of managing manures.When sufficient land is available and nutrients are needed,livestock manure is an excellent nutrient source and land application is the preferred method of recycling this resource.However,when livestock production is constrained in a geographical area and animal densities are high,manure may become an environmental liability with potentially greater risk for runoff and leaching of nutrients,emission of odors,ammonia,and greenhouse gases,and release to the environment of pathogens and chemicals of emerging concern.Addressing these challenges now and into the future requires learning from mistakes and adopting successful approaches.We describe different levels of integration between livestock and crop producers in New York,British Columbia,and the south-eastern US as learning opportunities to improve economic and environmental sustainability.Examples show that effective solutions should recognize(1)manure has value and is not just a cost,(2)farmers,farm advisors,extension educators,nutrient management planners,crop advisors,nutritionists,state agency personnel,regulators,and university researchers need to be active participants in development of solutions,and(3)change to a sustainable future requires a combination of government regulation and outcome-based incentives. | Alan FRANZLUEBBERS Derek HUNT Gary TELFORD Shabtai BITTMAN Quirine KETTERINGS | 2021 | Frontiers of Agricultural Science and Engineering2021，8，1： | 0 |
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