3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

THE PRELIMINARY STUDY ON ENHANCEMENT STRATEGY FOR WATER QUALITY MANAGEMENT IN XILUO IRRIGATION AREA OF

Ke-Chun Lin1, Ying-Chun Lin2, Ching-Ru Tang2, Chong-Yuan Lin2 and Pi-Hui Suzi Chang3

ABSTRACT

Yunlin County, known for its valuable agriculture and animal husbandry, is located at the south-central part of western Taiwan. Due to the geography, there is not enough surface runoff for irrigation purposes. Alternatively, the scheme of regional drainage reused for irrigation (RDRI) has been adopted by Taiwan Yunlin Irrigation Association (Yunlin IA) within certain irrigation areas, such as the Xiluo irrigation area, but some degradation of irrigation water quality occasionally happens. Aims of this study were (1) to understand how irrigation water quality was affected by RDRI, and (2) to propose enhancement strategies for Yunlin IA improving the irrigation water quality in the Xiluo irrigation area including the work-stations of Xiluo, Yinxi and Dayi. The affected areas of RDRI were accounted for 18.7% in Xiluo work-station, 31.1% in Yinxi work-station, and 100% in Dayi work-station, which was considered as the area seriously facing the problem of irrigation water quality deterioration. According to the industrial distribution in , animal waste could be the most influential sources polluting irrigation water. Since more than 80% of the livestock ranches in the Xiluo irrigation area were swine ranches, and many of them seemed not dealing with animal waste properly, the main pollution source might be the disposal of animal waste without appropriate pre-treatment. In conclusion, Yunlin IA should enhance the management on the discharge of animal husbandry waste via increasing waste pre- treatment, raising frequency of monitoring irrigation water quality, and cleaning irrigation ditch sediment while RDRI is applied. Along with the act of Taiwan Environmental Protection Administration on “livestock’s wastewater and solid waste recycling into the surrounding rural soils” started from 2017, co-operation between the livestock ranches and the surrounding agricultural land was strongly recommended to effectively promote the reuse of livestock waste and encourage farmers to practice recycling agriculture.

Keywords: Regional drainage reused for irrigation (RDRI), Animal husbandry, Livestock waste, Swine ranch, Manure, Wastewater, Recycling agriculture

1. INTRODUCTION

Yunlin County, located in the south-central part of western Taiwan, has an annual production value of agricultural commodities up to $2.6 billion, including$1.3 billion from crop farming and $1.1billion from animal husbandry (National Statistics, 2017). The total cultivated land area of Yunlin County is around 78,681 hectares, including 63,577 hectares of irrigation area managed by Taiwan Yunlin Irrigation Association (Yunlin IA) (Agricultural Statistics Yearbook, 2017; Taiwan Joint Irrigation Association,

1 Research Division III, Taiwan Research Institute on Water Resources and Agriculture (TRIWRA).19F, No.27-8, Sec. 2, Zhongzheng E. Rd., Tamsui Dist., New Taipei 251, Taiwan; E-mail: [email protected] 2 Irrigation Management Division, Irrigation and Drainage Section, Taiwan Yunlin Irrigation Association (Yunlin IA). 5F, No. 2, Xinghua St., City, Yunlin County 640, Taiwan; E-mail: [email protected] 3 Research Division III, Taiwan Research Institute on Water Resources and Agriculture (TRIWRA). 19F, No.27-8, Sec. 2, Zhongzheng E. Rd., Tamsui Dist., New Taipei 251, Taiwan; E-mail: [email protected]

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

2016).Because Yunlin County has long been one of the main sources for agricultural products in Taiwan, the quality of irrigation water supplied by Yunlin IA is supposed to be important to guard food safety and human health. Yunlin IA has already developed a mechanism to monitor and quickly respond to any pollution incident happening in irrigation water. The mechanism includes a regular monitoring network on water sources and specific sites along the irrigation ditches (Irrigation Water Quality Management Guidelines, 2017). Moreover, before any non-polluting waste water can be discharged into a ditch managed by Yunlin IA, a thorough application process must be completed and then approved (Agricultural Irrigation Water Quality Protection Act, 2013). During the period of discharging with permission, the discharged wastewater will be regularly checked by Yunlin IA in order to confirm that all standards of irrigation water quality have been complied with (Guidelines of Irrigation Water Quality Monitoring and Evaluation, 2017).These are good strategies to avoid most pollution incidents seriously affecting irrigation water quality.

Due to the geographic conditions of Yunlin County, it is difficult for Yunlin IA to collect enough surface runoff for irrigation purposes. In order to meet with the requirement of irrigation, Yunlin IA applies the scheme of regional drainage reused for irrigation (RDRI) in certain irrigation areas, such as the Xiluo irrigation area, which is one of the major cultivated land areas in Yunlin County. Nevertheless, there are approximately 1.5 million swine as livestock in Yunlin County (Quantity Report of Swine in Taiwan, 2018), and in the Xiluo irrigation area, more than 80% of the livestock ranches are swine ranches (Registration and Management System of Livestock Ranches, 2019). As animal husbandry is one of the main sources of agricultural waste, both in water and solid types, the swine ranches have been considered to discharge an extremely large amount of waste into environment (The Green National Income Account, 2017).Although many of livestock ranches in the Xiluo irrigation area discharge their effluent into regional drainages rather than the ditches managed by Yunlin IA, the waste would still affect the downstream irrigation water quality and annoy the nearby residents (Gerendáset al., 1997). The risk of degrading irrigation water quality would be increased by RDRI. According to Yunlin IA’s long-term monitoring data of irrigation water quality, the Xiluo irrigation area has been one of the seriously influenced areas by RDRI. With the intention of clarifying the potential pollution sources and evaluating the influential level of RDRI in the Xiluo irrigation area, this study was carried out.

The Xiluo irrigation area investigated in this study was composed of three work- stations including Xiluo, Yinxi and Dayi. Aims of this study were (1) to clarify how irrigation water quality was affected by RDRI, and (2) to propose enhancement strategies for Yunlin IA improving the irrigation water quality in the Xiluo irrigation area. Firstly, the area influenced by RDRI in the Xiluo irrigation area was evaluated by work-station. Secondly, the industrial distribution in the Xiluo irrigation area was analysed by industrial type. Thirdly, a series of sediment in Yunlin IA’s ditches was sampled and the heavy metals of arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu), chromium (Cr) and nickel (Ni) were examined to verify whether livestock waste causing degradation of irrigation water in the Xiluo irrigation area. Lastly, swine ranches within the Xiluo irrigation area were systematically selected and a questionnaire survey was conducted to give an overall picture of the on-site waste management there. From the results of this study, comprehensive enhancement strategies would be provided to improve irrigation water quality of RDRI in the Xiluo irrigation area. Hopefully, these enhancement strategies could also be applied to other areas of Yunlin I Ain the future.

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

2. METHODS

2.1 Analyses of irrigation Water Quality

A data set of five-year (from 2013 to 2017) monitoring of irrigation water quality in the Xiluo irrigation area, which included the work-stations of Xiluo, Yinxi and Dayi, was analysed. There were 209 monitoring points and 4,749 monitoring data of irrigation water indicators including water temperature (WT), pH value and electrical conductivity (EC).In this study, irrigation water quality monitoring data of Yunlin IA in 2013 and 2017 were screened out and calculated for annual averages of WT, pH and EC by work-station. The averages of each indicator in 2013 and 2017 were respectively shown on maps of the Xiluo irrigation area using the software of QGIS 2.18.13 (QGIS Development Team, 2016) and investigated changes in each work- station.

2.2 Analyses of Potential Pollution Sources

According to the regulation in Taiwan, it is necessary to be approved by Irrigation Associations before any non-polluting wastewater can be discharged into a ditch managed by Irrigation Associations (Agricultural Irrigation Water Quality Protection Act, 2013). From the quarterly report updated in July 2018, there were161 dischargers allowed to discharge into the ditches in the Xiluo irrigation area. The register of industrial type” (i.e. manufacture, livestock ranch and domestic sewage) of these dischargers were analysed. In order to diagnose any potential access and pathway of pollution, the locations of the dischargers were shown on a map of the Xiluo irrigation area using the software of QGIS 2.18.13(QGIS Development Team, 2016).

2.3 Sampling of Sediment in The Irrigation and Drainage Ditches

Due to the animal husbandry and livestock ranches could directly/indirectly discharge wastewater into neighbouring irrigation or drainage ditches managed by Yunlin IA, a series of sediment in ditches was sampled and analysed to serve as evidence of the influence of RDRI. 10 of the sampling sites either conducted RDRI or located along the main irrigation and drainage ditches in the Xiluo irrigation area were chosen:Xiluo drainage ditch (1M), Xinshe irrigation ditch (2M), Dinnan irrigation ditch (3M), Dayilun drainage ditch (4M), Dazhuang main irrigation ditch (5M), Xinzhuangzi main drainage ditch (6M), Central drainage ditch (7M), Bajiating main drainage ditch (8M), Nandayi main drainage ditch (9M) and main drainage ditch- Xindian irrigation branch (10M). 0.5-0.6 g of dried sample was digested by hydrochloric acid and analysed for heavy metals of As, Hg, Pb, Cd, Zn, Cu, Cr and Ni using an ICP-MS (NIEA S310.64B, NIEA M317.04B, NIEA M353.02C, Environmental Protection Administration, Executive Yuan, Taiwan).

2.4 Surveys of SWINE WASTE DISPOSAL

As more than 80% of the livestock ranches in the Xiluo irrigation area were swine ranches, detail information of these swine ranches was searched via the Registration and Management System of Livestock Ranches(http://aris.coa.gov.tw/,Council of Agriculture, Executive Yuan, Taiwan).Followed by comparing with the dischargers approved by Yunlin IA in the quarterly report updated in July 2018, 17 of small- medium sized swine ranches were matched .A questionnaire with multiple choice and open-ended questions was designed and applied to conduct interviews with the 17 swine ranches (Case et al., 2017; Houaet al., 2018). The results would be helpful to learn the real situation of swine waste disposal in the Xiluo Irrigation area.

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

3. RESULTS AND DISCUSSION

3.1 Analyses of Irrigation Water Quality

Yunlin IA has well managed the irrigation water quality by regularly monitoring water quality indicators, such as WT, pH and EC, in the irrigation and drainage ditchesevery two months. In this study, WT and pH did not have significant difference between 2013 and 2017 in each work-station in the Xiluo Irrigation area (data not shown). On contrast, by comparing annual EC averages between 2013 and 2017, varied trends in the three work-stations are shown in Figure 1 (a) and (b).EC is one of the most useful indicators of water quality measuring water’s capability to pass electrical flow. EC can directly relate to the concentration of ions in the water.

Therefore, the EC of Yinxiwork-station became higherand exceeded the irrigation water standard of 750 μS/cm in 2017 indicating that the irrigation water was getting worse there for some reason. In order to find out how the irrigation water quality might be affected by pollution, such as industrial wastewater discharge, urban domestic sewage release or animal husbandry wastewater intervention, potential pollution sources and industrial types were analysed in the next step.

Figure 1. Annual averages of electrical conductivity (EC)of the three work-stations (i.e.Xiluo, Yinxi and Dayi) in the Xiluo Irrigation area in (a) 2013 and (b) 2017 respectively. EC between 450-600 μS/cm represented in yellow, between 600-750 μS/cm represented in orange, and higher than 750 μS/cm represented in red.

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

3.2 Analyses of Potential Pollution Sources

The irrigation water source of the Xiluo irrigation area, which includes Xiluo, Yinxi and Dayi work-stations, comes from . Zhuoshui River mainly irrigates farmland of Xiluo and Yinxi work-stations via Luchangke irrigation ditch and Yinxi irrigation ditch respectively. However, due to Dayi work-station located in relatively downstream of the Xiluo irrigation area, water from Dayilun regional drainage must be used to meet with irrigation purposes. Overall irrigation water sources of the Xiluo irrigation area were listed in Table 1.

The scheme of RDRI was generally adopted in the Xiluo irrigation area. The areas of RDRI were accounted for about 190 hectares in Xiluo work-station (18.7%), about 413 hectares in Yinxi work-station (31.1%) and about 1,530 hectares in Dayi work- station (100%) (Table 1).Dayi work-station was considered as the most easily affected zone of Yunlin IA irrigation areas facing the problem of irrigation water quality deterioration. According to the previous study (Giorgi and Malacalza, 2002), water quality is significantly affected by industrial wastewater discharge, thus the industrial types of dischargers and potential pollution sources in the Xiluo irrigation area were analysed.

In the Xiluo irrigation area, there were total of 150-livestock-ranch and 11-domestic- sewage dischargers, which had been approved by Yunlin IA to discharge wastewater into ditches managed by Yunlin IA. No approved manufacture discharger in this area indicated that heavy metals should not be the main problem in the Xiluo irrigation area; however, a large amount of animal husbandry might discharge wastewater contain ingammonia-nitrogen (NH3-N), hydrogen sulphide (H2S), Cu and Zn, and gradually affect irrigation water quality in the Xiluo irrigation area (Nakayama and Bucks, 1991; Liouet al., 2004; Arora et al., 2008).

Table 1. Irrigation water sources of the Xiluo irrigation area

Work- RDRI % of total Irrigation water source Irrigated area (ha) station conducted irrigated area Luchangke irrigation ditch - 591.3 57.8 Xinshe irrigation ditch - 190.2 18.6 Xiluo Dinnan irrigation ditch - 49.8 4.9 Xiluo drainage ditch yes 191.1 18.7 Yinxi irrigation ditch - 431.8 32.6 Hopaoyu irrigation ditch - 481.3 36.3 Yinxi Shekou drainage ditch yes 151.1 11.4 Xinzhuangzi main drainage yes 261.6 19.8 ditch Dazhuang main irrigation yes 528.7 34.5 ditch* Dayilun main irrigation ditch* yes 840.4 54.9 Dayi Central drainage ditch yes 64.7 4.2 Tianwei main drainage ditch- yes 96.5 6.3 Xindian irrigation branch

* The irrigation water source of Dazhuang main irrigation ditch and Dayilun main irrigation ditch comes from Dayilun main drainage ditch, so RDRI are conducted.

The locations of livestock ranches and irrigation/drainage ditches in the Xiluo irrigation area were graphed, and it was helpful to learn more detail about where the potential access and pathwayof pollution were (Figure 2). The potential pollution sources in the Xiluo Irrigation area might be caused by a large amount of waste water discharged from animal husbandry into the drainage ditches of Xinzhuangzi, Xiluo,

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41

Shekou and Dayilun,managed by Yunlin IA. Through direct or indirect way, these drainage ditches might converge into certain regional drainages. When these regional drainages served as irrigation water sources and reused for irrigating downstream in the Xiluo irrigation area, it was likely to result in degradation of irrigation water quality and deterioration of agricultural environment.

Figure 2. Locations of sediment sampling points (green points), approved dischargers (orange points), irrigation ditches (red lines), drainage ditches (blue lines) and regional drainages (brown lines) in the Xiluo irrigation area. The approved dischargers were composed of the industrial types of animal husbandry and domestic sewage.

3.3 Sampling of Sediment in the Irrigation and Drainage Ditches

Wastewater discharged from animal husbandry usually contains certain heavy metals, such as Cu and Zn, and these heavy metals are likely to accumulate in the sediment and lead to degradation of irrigation water quality (Arora et al., 2008). In this study, sampling a series of sediment in the irrigation and drainage ditches was conducted, and the concentrations of As, Hg, Pb, Cd, Zn, Cu, Cr and Ni were analysed. Due to the results of As, Hg, Pb, Cd, Cr and Ni did not exceed the sediment standards (data not shown), only the results of Cu and Zn were shown in Table 2. The concentrations of Cuin Central drainage ditch (7M), Bajiating main drainage ditch (8M) and Tianwei main drainage ditch- Xindian irrigation branch (10M) were 58.8 mg/kg, 98.0 mg/kg and 67.4 mg/kg respectively, exceeding the lower limit of sediment quality standardof 50 mg/kg (Sediment Standard of Assessment and Management, 2012). The result of Bajiating main drainage ditch (8M) had the highest concentration of Cu in the sediment, which was consistent with the location of Bajiating main drainage ditch at the actual downstream of the Xiluo irrigation area.

Zn could also be evidence of wastewater discharge from animal husbandry. The concentrations of Zn in Dayilun drainage ditch (4M), Dazhuang main irrigation ditch (5M), Central drainage ditch (7M), Nandayi main drainage ditch (9M) and Tianwei main drainage ditch- Xindian irrigation branch (10M) were 155 mg/kg, 141 mg/kg, 352 mg/kg, 157 mg/kg and 372 mg/kg respectively, exceeding the lower limit of sediment quality standard of 140 mg/kg (Sediment Standard of Assessment and Management, 2012). It was not surprising that the Zn concentration of Bajiating main drainage ditch (8M)was up to 480 mg/kg, which was the highest one among the 10 sampling points

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 and higher than the upper limit of sediment quality standard of 384 mg/kg (Sediment Standard of Assessment and Management, 2012). These results corresponded to the assumption that the confluence of livestock wastewater from irrigation/drainage ditches and regional drainages resulted inirrigation water quality degradation and heavy metal accumulation in the sediment in the Xiluo irrigation area.

Table 2. Concentrations of copper (Cu) and zinc (Zn) in the ditch sediment in the Xiluo irrigation area. The lower and upper limits of sediment standards of Cuare 50 mg/kg and 157 mg/kg;ofZnare 140 mg/kg and 384 mg/kg. Results exceeding the lower limit of sediment standard were shown in blue-bold, and exceeding the upper limit of sediment standard were shown in red-bold.

Sampling points Cu (mg/kg) Zn (mg/kg) Lower limit of sediment standard 50 140 Upper limit of sediment standard 157 384 Xiluo drainage ditch (1M) 25.0 118 Xinshe irrigation ditch (2M) 21.8 124 Dinnan irrigation ditch (3M) 28.1 136 Dayilun drainage ditch (4M) 44.2 155 Dazhuang main irrigation ditch (5M) 33.2 141 Xinzhuangzi main drainage ditch (6M) 25.7 107 Central drainage ditch (7M) 58.8 352 Bajiating main drainage ditch (8M) 98.0 480 Nandayi main drainage ditch (9M) 39.6 157 Tianwei main drainage ditch- Xindian irrigation branch (10M) 67.4 372

3.4 Surveys of Swine Waste Disposal

Due to the swine industry in Taiwan went on high alert following the outbreak of African swine fever in China in August 2018, most swine ranches rejected any visitand interview in the first place. Therefore, only eight out of 17 questionnaires were completed in this study. According to the results, all swine ranches had been equipped with waste treatment facilities by law, but most of them did not operate properly.

For example, it was normal to find that a swine ranch exposed swine manure in an open-air situation (Figure 3), which might cause manure juice leaking into underground or neighbouring ditches during the composting process. On the other hand, some small-molecular nutrients might release into the air or leach with the rain. Furthermore, after separating the wastewater from solid waste of swine manure, most swine ranches directly discharged the wastewater into the ditches and left the solid waste in a pile to compost without enough amount of material to gather heat, without regular turnover to supply oxygen, or without any other substance to adjust the C/N ratio. If the compost did not become thoroughly decomposed before use, it might spread pathogens and weed seeds into the farmland, or cause unbalanced nutrition of crops (Houaet al., 2018).

4. CONCLUSIONS

By analysing the long-term monitoring data of irrigation water quality in the irrigation areas of Yunlin IAin Yunlin County, a trend of degrading in irrigation water quality in the Xiluo irrigation area was found. In this study, three work-stations of Xiluo, Yinxi and Dayiin the Xiluo irrigation area were investigated. Because of the geographic conditions, it is difficult for Yunlin IA to collect enough surface runoff to meet with irrigation requirement. Alternatively, the scheme of RDRI has been adopted in certain

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 irrigation areas. The Xiluo irrigation area is one of the examples. According to the water sources in the Xiluo irrigation area, the work-stations investigated in this study were more or less affected by RDRI. With no surprising, the degradation of EC in Yinxi work-station was considered that a round one third of the irrigated farmland in Yinxi work-station was supplied by RDRI. On the other hand, the whole irrigated farmland in Dayi work-station was supplied by RDRI, where was with the high risk of being influenced by RDRI and facing the problem of irrigation water quality deterioration.

Figure 3. The animal manure of a swine ranch in the Xiluo irrigation area was exposed in an open-air site without appropriate pre-treatment.

The approved discharges in the Xiluo irrigation area was composed ofa lot of livestock ranches and a few domestic sewages. The large number of livestock ranches might discharge large amount of wastewater containing NH3-N, H2S, Cu and Zn. Even though the wastewater was normally allowed to discharge into drainage ditches, through direct or indirect way, these drainage ditches might converge into certain regional drainages. When these regional drainages served as irrigation water sources and reused for irrigating downstream of the Xiluo irrigation area, it was likely to result in degradation of irrigation water quality and deterioration of agricultural environment.

Some contaminants, such as heavy metals, would accumulate in the sediment and interfere in agricultural environment. A series of sediment in the irrigation/drainage ditches managed by Yunlin IA was sampled and the concentrations of As, Hg, Pb, Cd, Zn, Cu, Cr and Ni were analysed. The results showed that concentrations of Cu and Zn in certain ditches, which were relatively located at the downstream of the Xiluo irrigation area, had exceeded the sediment standards. The high concentrations of Cu and Zn in the sediment could confirm that the irrigation water quality was affected by animal husbandry. Without appropriate management and treatment to the wastewater from animal husbandry, heavy metals may keep accumulating and affecting agricultural environment. It was strongly suggested that Yunlin IA should increase the frequency of irrigation water monitoring, conduct sediment cleaning, and decrease the approval of wastewater discharge from livestock ranches to maintain reasonable irrigation water quality.

The survey of swine ranches revealed a worrisome condition in the Xiluo irrigation area. Most of the swine ranches did not handle waste properly. In general, most livestock ranches in Taiwan are in small-medium size, which let the owners or managers hardly invest in expansive waste treatment facilities and do not want to

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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 spend extra labour to deal with the waste. The new act of Taiwan Environmental Protection Administration on “livestock’s wastewater and solid waste recycling into the surround rural soils” started from January 2017 should be an effective way to reduce the amount of animal waste disposal, which might affect the irrigation water quality via RDRI. In the future, co-operation between the livestock ranches and the surrounding agricultural land should be strongly recommended in order to effectively promote the reuse of livestock waste and create additional benefit increasing the willingness of farmers to participate in recycling agriculture.

Yunlin County is the region with the largest number of swine as livestock in Taiwan (Quantity Report of Swine in Taiwan, 2019). More than 160,000 tons of waste is produced every year (The Green National Income Account, 2017). It should be worth the efforts to reuse the swine waste, both water and solid parts. Not only may the cost of livestock waste treatment be reduced but the usage of chemical fertilizers may also be decreased because of the practice of recycling agriculture.

5. ACKNOWLEDGMENTS

The authors are grateful for financial support from Taiwan Yunlin Irrigation Association (Yunlin IA), through the project of “The Preliminary Study on Enhancement Strategy of Water Quality Management in Xiluo Irrigation Area of Taiwan”. We also thank the staff of Xiluo District Management Office, Xiluo Work- station, YinxiWork-station and Dayi Work-station for their assistance during the sediment sampling and questionnaire survey in the Xiluo Irrigation Area.

6. REFERENCES

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NIEA S310.64B, NIEA M317.04B, NIEA M353.02C, Environmental Protection Administration, Executive Yuan, Taiwan. 2012.Retrieved 15 May 2019, fromhttp://www.rootlaw.com.tw/LawContent.aspx?LawID=A040300081054500-1010621 QGIS 2.18.13. 2016. QGIS Development Team, QGIShttps://www.qgis.org/en/site/ Quantity Report of Swine in Taiwan. 2018. Retrieved 15 April 2019, fromhttps://www.naif.org.tw/infoExamineList.aspx?frontTitleMenuID=37&frontMenuID=47 Registration and Management System of Livestock Ranches (n.d.). Retrieved 15 April 2019, fromhttps://aris.coa.gov.tw/farmWebSearch-ranch Sediment Standard of Assessment and Management. 2012. Retrieved 15 May 2019, from https://law.moj.gov.tw/LawClass/LawAll.aspx?pcode=O0110018 Taiwan Joint Irrigation Association. 2016. Retrieved 15 April 2019, from http://www.tjia.gov.tw/dataset-brief.asp The Green National Income Account. 2017.Retrieved 15 April 2019, from https://www.stat.gov.tw/lp.asp?ctNode=4797&CtUnit=1352&BaseDSD=7&mp=4

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