Recoupling Industrial Dairy Feedlots and Industrial Farmlands

Mar 8, 2018 - Our approach provides a template for mitigating environmental impacts from livestock production without sacrificing milk production. ...
2 downloads 8 Views 1MB Size
Subscriber access provided by - Access paid by the | UCSB Libraries

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

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 36

Environmental Science & Technology

1

Recoupling industrial dairy feedlots and industrial farmlands mitigates the

2

environmental impacts of milk production in China

3 4

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

5

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

6 7



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

8



Zhejiang Provincial Economic Information Center (Zhejiang Center for Climate Change

9

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

10

§

11

Nanjing 210042, PR China

12

||

13

Canada

14

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

15

02881, USA

16

#

17

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

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

1

ACS Paragon Plus Environment

Environmental Science & Technology

18

ABSTRACT

19

Dairy production is becoming more industrialized globally, especially in developing

20

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

21

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

22

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

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

provides a template for mitigating environmental impacts from livestock production

34

without sacrificing milk production.

35

2

ACS Paragon Plus Environment

Page 2 of 36

Page 3 of 36

36

Environmental Science & Technology

INTRODUCTION

37

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

38

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

39

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

40

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

41

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

42

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

43

Manure management for industrial livestock production results in a substantial contribution

44

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

45

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

46

industrialization that produces more dairy products with less environmental and human

47

health impacts is a challenge.

48

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

49

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

50

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

51

specialized feedlots and excessive mineral fertilizer application on farmlands are severe

52

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

53

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

54

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

55

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

56

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

3

ACS Paragon Plus Environment

Environmental Science & Technology

57

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

58

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

59

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

60

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

61

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

62

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

63

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

64

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

65

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

66

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

67

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

68

comprehensive assessments of the environmental performance of recoupling and relevant

69

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

70

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

71

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

72

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

73

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

74

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

75

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

76

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

77

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

4

ACS Paragon Plus Environment

Page 4 of 36

Page 5 of 36

Environmental Science & Technology

78

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

79

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

80

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

81

the comprehensive understanding and spread of recoupling.

82

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

83

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

84

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

85

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

86

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

87

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

88

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

89

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

90

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

91

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

92

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

93

and economic performances, ecosystem services under different coupling modes are

94

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

95

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

96 97 98

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

5

ACS Paragon Plus Environment

Environmental Science & Technology

99

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

100

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

101

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

102

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

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

Information (SI).

111

Industrial dairy production systems. Two coupling degrees are distinguished

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

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

6

ACS Paragon Plus Environment

Page 6 of 36

Page 7 of 36

Environmental Science & Technology

120

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

121

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

122

S2).

123

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

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

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

132

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

133

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

134

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

135

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

136

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

137

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

138

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

139

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

140

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

7

ACS Paragon Plus Environment

Environmental Science & Technology

141

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

142

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

143

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

144

band spreading for liquid manure.32

145

Calculation of nitrogen flux and environmental impacts. We calculated the

146

parameters using the STELLA graphic programming system (High Performance System

147

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

148

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

149

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

150

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

151

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

152

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

153

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

154

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

155

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

156

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

157

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

158

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

159

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

160

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

161

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

8

ACS Paragon Plus Environment

Page 8 of 36

Page 9 of 36

Environmental Science & Technology

162

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

163

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

164

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

165

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

166

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

167

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

168

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

169

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

170

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

171

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

172

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

173

services than the coupling mode.

174

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

175

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

176

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

177

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

178

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

179

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

180

summed as “other” in Tables S16 and S17.

181

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

182

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

9

ACS Paragon Plus Environment

Environmental Science & Technology

183

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

184

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

185

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

186

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

187

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

188

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

189

dairy feedlots are fully-coupled with CWs.

190

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

191

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

192

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

193

(see SI for details).

194 195

RESULTS AND DISCUSSION

196

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

197

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

198

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

199

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

200

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

201

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

202

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

203

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

10

ACS Paragon Plus Environment

Page 10 of 36

Page 11 of 36

Environmental Science & Technology

204

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

205

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

206

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

207

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

208

CWs for plant growth, further reducing N loss.

209

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

210

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

211

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

212

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

213

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

214

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

215

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

216

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

217

hydraulic pattern or28 adding carbon or plant assemblages.37

218

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

219

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

220

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

221

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

222

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

223

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

224

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

11

ACS Paragon Plus Environment

Environmental Science & Technology

225 226

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

227

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

228

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

229

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

230

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

231

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

232

of milk.

233

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

234

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

235

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

236

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

237

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

238

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

239

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

240

needed for developed countries to further reduce gaseous pollutants.

241

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

242

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

243

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

244

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

245

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

12

ACS Paragon Plus Environment

Page 12 of 36

Page 13 of 36

Environmental Science & Technology

246

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

247

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

248

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

249

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

250

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

251

artificial management, appropriate structures, and physicochemical environment regulation.

252

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

253

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

254

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

255

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

256

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

257

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

258

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

259

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

260

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

261

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

262

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

263

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

264

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

265

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

266

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

13

ACS Paragon Plus Environment

Environmental Science & Technology

267

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

268

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

269

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

270

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

271

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

272

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

273

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

274

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

275

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

276

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

277

groundwater pollution caused by phosphate as well as nitrate leaching.

278

Ecosystem services. Synthesizing environmental performance (regulating services

279

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

280

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

281

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

282

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

283

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

284

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

285

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

286

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

287

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

14

ACS Paragon Plus Environment

Page 14 of 36

Page 15 of 36

Environmental Science & Technology

288

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

289

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

290

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

291

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

292

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

293

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

294

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

295

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

296

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

297

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

298

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

299

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

300

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

301

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

302

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

303

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

304

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

305

fully recycling manure with these agronomic services provided by converting from

306

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

307

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

308

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

15

ACS Paragon Plus Environment

Environmental Science & Technology

309

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

310

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

311

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

312

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

313

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

314

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

315

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

316

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

317

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

318

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

319

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

320

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

321

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

322

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

323

suitable for these areas to reduce water pollution.

324

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

325

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

326

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

327

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

328

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

329

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

16

ACS Paragon Plus Environment

Page 16 of 36

Page 17 of 36

Environmental Science & Technology

330

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

331

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

332

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

333

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

334

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

335

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

336

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

337

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

338

large volumes of liquid manure.

339

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

Page 18 of 36

Page 19 of 36

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

Page 20 of 36

Page 21 of 36

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

Page 22 of 36

Page 23 of 36

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

Page 24 of 36

Page 25 of 36

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

(in

Chinese,

accessed

(in

Page 27 of 36

534

Environmental Science & Technology

(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

ACS Paragon Plus Environment

waste.

Environmental Science & Technology

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

ACS Paragon Plus Environment

(in

for

Chinese,

forage".

Page 29 of 36

564

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

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

ACS Paragon Plus Environment

Page 30 of 36

Page 31 of 36

601

Environmental Science & Technology

Figure 1

602

603

604 605 606

31

ACS Paragon Plus Environment

Environmental Science & Technology

607

Figure 2

608

609 610

32

ACS Paragon Plus Environment

Page 32 of 36

Page 33 of 36

611

Environmental Science & Technology

Figure 3

612

613 614

33

ACS Paragon Plus Environment

Environmental Science & Technology

615 616

Figure 4

617 618

34

ACS Paragon Plus Environment

Page 34 of 36

Page 35 of 36

Environmental Science & Technology

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

ACS Paragon Plus Environment

Environmental Science & Technology

627

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

628

629

36

ACS Paragon Plus Environment

Page 36 of 36