Recoupling Industrial Dairy Feedlots and Industrial Farmlands

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Characterization of Natural and Affected Environments

Recoupling industrial dairy feedlots and industrial farmlands mitigates the environmental impacts of milk production in China Xing Fan, Jie Chang, Yuan Ren, Xu Wu, Yuanyuan Du, Ronghua Xu, Dong Liu, Scott X Chang, Laura A. Meyerson, Changhui Peng, and Ying Ge Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b04829 • Publication Date (Web): 08 Mar 2018 Downloaded from http://pubs.acs.org on March 12, 2018

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Environmental Science & Technology

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Recoupling industrial dairy feedlots and industrial farmlands mitigates the

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environmental impacts of milk production in China

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Xing Fan,† Jie Chang,† Yuan Ren,† Xu Wu,‡ Yuanyuan Du,† Ronghua Xu,† Dong Liu,§ Scott

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X Chang,|| Laura A. Meyerson,┴ Changhui Peng,# Ying Ge†,*

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†

College of Life Sciences, Zhejiang University, Hangzhou 310058, China

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‡

Zhejiang Provincial Economic Information Center (Zhejiang Center for Climate Change

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and Low-carbon Development Cooperation), Hangzhou, 310006, China

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§

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Nanjing 210042, PR China

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||

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Canada

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Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection,

Department of Renewable Resource, University of Alberta, Edmonton T6G 2E3, Alberta,

┴

Department of Natural Resources Science, University of Rhode Island, Kingston, RI

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02881, USA

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#

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Quebec at Montreal, Montreal, QC H3C 3P8, Canada

Department of Biological Sciences, Institute of Environment Sciences, University of

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ACS Paragon Plus Environment


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ABSTRACT

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Dairy production is becoming more industrialized globally, especially in developing

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countries. The large amount of animal wastes from industrial feedlots cannot be fully used

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on nearby farmlands, leading to severe environmental problems. Using China as a case

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study, we found that most dairy feedlots employ a semi-coupled mode that only recycles

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solid manure to farmlands, and only a few dairy feedlots employ a fully-coupled mode that

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recycles both solid and liquid animal manure. To produce one ton of milk, the fully-coupled

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mode could reduce greenhouse gas (including carbon dioxide, methane, and nitrous oxide

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in this paper) emissions by 24%, ammonia emissions by 14%, and N discharge into water

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by 29%, compared with the semi-coupled systems. Coupling feedlots with constructed

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wetlands can further result in greater mitigation of N leaching into groundwater. However,

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the fully-coupled system has not been widely used due to the low benefit to farmers and the

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institutional barrier that the feedlot owners have no right to use adjacent farmlands. Since a

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fully-coupled system improves net ecosystem services that favor the public, a policy that

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supports removing the economic and institutional barriers is necessary. Our approach

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provides a template for mitigating environmental impacts from livestock production

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without sacrificing milk production.

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INTRODUCTION

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Global dairy production has doubled over the past five decades, and it will continue to

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grow by approximately 50% from 2011 to 2050.1,2 The growth of global dairy production

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will mainly occur in emerging economies,2,3 where dairy production is transitioning from

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extensive to industrial systems.4,5 The industrialization of dairy production improves

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production efficiency but also results in many environmental problems due to the

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difficulties in handling and disposing of excessive animal waste, especially liquid waste.6,7

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Manure management for industrial livestock production results in a substantial contribution

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to climate change8 and plays an important role in eutrophication, groundwater

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contamination,9 and outdoor particulate matter pollution.10,11 How to achieve sustainable

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industrialization that produces more dairy products with less environmental and human

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health impacts is a challenge.

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In an industrial production system, the decoupling between animal and land

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exacerbates environmental degradation.9 Decoupling hinders the recycling of manure to

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farmlands, and as a result, both inadequately treated waste, especially liquid waste, from

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specialized feedlots and excessive mineral fertilizer application on farmlands are severe

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threats to the environment.9,12 Recoupling of crop and livestock production is proposed to

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mitigate environmental pollution.9,13,14 Recoupling through reusing animal manure on

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farmlands can reduce N pollution from industrial feedlots and croplands15,16 and improve

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resource use efficiency in the crop-livestock system, turning the linear nutrient flow

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(plant-animal) to a plant-animal-plant cycle.13,15 Recoupling through introducing grasslands

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or forage within arable cropping systems can also improve the environmental performance

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of intensive farmlands, such as by increasing the soil organic matter level, reducing

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agrochemical usage, and reducing soil erosion and N leaching.17-20 Nevertheless, specific

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measures of recoupling affect the realization of these benefits. Even in developed countries,

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there are still improper practices in recycling manure that cause substantial pollution, such

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as long-term outdoor exposure before manure spreading, which releases terrible smells and

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maximizes ammonia (NH3) emissions.21,22 Moreover, many industrial livestock feedlots in

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developing countries only use solid animal manure in farmlands and discharge liquid waste

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into the environment.5,23 Designing modern recoupled systems with improved technologies

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is crucial to minimizing pollution while meeting the growing demand for animal products.14

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For better implementation of recoupling, there is an urgent need to conduct

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comprehensive assessments of the environmental performance of recoupling and relevant

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socio-economic factors that constraint its promotion.24 Some efforts have been carried out

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to assess recoupling that occurred on the same lands or between spatially separated

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cropping and livestock systems.13,25 For large confined livestock operations, recoupling

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between spatially separated systems is the more common form, but there is a lack of

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evaluations of the environmental impacts on a regional scale.18,23,26 In addition, current

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studies on recoupling pay little attention to the details of manure management, while

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studies on manure management technology only focus on the stages after animal excretion.

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For example, as an engineered ecosystem with the main purpose of wastewater

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treatment,27,28 constructed wetlands (CWs) have been proven effective at treating liquid

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animal manure through mechanisms such as plant absorption (Table S1),29,30 but

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assessments on the recoupled system of livestock feedlots and CWs are lacking. Moreover,

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only a few environmental parameters are considered in previous assessments, which limit

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the comprehensive understanding and spread of recoupling.

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In this study, we conducted a life cycle assessment of the entire milk production chain

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that includes four stages: feed crop production, feed processing, dairy cow rearing, and

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milk processing (Figure S2). We used China as a case study because it has rapidly grown

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into a new global player in milk production (the third largest in the world).1 We compared

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the environmental performances of the semi-coupled (only solid dairy manure is recycled)

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and the fully-coupled (both solid and liquid dairy manure are recycled) systems. Total

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nitrogen (N) loss and the environmental impacts including nitrous oxide (N2O), methane

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(CH4), carbon dioxide (CO2) and NH3 emissions and N discharge into water were included

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in the comprehensive assessment. We then analyzed the costs and benefits of these coupling

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modes and the land requirement, which is a significant factor to be considered in

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developing countries with substantial land pressure. As an additive measure for ecological

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and economic performances, ecosystem services under different coupling modes are

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assessed and compared. Furthermore, we estimate the mitigation potential of implementing

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fully-coupled systems for the whole dairy sector in China by 2020.

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MATERIALS AND METHODS Data sources. There are three main data sources in this study: our field survey,

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Chinese official statistics, and the synthesis of literature. We investigated 122 dairy feedlots

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in 24 provinces across China through interviews and web searches from 2014 to 2016

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(Figure S1) to acquire information about the land area, herd structure and milk yield of

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dairy cows, feedstuffs, manure management (collection, storage, treatment), and manure

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recycling practices (Table S2, S3). The basic information related to China’s dairy sector,

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such as milk production and number of dairy cows in each dairy system, fertilizer

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application rates and yield of feed crops, and energy consumption in dairy feedlots, was

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taken from Chinese statistical records (e.g., Figures S15a, S16a, and Table S6); coefficients

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for calculating the N fluxes and the environmental impacts, such as N deposition rates, gas

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emission factors, and farmland leaching/runoff rates, were obtained from the synthesis of

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literature (e.g., Tables S5, S9, and S10). Details are described in Supplementary

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Information (SI).

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Industrial dairy production systems. Two coupling degrees are distinguished

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according to manure management (Table S4): semi-coupled and fully-coupled. In a

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semi-coupled system, only solid dairy manure was used on farmlands while the liquid

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manure is discharged into water or dried in situ. In a fully-coupled system, both solid and

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liquid dairy manure is treated and recycled to farmlands. In our survey, the complete

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decoupled system, in which neither of the solid nor liquid dairy manure is used on

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farmlands, does not exist in China; fully-coupled systems only account for 5% of the

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industrial dairy feedlots; most of the industrial dairy feedlots employ the semi-coupled

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mode. In a semi-coupled system, solid manure is composted for at least one month before it

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is applied to land. In a fully-coupled system, popular practices include biogas digestion for

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slurry, composting solid manure, and storage of liquid manure before application (Table

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S2).

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Based on the results of our field survey, we calculated the two modeled fully-coupled

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systems: fully-coupled between industrial feedlots and industrial farmlands (FCIIC) and

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fully-coupled between industrial feedlots and constructed wetlands (FCICW). In the FCIIC,

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besides the abovementioned popular practices, a storage covering measure is also adopted

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as it has been proved effective at reducing NH3 volatilization.31 In the FCIIC, after

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anaerobic fermentation, the separated solid fraction is composted for an average period of

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one week, and the separated liquids are stored in a covered tank for three weeks before

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application (see SI for details). The application of solid manure is the same as that in a

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semi-coupled system. The liquid manure is applied to industrial farmlands, which are

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intensive farmlands with high levels of inputs and outputs per unit of land area and

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mechanized equipment. The basic requirement of industrial farmlands is to be equipped

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with a fertigation pipeline system through which the liquid manure is pumped out from the

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storage tank and distributed to land. In fact, CWs can also be regarded as industrial

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farmlands for feed planting as well as wastewater treatment (see SI for details, Table S1). In

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addition to pipeline systems and valves to control the influent and effluent, CWs usually

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have artificial structures with an impermeable bottom that can prevent nitrogen leaching

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into groundwater. Thus, we proposed and assessed the FCICW based on a previous study of

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our research group,28 even though we did not find the same case in our survey as the

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FCICW proposed. In the FCICW, manure management is the same as that in the FCIIC,

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and CWs replace farmlands as the liquid manure receiver. The land application methods in

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this study are surface spreading for chemical fertilizers, incorporation for solid manure, and

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band spreading for liquid manure.32

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Calculation of nitrogen flux and environmental impacts. We calculated the

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parameters using the STELLA graphic programming system (High Performance System

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Inc., Version 9.1.2). For each coupling mode, the calculator includes four parts: Part 1 is

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used to simulate N fluxes for the entire milk production chain, part 2 is used to calculate

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NH3 emissions, part 3 is used to calculate GHGs emissions, and part 4 is used to calculate

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N discharge into water (Figures S3-S6). The sources of GHGs (N2O, CH4, and CO2)

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include the production of chemical fertilizers, the application of chemical fertilizers and

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manure, enteric fermentation, manure management, energy use, and transportation. The

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sources of NH3 considered include the following: fertilizer production, fertilizer application,

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N fixation, animal manure management, and transportation. The effects of different manure

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management practices on GHGs and NH3 emissions were considered in our calculations

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(see SI for details). N discharge into water occurred mainly through leaching and runoff

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from farmlands, processing losses from feed crop processing plants and milk processing

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plants, and manure management (see the SI for details).

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Calculation of ecosystem services. Based on the framework of the Millennium

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Ecosystem Assessment33 and other studies,28,34 we evaluated ecosystem services (including

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provisioning, regulating, and cultural services) and dis-services (Figure S7) associated with

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milk production. The ecosystem services and dis-services of dairy feedlots and the entire

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milk production system where nutrient recycling occurred were calculated. Specifically, we

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quantified and monetized milk provision, water saving, water regulation, and four

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regulating dis-services (GHG emissions, NH3 emissions, and surface water and

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groundwater N pollution); cultural services such as education could not be monetized (see

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the SI for details of calculation). Among the total 122 dairy feedlots in our investigation,

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108 dairy feedlots across 24 provinces in China (Table S3) were used to calculate

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ecosystem services and dis-services, due to data availability. We investigated the net

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ecosystem services of each dairy feedlot as it transforms between different coupling modes,

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regardless of its original coupling mode, to avoid the dairy feedlot (such as breeding

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density and specific climatic conditions) having a greater influence on net ecosystem

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services than the coupling mode.

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Cost-benefit analysis. The private costs and benefits of dairy feedlot owners and feed

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crop farmers were analyzed. The costs include material and service costs (such as feed, fuel,

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depreciation of fixed assets, disease prevention, repair and maintenance, etc.), labor costs,

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and land rent. The benefits include products and subsidies. The specific items related to the

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costs and benefits are shown in Tables S16 and S17. We highlighted the changes in costs

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and benefits transitioning between coupling modes, and the other unchanged items are

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summed as “other” in Tables S16 and S17.

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Projection of the environmental impacts of China’s milk production in 2020. We

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used 2011 as the reference year because of data availability, and 2020 as the target year

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because of the ‘13th Five-Year Planning’ for China’s dairy and the target of zero fertilizer

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growth by the end of 2020.35,36 To quantify the effects of the technical transformation of

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manure management, three scenarios were analyzed: Scenario 1: business-as-usual (BAU),

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in which the percentages of semi-coupled and fully-coupled systems across national

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industrial dairy production systems are kept at the 2011 level; Scenario 2: all industrial

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dairy feedlots are fully-coupled with industrial farmlands; and Scenario 3: all industrial

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dairy feedlots are fully-coupled with CWs.

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To calculate the environmental impact of national dairy production and the reduction

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potential of technological improvements, we also account for non-industrial dairy

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production systems: grassland-based systems, traditional systems, and collective systems

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(see SI for details).

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RESULTS AND DISCUSSION

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Nitrogen loss. The total N loss when producing one ton of milk in a semi-coupled

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system in China was 36.3 kg N (Figure 1, Figure S8). The total N loss in the FCIIC (30.3

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kg N) and FCICW (23.6 kg N) was 17% and 35% lower than a semi-coupled system,

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respectively. Our results on the status quo systems in China (mainly semi-coupling) are

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lower than that of a previous study (54.5 kg N loss when producing one ton of milk) in

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which the dairy feedlots employed the decoupling mode.5 To produce equal amounts of

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milk products, recoupling reduces the external N input to the system through manure

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recycling, thus reducing N loss and increasing N use efficiency of the whole system. In a

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semi-coupled system, 20% of the N from chemical fertilizers is replaced by manure. In

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fully-coupled systems (FCIIC and FCICW), the managed manure from the dairy feedlots

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can replace 44% of the chemical fertilizer N required by feed crop production. In addition,

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in the FCICW, effluent from the CWs is controllable, and effluent N can be refed into the

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CWs for plant growth, further reducing N loss.

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Greenhouse gas emissions. The total N2O emissions from a semi-coupled system are

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304.2 kg CO2e per ton of milk (Figure 2a). Shortening the exposure time of manure to the

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air can reduce N2O emissions; for example, by shortening the composting period from three

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to one month, approximately 60% of N2O from solid manure can be avoided (Figure 3a,

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3d). However, the current composting period often lasts for several months or even half a

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year. N2O emissions in the FCIIC are 33% lower than those in the semi-coupled system

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(Figure 2a) owing to the shorter exposure time of both solid and liquid manure. Recoupling

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with CWs can further reduce N2O emissions from feed crop production by optimizing the

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hydraulic pattern or28 adding carbon or plant assemblages.37

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The total CH4 emissions from a semi-coupled system are 408.6 kg CO2e per ton of

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milk. The CH4 emissions in the FCIIC and FCICW are reduced by 10% and 12%,

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respectively, compared with a semi-coupled system (Figure 2b). Shortening the exposure

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time of manure reduces CH4 release (Figure 3b, 3e), but practices such as covering and

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biogas fermentation leading to anaerobic conditions are conducive to CH4 production.38

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Retaining the CH4 produced is not beneficial as it can escape at a later stage; therefore,

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burning or combusting the collected CH4 for electricity or heat production is the most

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desirable option.38 The total CO2 emissions from a semi-coupled system are 481.9 kg CO2 per ton of milk.

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The CO2 emissions from the FCIIC and FCICW are reduced by 31% and 42%, respectively,

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compared with a semi-coupled system (Figure 2c). Using solid manure N reduces the CO2

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emissions from chemical fertilizer production by 20%, and using liquid manure N reduces

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CO2 emissions from chemical fertilizer production by another 24%. Substituting biogas for

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fossil fuels to produce electricity or heat avoids another 90.7 kg of CO2 emissions per ton

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of milk.

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The total GHG emissions in a semi-coupled system are 1197.4 kg CO2e per ton of

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milk. The total GHG emissions in the FCIIC and FCICW are 24% and 36% lower,

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respectively, than a semi-coupled system (Figure 2d, Figure S9). The GHG emissions from

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manure management in fully-coupled systems in China are even lower than those in some

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developed countries (Table S12, and S13). Although most of the developed countries have

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recoupled crop and livestock production, there are still improper practices in manure

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management that cause substantial pollution. Modern fully-coupled systems are also

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needed for developed countries to further reduce gaseous pollutants.

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Ammonia emissions. The NH3 emissions from a semi-coupled system are 10.7 kg

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NH3 per ton of milk. The NH3 emissions from the FCIIC and FCICW are 14% and 33%

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lower, respectively, than a semi-coupled system (Figure 2e, Figure S10). Ammonia is

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rapidly lost from manure and the emissions rate declines exponentially with exposure time

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(Figure 3c, 3f). According to the cumulative emissions – exposure time curve we

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established through the literature review (Figure 3f), the mitigation effectiveness of

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shortening the exposure time from several months to one month during composting is

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approximately 14%. In fully-coupled systems, storage coverings and anaerobic digestion

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that can shorten the subsequent compost period to 3~7 days39 further mitigate NH3 release.

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Additionally, CWs can lower their NH3 emissions during plant growth through strong

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artificial management, appropriate structures, and physicochemical environment regulation.

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For example, subsurface flow CWs often have lower ammonia volatilization than surface

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CWs: 0.2%−0.9% of the N loading is lost by NH3 volatilization in subsurface flow CWs,

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while an average of 0.3%−36% (with an average of 15.6%) is lost by NH3 volatilization in

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surface flow (Table S14). However, FCICW has higher NH3 emissions (7.2 kg per ton of

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milk) than low-emission countries (3.3−5.0 kg per ton of milk) in Europe (Table S12),

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which has rigid regulations on NH3 emissions.7 Fully-coupled systems need to combine

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other mitigation techniques such as emissions-free housing systems, application of lignite,

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and precision fertilization to further reduce NH3 emissions in China, but the safety,

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economic feasibility, and willingness of feedlot and farm owners to apply them in an

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accurate and timely fashion are priorities.31,40,41

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Nitrogen discharge into water. The N discharge into water from a semi-coupled

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system is 14.1 kg N per ton of milk and that from FCIIC and FCICW are 29% and

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50%lower, respectively, than a semi-coupled system (Figure 2f, Figure S11). In a

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semi-coupled system, 34.6% of excreta N is recycled to feed crop lands, and in a

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fully-coupled system, 76.4% of excreta N is recycled. However, if not managed well,

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applying liquid manure that can more easily penetrate the soil can increase the risk of N

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leaching. CWs lined with a waterproof membrane are practical alternatives in areas

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suffering severe groundwater pollution.27,28 In the FCICW, the N leaching from liquid

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manure applications would approach zero (Table S15). Furthermore, treated water from

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CWs can be reused to clean animal houses thereby reducing the use of clean water and

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ensuring that there is no N runoff to the surface water. Some European countries also

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discharge large amounts of N into water from milk production (Table S12). In addition,

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phosphate pollution of groundwater caused by manure recycling to the soil has even forced

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the Netherlands to substantially reduce its number of dairy cows in 2017.42 With a

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waterproof membrane at the bottom, CWs should be an effective way to mitigate

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groundwater pollution caused by phosphate as well as nitrate leaching.

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Ecosystem services. Synthesizing environmental performance (regulating services

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and dis-services) and milk production (provisioning services), we quantified the net

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ecosystem services (Figure S7) of dairy feedlots (Table S16) and the entire milk production

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systems (Table 1). The net services of surveyed dairy feedlots that employ semi-coupled

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mode equal 1.5 thousand USD ha-1 on average (Table S16). The net services of dairy

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feedlots employing fully-coupled mode equal 21.1 thousand USD ha-1 on average (Table

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S16; Figure S12). Since the separate improvement of a single process may transfer the

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environmental burden of that process to another process, we also calculated the net

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ecosystem services at the milk production system level where nutrient recycling occurred.

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All the surveyed semi-coupled systems provide negative net services, with an average of

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-663.3 USD ha-1 (Table 1). Transforming from semi-coupled to fully-coupled systems not

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only reduces dis-services but also provides some other services. For example, fully-coupled

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systems reuse liquid waste and thus save irrigation water for feed crops. Transforming to

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the FCIIC, 9% of these systems would turn to provide positive net services, and

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transforming to the FCICW, 66% of these systems would turn to provide positive net

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services (Figure S12). The average net services of the FCIIC and FCICW are improved to

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-289.7 and 28.6 USD ha-1, respectively (Table 1).

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In addition to fully recycling animal manure, diversifying grain cropping systems with

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grasslands and forage crops can further mitigate the negative environmental impacts of feed

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crop production.18-20 Grass-crop rotation can reduce N leaching from subsequent intensive

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cropping systems. A nine-year experiment on water nitrate levels in five cropping/grassland

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systems demonstrated that the introduction of grasslands into arable crop rotation reduced

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N leaching to groundwater by ~50%, and the longer the period that grasslands were within

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the rotation the more the nitrate concentration was reduced.43 Legume-crop rotation, such

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as the introduction of alfalfa into maize fields, can reduce mineral fertilizer inputs while

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maintaining the available N for crops, thus mitigating the GHG and NH3 emissions caused

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by industrial synthesis without a loss in feed crop yield.44,45 Combining the benefits from

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fully recycling manure with these agronomic services provided by converting from

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continuous monoculture to forage-crop rotation, the net ecosystem services of a more

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integrated system are -145.1 USD ha-1, which is an intermediate value between the FCIIC

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and FCICW (Table 1). Forage-crop rotation can also provide some other ecosystem services,

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such as a reduction in soil loss, an increase in soil organic carbon levels, improved soil

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fertility and biodiversity, and weed and pest population control.17,20

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Recoupling has more benefits in specific locations, and different coupling modes can

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be adopted according to local conditions. Recycling manure on higher value crops such as

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fruits and greenhouse vegetables is more economical than recycling manure on forage

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crops.23 According to our survey in Yangling, Shaanxi, receiving manure from a dairy

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feedlot helps a kiwifruit orchard increase its yield and improve the taste of kiwifruit. In

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another case study in Shaoxing, Zhejiang, located in the coastal area of eastern China,

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applying liquid manure from a dairy feedlot nearby improves the buffering capacity of the

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soil and reduces its alkalinity. In locations of low soil fertility, manure recycling and the

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introduction of leguminous forage into grain crop systems are more valuable. Grass-based

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rotation is also recommended to control soil erosion, especially on sloping land.20,46 Dairy

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feedlots near water courses near major urban populations often cause water quality

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deterioration and impacts to human health, especially on rainy days, and the FCICW is

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suitable for these areas to reduce water pollution.

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Economic feasibility. The cost-benefit analysis of dairy feedlots shows that

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transforming from a semi- to fully-coupled system increased the cost of manure treatment

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facilities and labor inputs for manure collection and storage, offsetting the benefits gained

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by selling manure and saving energy (Table S17), thus reducing its economic attractiveness.

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Although the decline in net profit is not substantial (a decrease of 2.4% from a semi- to

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fully-coupled system), feedlot owners are reluctant to improve manure management, and

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they illegally discharge wastes. As feed costs account for ~70% of the total cost of a dairy

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feedlot (Table S17), feedlot owners are more willing to invest in feed management, which

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directly links to milk yield and net profit. For feed crop farmers, reusing manure reduces

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the cost of chemical fertilizers: 20% of chemical fertilizer N is replaced by manure in a

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semi-coupled system, and 44% is replaced in a fully-coupled system (Table S18). However,

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the application of manure requires more labor than chemical fertilizer.13,23 The increased

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costs for manure transport and application are higher than chemical fertilizer savings in

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fully-coupled systems (Table S18) and thus constrain the recycling of manure, especially

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large volumes of liquid manure.

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Fortunately, with lower environmental externalities, fully-coupled systems justify the

340

provision of greater financial incentives to encourage expansion (Figure S13). In fact, for

341

the construction of biogas digesters on some dairy feedlots, owners can receive subsidies

342

from central and local governments, equivalent to 40-60% of the total construction costs.47

343

For CWs, although the construction and maintenance costs are high, most of the costs

344

should come from government subsidies considering the role of CWs in reducing regional

345

environmental pollution.48 To accelerate the reuse of animal waste, the Chinese government

346

has set a target that more than 95% of industrial feedlots will be equipped with waste

347

treatment facilities by 2020, and China issued the first guidance document on animal waste

348

treatment and utilization in June 2017.49 This document enhances the financial support for

349

feedlots with improved manure treatment facilities and for the organization of social

350

services to provide technical guidance and assistance. In addition, the Chinese government

17



351

is strengthening environmental regulations for the livestock sector.36,49 For crop growers,

352

forage-crop rotation is promoted by China’s “grain for forage” policy,50 which includes a

353

new information on the structure adjustment of China’s agriculture. Grass-crop or

354

forage-grain rotations not only contribute to the self-sufficiency of feed for ruminant

355

production but also improve the quality of the soil. In addition, redirecting the current

356

subsidies for the fertilizer industry towards manure application would promote manure

357

recycling and stabilize the use of mineral fertilizer to achieve the “Zero Fertilizer Growth

358

by 2020” goal.35 Under the support from a variety of policies, it is expected that the

359

fully-coupled systems will expand quickly in the near future.

360

Land requirement. The institutional policy whereby feedlot owners have right to use

361

neighboring farmlands is another major prerequisite. Our field survey showed that many

362

industrial dairy feedlots in China are in regions with enough farmlands for recycling animal

363

manure (see SI for details, Figure S14). However, most of these lands cannot be used for

364

recoupling due to the limitation of land-use rights for feedlot owners. This is different to

365

dairy farms in developed countries where vast areas of farmlands can be owned by a single

366

individual.13,51 China's land ownership dictates that Chinese farmers can only have land-use

367

rights but not the land ownership. The lands around the feedlots are usually dispersed to

368

many farmers, leading to low levels of per capita land availability. Fortunately, the Chinese

369

government has begun to address these land issues by improving land-use policies. Farmers

370

can rent or contract with other people through land transfer for land management. The

371

guidance document on animal waste treatment and utilization issued in June 2017 suggests

18


Page 18 of 36

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372

improving land-use policies for industrial feedlots, taking into account the land requirement

373

for manure management in overall land-use planning, and constructing new industrial

374

feedlots according to the supporting land area.49 These policies will contribute to the

375

recycling of animal manure. The alternative solution of not reducing the feedlot size is

376

meant to introduce land-saving technologies. For example, according to our calculations, a

377

dairy feedlot needs 0.14 ha of farmlands (or CWs) to support one head of dairy cow. If

378

recoupled with greenhouses (industrial farmlands equipped with plastic or glass cover) for

379

vegetable cultivation, which requires more fertilizer input per unit area due to the extended

380

cultivation season,34 the amount of land required would be only 0.02 ha per cow. In

381

addition, recoupling dairy feedlots with greenhouses is a solution to recycling animal

382

manure in cold regions and cold seasons.

383

Improvement potential of fully-coupled systems. Industrial dairy feedlots in China

384

contributed approximately 46% to the domestic milk production in 2011, and the

385

percentage is predicted to reach 85% by 2020 (Figure S15, S16). Total milk production will

386

increase by 12% from 2011 to 2020, while the total NH3 emissions and N discharge into

387

water show a slight decreasing trend due to a higher degree of industrialization assumed in

388

the BAU scenario. To produce one ton of milk, the industrial system with improved

389

production efficiency generates less environmental impacts than the non-industrial systems

390

(Figure S17). However, GHG emissions continue to increase from 2011 to 2020 in the

391

BAU scenario. If all Chinese industrial dairy feedlots were fully-coupled with industrial

392

farmlands by 2020 (Scenario 2), GHG and NH3 emissions and N discharge into water from

19



393

the entire milk production chain would decrease by 22%, 10%, and 28%, respectively,

394

compared with the BAU scenario (Figure 4). A fully-coupled system with CWs (Scenario 3)

395

would reduce GHG and NH3 emissions and N discharge into water by 30%, 25.7%, and

396

42%, respectively.

397

As all industrial feedlots face similar challenges in terms of handling excess liquid

398

waste, fully-coupling industrial feedlots with industrial farmlands is a viable solution to

399

reduce the environmental impacts of global milk production. Advanced technology

400

deployment and appropriate policy instruments will facilitate opportunities for sustainable

401

livestock production. We believe that the fully-coupled paradigms are not only applicable in

402

China but also can provide a model for other nations facing environmental pressures caused

403

by livestock industrialization.

404 405

ASSOCIATED CONTENT

406

Supplementary Information

407

The Supporting Information is available free of charge on the ACS Publications website.

408

Details on the data, methods, and model used for calculating the environmental impacts,

409

ecosystem services, and land use and supporting figures and tables as mentioned in the

410

text (PDF) are in the Supporting Information.

411 412

AUTHOR INFORMATION

413

Corresponding Author

20


Page 20 of 36

Page 21 of 36


414

* College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058,

415

PR China.

416

Tel & Fax: +86 571 8820 6466. E-mail: [email protected]

417

Notes

418

The authors declare no competing financial interests.

419 420

ACKNOWLEDGMENTS

421

We thank Y. Min, F. Mao, W. Yang and M. Mikkilä for their comments on an earlier version

422

of the manuscript or assistance during manuscript preparation, and C.C. Huang, C.B. Zhang,

423

S.Y. Li, Ri-e Bu, X.P. Ge, M. Chang, Y. Geng, Z.L. Qu, W.J. Han, R.H. Xu, C.D. Fang, B.

424

Luo, Z.Y. Zhao, K.X. Pan, C.C. Yu, M.M. Shi, K.D. Zhu and T. Zhou for assistance in the

425

field experiments. We thank J.X. Liu for consultation on dairy cow breeding. This work

426

was supported by the Natural Science Foundation of China (NSFC 31670329, 31470463,

427

31770434).

428 429

REFERENCES

430

(1) FAOStat: Food and Agriculture Data, Food and Agriculture Organization (FAO).

431

http://faostat3.fao.org/browse/Q/QL/E (accessed December 20, 2016)

432

(2) Alexandratos, N.; Bruinsma, J. World Agriculture Towards 2030/2050: The 2012

433

Revision. Food and Agriculture Organization of the United Nations: Rome 2012.

21



434

(3) Herrero, M.; Thornton, P. K.; Gerber, P.; Reid, R. S. Livestock, livelihoods and the

435

environment: understanding the trade-offs. Curr. Opin. Environ. Sustain. 2009, 1,111-120.

436

(4) Steinfeld, H.; Gerber, P.; Wassenaar, T. D.; Castel, V.; de Haan, C. Livestock's long

437

shadow: environmental issues and options. Food and Agriculture Organization (FAO),

438

2006.

439

(5) Bai, Z. H.; Ma, L.; Oenema, O.; Chen, Q.; Zhang, F. S. Nitrogen and phosphorus use

440

efficiencies in milk production in China. J. Environ. Qual. 2013, 42, 990-1001.

441

(6) Tilman, D.; Cassman, K. G.; Matson, P. A.; Naylor, R.; Polasky, S. Agricultural

442

sustainability and intensive production practices. Nature 2002, 418, 671-677.

443

(7) Aneja, V. P.; Schlesinger, W. H.; Erisman, J. W. Farming pollution. Nat. Geosci. 2008, 1,

444

409-411.

445

(8) Owen, J. J.; Silver, W. L. Greenhouse gas emissions from dairy manure management: a

446

review of field‐based studies. Global change boil. 2015, 21(2), 550-565.

447

(9) Naylor, R.; Steinfeld, H.; Falcon, W.; Galloway, J.; Smil, V.; Bradford, E.; Alder, J.;

448

Mooney, H. Losing the links between livestock and land. Science 2005, 310, 1621-1622.

449

(10) Stokstad, E. Ammonia pollution from farming may exact hefty health costs. Science

450

2014, 343(6168), 238-238.

451

(11) Wu, Y. Y.; Gu, B. J.; Erisman, J. W.; Reis, S.; Fang, Y. Y.; Lu, X. H.; Zhang, X. M.

452

PM2.5 pollution is substantially affected by ammonia emissions in China. Environ. Pollut.

453

2016, 218, 86-94.

454

(12) Hilimire, K. Integrated Crop/Livestock Agriculture in the United States: A Review. J.

22


Page 22 of 36

Page 23 of 36


455

Sustain. Agr. 2011, 35, 376-393.

456

(13) Russelle, M. P.; Entz, M. H.; Franzluebbers, A. J. Reconsidering integrated

457

crop-livestock systems in North America. Agron. J. 2007, 99, 325-334.

458

(14) Lemaire, G.; Franzluebbers, A.; Carvalho, P. C. D. F.; Dedieu, B. Integrated crop–

459

livestock systems: Strategies to achieve synergy between agricultural production and

460

environmental quality. Agr. Ecosyst. Environ. 2014, 190, 4-8.

461

(15) Ryschawy, J.; Choisis, N.; Choisis, J. P.; Joannon, A.; Gibon, A. Mixed crop-livestock

462

systems: an economic and environmental-friendly way of farming? Animal, 2012, 6,

463

1722-1730.

464

(16) Xia, L.; Lam, S. K.; Yan, X.; Chen, D. How does recycling of livestock manure in

465

agroecosystems affect crop productivity, reactive nitrogen losses, and soil carbon balance?

466

Environ. Sci. Technol. 2017, 51, 7450-7457.

467

(17) Franzluebbers, A. J. Integrated Crop–Livestock Systems in the Southeastern USA.

468

Agron. J. 2007, 99, 361-372.

469

(18) Sulc, R. M.; Tracy, B. F. Integrated Crop–Livestock Systems in the U.S. Corn Belt.

470

Agron. J. 2007, 99(2):431-446.

471

(19) Lemaire, G. Intensification of animal production from grassland and ecosystem

472

services: a trade-off. CAB Reviews 7, 2012, 12, 1-7.

473

(20) Lemaire, G.; Gastal, F.; Franzluebbers, A.; Chabbi, A. Grassland–cropping rotations:

474

An avenue for agricultural diversification to reconcile high production with environmental

475

quality. Environ. Manage. 2015, 56, 1065.

23



476

(21) Oenema, O.; Oudendag, D.; Velthof, G. L. Nutrient losses from manure management

477

in the European Union. Livest. Sci. 2007, 112(3), 261-272.

478

(22) Sutton, M. A.; Oenema, O.; Erisman, J. W.; Leip, A.; van Grinsven, H.; Winiwarter, W.

479

Too much of a good thing. Nature 2011, 472, 159-161.

480

(23) Ju, X.; Zhang, F.; Bao, X.; Römheld, V.; Roelcke, M. Utilization and management of

481

organic wastes in Chinese agriculture: Past, present and perspectives. Sci. China, Ser. C

482

2005, 48, 965-979.

483

(24) Bai, Z. H.; Li, X. X.; Lu, J.; Wang, X.; Velthof, G. L.; Chadwick, D.; Luo, J. F.;

484

Ledgard, S.; Wu, Z.G.; Jin, S. Q.; Oenema, O.; Ma, L.; Hu, C. S. Livestock Housing and

485

Manure Storage Need to Be Improved in China. Environ. Sci. Technol. 2017, 51,

486

8212-8214.

487

(25) Peyraud, J. L.; Taboada, M.; Delaby, L. Integrated crop and livestock systems in

488

Western Europe and South America: A review. Eur. J. Agron. 2014, 57, 31-42.

489

(26) Regan, J. T.; Marton, S.; Barrantes, O.; Ruane, E.; Hanegraaf, M.; Berland, J.;

490

Korevaar, H.; Pellerin, S.; Nesme, T. Does the recoupling of dairy and crop production via

491

cooperation between farms generate environmental benefits? A case-study approach in

492

Europe. Eur. J. Agron. 2017, 82, 342-356.

493

(27) Liu, D.; Ge, Y.; Chang, J.; Peng, C. H.; Gu, B. H.; Chan, G. YS.; Wu, X. F.

494

Constructed wetlands in China: recent developments and future challenges. Front. Ecol.

495

Environ. 2008, 7, 261-268.

24


Page 24 of 36

Page 25 of 36


496

(28) Liu, D.; Wu, X.; Chang, J.; Gu, B. J.; Min, Y.; Ge, Y., Shi, Y.; Peng, C. H.; Wu, J. G.

497

Constructed wetlands as biofuel production systems. Nat. Clim. Change 2012, 2, 190-194.

498

(29) Dunne, E. J.; Culleton, N.; O’Donovan, G.; Harrington, R.; Olsen, A. E. An integrated

499

constructed wetland to treat contaminants and nutrients from dairy farmyard dirty water.

500

Ecol. Eng. 2005, 24, 219-232.

501

(30) Knight, R. L.; Payne, V. W.; Borer, R. E.; Clarke, R. A.; Pries, J. H. Constructed

502

wetlands for livestock wastewater management. Ecol. Eng. 2000, 15, 41-55.

503

(31) Ndegwa, P. M.; Hristov, A. N.; Arogo, J.; Sheffield, R. E. A review of ammonia

504

emission mitigation techniques for concentrated animal feeding operations. Biosyst. Eng.

505

2008, 100(4), 453-469.

506

(32) Wang, Y.; Dong, H. M.; Zhu, Z. P.; Gerber, P. J.; Xin, H. W.; Smith, P.; Opio, C.;

507

Steinfeld, H.; and Chadwick, D. Mitigating greenhouse gas and ammonia emissions from

508

swine manure management: a system analysis. Environ. Sci. Technol. 2017, 51(8),

509

4503-4511.

510

(33) MA. Ecosystems and Human Well-being: Synthesis. World Resources Institute. Island

511

Press, Washington, DC. (Millennium Ecosystem Assessment) (2005).

512

(34) Chang, J.; Wu, X.; Liu, A. Q.; Wang, Y.; Xu, B.; Yang, W.; Meyerson, L. A.; Gu, B. J.;

513

Peng, C. H.; Ge, Y. Assessment of net ecosystem services of plastic greenhouse vegetable

514

cultivation in China. Ecol. Econ. 2011, 70, 740-748.

25



Page 26 of 36

515

(35) Ministry of Agriculture (MOA): “Zero growth of fertilizer and pesticide use” started.

516

http://www.gov.cn/xinwen/2015-03/18/content_2835617.htm

517

December 10, 2016)

518

(36) Ministry of Agriculture (MOA): Development Plan of China’s Dairy (2016-2020)

519

http://www.moa.gov.cn/govpublic/XMYS/201701/P020170109560926642126.ceb

520

Chinese, accessed February 10, 2017)

521

(37) Han, W. J.; Chang, J.; Fan, X.; Du, Y. Y.; Chang, S. X.; Zhang, C. B.; Ge, Y. Plant

522

species diversity impacts nitrogen removal and nitrous oxide emissions as much as carbon

523

addition in constructed wetland microcosms. Ecol. Eng. 2016, 93, 144-151.

524

(38) Gerber, P. J.; Henderson, B.; Makkar, H. P. S. Mitigation of greenhouse gas emissions

525

in livestock production: A review of technical options for non-CO2 emissions. Food and

526

Agriculture Organization of the United Nations, Rome, 2013.

527

(39) NY/T 2374-2013. Technical code of post-treatment of digested sludge and slurry from

528

biogas plant. Ministry of Agriculture of the People’s 891 Republic of China 2013.

529

(40) Erisman, J. W.; Bleeker, A.; Hensen, A.; Vermeulen, A. Agricultural air quality in

530

Europe and the future perspectives. Atmos. Environ. 2008, 42, 14, 3209-3217.

531

(41) Chen, D.; Sun, J.; Bai, M.; Dassanayake, K. B.; Denmead, O. T.; Hill, J. A new

532

cost-effective method to mitigate ammonia loss from intensive cattle feedlots: application

533

of lignite. Scientific reports 2015, 5, 16689.

26


(in

Chinese,

accessed

(in

Page 27 of 36

534


(42)

Dutch

dairy

cull

plan

agreed

by

EU.

535

http://www.fwi.co.uk/business/dutch-dairy-cull-plan-agreed-u.htm (accessed November 20,

536

2017)

537

(43) Kunrath, T. R.; Berranger, C. D.; Charrier, X.; Gastal, F.; Carvalho, P. C. D. F.;

538

Lemaire, G.; Emile, J. C. How much do sod-based rotations reduce nitrate leaching in a

539

cereal cropping system? Agr. Water Manage. 2015, 150:46-56.

540

(44) Ballesta, A.; Lloveras, J. Nitrogen replacement value of alfalfa to corn and wheat

541

under irrigated Mediterranean conditions. Span. J. Agric. Res. 2010, 8, 159-169.

542

(45) Soussana, J. F.; Lemaire, G. Coupling carbon and nitrogen cycles for environmentally

543

sustainable intensification of grasslands and crop-livestock systems. Agr. Ecosyst. Environ.

544

2014, 190(2):9-17.

545

(46) Jankauskas, B.; Jankauskiene, G. Erosion-preventive crop rotations for landscape

546

ecological stability in upland regions of Lithuania. Agr. Ecosyst. Environ. 2003, 95,

547

129-142.

548

(47) Jiang, X.; Sommer, S. G.; Christensen, K. V. A review of the biogas industry in China.

549

Energ. Policy 2011, 39, 6073-6081.

550

(48) Gu, B. J.; Fan, L. C.; Ying, Z. C.; Xu, Q. S.; Luo, W. D.; Ge, Y.; Scott, S. and Chang, J.

551

Socioeconomic constraints on the technological choices in rural sewage treatment. Environ.

552

Sci. Pollut. R. 2016, 23(20):1-8.

553

(49) The General Office of the State Council. Opinions of speeding up the utilization of

554

livestock

and

poultry

27


waste.


Page 28 of 36

555

http://www.gov.cn/zhengce/content/2017-06/12/content_5201790.htm

556

accessed June 20, 2017)

557

(50) Ministry of Agriculture (MOA). The Ministry of Agriculture issued the

558

"implementation

559

http://www.moa.gov.cn/zwllm/tzgg/tz/201705/P020170527591691316913.ceb (in Chinese,

560

accessed August 20, 2017)

561

(51) Bell, L. W.; Moore, A. D. Integrated crop–livestock systems in Australian agriculture:

562

Trends, drivers and implications. Agr. Syst. 2012, 111, 1-12.

plan

of

grain

563

28


(in

for

Chinese,

forage".

Page 29 of 36

564


Figure captions

565 566

Figure 1. Flow of nitrogen in the entire milk production chain. a. the industrial feedlot

567

is semi-coupled with farmlands; b. the industrial feedlot is fully-coupled with industrial

568

farmlands (FCIIC); c. the industrial feedlot is fully-coupled with constructed wetlands

569

(FCICW). Arrows represent N flow: blue- feed production process; orange- feed processing;

570

gray- dairy cow rearing (S: solid manure, L: liquid manure); yellow- milk processing;

571

black- N loss to environment. Values are kilograms of N in the production of one ton of

572

milk.

573 574

Figure 2. Intensities of GHGs and NH3 emissions and N discharge into water in milk

575

production systems. N2O, CH4, CO2, total GHG, and NH3 are shown in a-e, and N

576

discharge is shown in f. Blue- feed crop production process; orange- feed processing; gray-

577

dairy cow rearing; yellow- milk processing. Bars are standard errors of the entire chain

578

including the four processes. Different letters denote significant differences among the

579

three coupling modes. FCIIC: fully-coupled industrial dairy feedlots with industrial

580

farmlands. FCICW: fully-coupled industrial dairy feedlots with constructed wetlands.

581 582

Figure 3. Gaseous emissions from dairy wastes management. a-c, daily emission rates

583

(normalized) of N2O, CH4, and NH3. The regression analyses between gas emissions and

584

exposure time of solid or liquid manure to the air are displayed as follows: for solid manure,

29



585

N2O = -0.008x2 + 0.480x + 38.578, R2 = 0.10, P < 0.001; CH4 = 0.001x2 - 0.435x + 42.266,

586

R2 = 0.11, P < 0.001; NH3 = 79.229 × e -0.064x, R2 = 0.14, P < 0.001; for liquid manure, N2O

587

= 0.017x2 + 0.956x -13.241, R2 = 0.46, P = 0.085; CH4 = -0.027x2 + 2.559x - 7.884, R2 =

588

0.41, P < 0.001; NH3 = 58.705 × e -0.067x, R2 = 0.12, P = 0.008. d-f, cumulative emissions of

589

N2O, CH4, and NH3, dashed lines indicate the half loss point for each gas.

590 591

Figure 4. Milk production and its environmental impacts from 2002 to 2020 in China.

592

Milk production is shown in a, the total GHG and NH3 emissions and N discharge into

593

water are shown in b-d. Red dots represent milk production and environmental impacts

594

from 2002 to 2011; black triangles represent the scenario for semi-coupled systems to

595

continue to 2020; blue dots represent fully-coupled systems of all industrial dairy feedlots

596

with industrial farmlands (FCIIC); and green dots represent fully-coupled systems of all

597

industrial dairy feedlots with constructed wetlands (FCICW).

598 599 600

30


Page 30 of 36

Page 31 of 36

601


Figure 1

602

603

604 605 606

31



607

Figure 2

608

609 610

32


Page 32 of 36

Page 33 of 36

611


Figure 3

612

613 614

33



615 616

Figure 4

617 618

34


Page 34 of 36

Page 35 of 36


619

Table 1. Ecosystem services provided by industrial milk production systems under

620

four coupling modes (USD ha-1 yr-1) Item

Semi-coupled

FCIIC

FCICW

FCIIC-R

1144.8±17.4

1112.1±16.9

1098.5±16.7

1143.9±17.4

Water saving

0.0

4.0±0.1

4.0±0.1

4.0±0.1

Water regulation

0.0

0.0

50.6±0.8

0.0

GHG emissions

-925.6±17.6

-650.6±14.6

-542.4±11.5

-559.6±14.4

NH3 emissions

-815.5±16.1

-709.8±15.6

-550.2±11.0

-700.8±15.7

N discharge into water

-67.2±1.5

-45.4±1.5

-31.9±0.9

-32.5±1.2

-663.3±21.3

-289.7±19.1

28.6±12.9

-145.1±18.8

Provisioning services Fresh milk Regulating services

Net ecosystem services 621

An industrial milk production system includes two directly coupled components: a dairy

622

feedlot and farmlands (or CWs). FCIIC: fully-coupled industrial dairy feedlots with

623

industrial farmlands, FCICW: fully-coupled industrial dairy feedlots with constructed

624

wetlands. FCIIC-R: fully-coupled industrial dairy feedlots with forage-crop rotation. Values

625

are mean ± SE (n = 108).

626

35



627

An art piece as a visual abstract for the Table of Contents

628

629

36


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Recoupling Industrial Dairy Feedlots and Industrial Farmlands

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