Irrigation

To reduce dependence on freshwater and maintain a constant source of water for irrigation throughout the year, wastewater of varying quality can be used in agriculture. However, only water that has had secondary treatment (i.e., physical and biological treatment) should be used to limit the risk of crop contamination and health risks to workers.

There are two kinds of irrigation technologies appropriate for treated wastewater:

1) Drip irrigation above or below ground, where the water is slowly dripped on or near the root area; and

2) Surface water irrigation where water is routed overland in a series of dug channels or furrows.

To minimize evaporation and contact with pathogens, spray irrigation should be avoided.

Properly treated wastewater can significantly reduce dependence on fresh water, and/or improve crop yields by supplying increased water and nutrients to plants. Raw sewage or untreated blackwater should not be used, and even well-treated water should be used with caution. Long-term use of poorly or improperly treated water may cause long-term damage to the soil structure and its ability to hold water.

Design Considerations

The application rate must be appropriate for the soil, crop and climate, or it could be damaging. To increase the nutrient value, urine can be dosed into irrigation water; this is called “fertigation” (i.e., fertilization + irrigation). The dilution ratio has to be adapted to the special needs and resistance of the crop. 

In drip irrigation systems care should be taken to ensure that there is sufficient head (i.e., pressure) and maintenance to reduce the potential for clogging (especially, with urine from which struvite will spontaneously precipitate).

Appropriateness

Generally, drip irrigation is the most appropriate irrigation method; it is especially good for arid and drought prone areas. Surface irrigation is prone to large losses from evaporation but requires little or no infrastructure and may be appropriate in some situations.

Crops such as corn, alfalfa (and other feed), fibres (e.g., cotton), trees, tobacco, fruit trees (e.g., mangoes) and foods requiring processing (e.g., sugar beets) can be grown safely with treated effluent. More care should be taken with fruits and vegetables that may be eaten raw (e.g., tomatoes) because they could come in contact with the water. Energy crops like eucalyptus, poplar, willow, or ash trees can be grown in short-rotation and harvested for biofuel production. Since the trees are not for consumption, this is a safe, efficient way of using lower-quality effluent.

Soil quality can degrade over time (e.g., due to the accumulation of salts) if poorly treated wastewater is applied.Despite safety concerns, irrigation with effluent is an effective way to recycle nutrients and water.

Health Aspects/Acceptance

Appropriate treatment (i.e., adequate pathogen reduction) should precede any irrigation scheme to limit health risks to those who come in contact with the water. Furthermore, it may still be contaminated with the different chemicals that are discharged into the system depending on the degree of treatment the effluent has undergone. When effluent is used for irrigation, households and industries connected to the system should be made aware of the products that are and are not appropriate to discharge into the system. Drip irrigation is the only type of irrigation that should be used with edible crops, and even then, care should be taken to prevent workers and harvested crops from coming in contact with the treated effluent. The WHO Guidelines for the safe use of wastewater excreta and greywater Volume II should be consulted for detailed information and specific guidance.

Operation & Maintenance

Drip irrigation systems must be periodically flushed to avoid biofilm growth and clogging from all types of solids. Pipes should be checked for leaks as they are prone to damage from rodents and humans. Drip irrigation is more costly than conventional irrigation, but offers improved yields and decreased water/operating costs.

Workers should wear appropriate protective clothing.

References

Further Readings

  • Cover image of a reference book or miscellany.

    TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; SCHERTENLEIB, R.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies (Arabic). 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). PDF

    This is the Arabic version of the Compendium of Sanitation Systems and Technologies. The Compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.

  • Cover image of a reference book or miscellany.

    DRECHSEL, P. (Editor); SCOTT, C.A. (Editor); RASCHID-SALLY, L. (Editor); REDWOOD, M. (Editor); BAHRI, A. (Editor) (2010): Wastewater Irrigation and Health. Assessing and Mitigating Risk in Low-Income Countries. London: Earthscan. URL [Accessed: 15.05.2012]. PDF

    This book is written for practitioners, researchers and graduate students in environmental and public health, sanitary and agricultural engineering, and wastewater irrigation management in developing countries. In particular, it should be useful for all those working to assess and mitigate health risks from the use of wastewater and faecal sludge in agriculture, under conditions where wastewater treatment is absent or inadequate to safeguard public health. In this respect, the book builds on and complements the international Guidelines for the Safe Use of Wastewater, Excreta and Greywater published in 2006 by the World Health Organization in collaboration with the Food and Agriculture Organization of the United Nations and the United Nations Environment Programme.

  • Cover image of a reference book or miscellany.

    FAO (Editor) (2012): On-Farm Practices for the Safe Use of Wastewater in Urban and Peri-Urban Horticulture. A Training Handbook for Farmer Field Schools. Rome: Food and Agriculture Organization (FAO). URL [Accessed: 15.04.2014]. PDF

    This training handbook is a field guide for training urban and peri-urban vegetable farmers in safe practices when using wastewater in vegetable production. It is designed to provide complete information, knowledge and skills for safer and successful production of vegetables in urban and peri-urban farming systems.

  • Cover image of a reference book or miscellany.

    JOENSSON, H.; RICHERT, A.; VINNERAAS, B.; SALOMON, E. (2004): Guidelines on the Use of Urine and Faeces in Crop Production. Stockholm: EcoSanRes. URL [Accessed: 17.04.2012]. PDF

    These guidelines provide a thorough background on the use of urine (and faeces) for agricultural purposes. Aspects discussed are requirements for plant growth, nutrients in excreta, hygiene aspects, and recommendations for cultivation. It provides detailed guidance on the use of urine for purposes.

  • Cover image of a reference book or miscellany.

    NPSI (Editor) (2005): Subsurface irrigation. Factsheet. Canberra: NPSI. URL [Accessed: 12.07.2010]. PDF

  • Cover image of a reference book or miscellany.

    PALADA, M.; BHATTARAI, S.; WU, D.; ROBERTS, M.; BHATTARAI, M.; KIMSAN, R.; MIDMORE, D. (2011): More Crop Per Drop. Using Simple Drip Irrigation Systems for Small-scale Vegetable Production. Shanhua, Tainan: AVRDC - The World Vegetable Center. URL [Accessed: 18.01.2012]. PDF

    Simple low-cost drip irrigation is practical and affordable for smallholder farmers. It has been successfully used in India and is becoming more popular in other southeast Asia and sub-Saharan Africa. It can reduce both water and labor use by as much as 20-50%. Yield of vegetables also can be increased by at least 10%. Our farm trials in Cambodia showed yield increases of 20-50% compared to traditional hand watering. Low pressure irrigation is also a key component of the African Market Garden concept jointly developed in west Africa with ICRISAT. This 10-chapter drip irrigation manual provides basic, step-by-step procedures for installing simple drip irrigation systems for different crops, climates, and soils.

  • Cover image of a reference book or miscellany.

    PESCOD, M.B. (1992): Wastewater Treatment and Use in Agriculture. Rome: Food and Agriculture Organisation of the United Nations (FAO). URL [Accessed: 25.10.2011].

    This Irrigation and Drainage Paper is intended to provide guidance to national planners and decision-makers, agricultural and municipal managers, field engineers and scientists, health and agricultural field workers, wastewater treatment plant operators and farmers. Consequently, it covers a broad range of relevant material, some in considerable depth but some more superficially. It is meant to encourage the collection, treatment and use of wastewater in agriculture in a safe manner, with maximum advantage taken of this resource. Informal, unplanned and unorganized wastewater use is not recommended, nor is it considered adviseable from the health or agricultural points of view.

  • Cover image of a reference book or miscellany.

    SHOCK, C. (2006): Drip Irrigation: An Introduction. Corvallis: Oregon State University. URL [Accessed: 23.06.2011]. PDF

    A document about drip irrigation system including components, design advices, management of the system and additional resources.

  • Cover image of a reference book or miscellany.

    WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010]. PDF

    Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.

  • Cover image of a reference book or miscellany.

    WINPENNY, J.; HEINZ, I.; KOO-OSHIMA, S.; SALGOT, M.; COLLADO, J.; HERNANDEZ, F.; TORRICELLI, R. (2010): The Wealth of Waste. The Economics of Wastewater Use in Agriculture. Rome: Food and Agriculture Organization (FAO). URL [Accessed: 15.04.2014].

    This report presents an economic framework for the assessment of the use of reclaimed water in agriculture, as part of a comprehensive planning process in water resource allocation strategies to provide for a more economically efficient and sustainable water utilization.

Case Studies

  • Cover image of a reference book or miscellany.

    ANDERSSON, L. (2005): Low-Cost Drip Irrigation. On Farm Implantation in South Africa. Lulea: Lulea University of Technology . URL [Accessed: 23.06.2011]. PDF

    Small-scale rural farmers’ perceptions, attitudes and preferences of low-cost drip irrigation systems were investigated through a series of interviews conducted before, during and following their use of such systems. Responses were analysed to determine the technological, socioeconomic and cultural suitability of the systems.

  • Cover image of a reference book or miscellany.

    GERMER, J.; KANGNING, X. (2009): Urine diversion sanitation in Olympic Forest Park. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 07.07.2010]. PDF

    Urine diversion low-flush toilets where installed in public toilet blocks of the Olympic park. Urine was collected for reuse and brownwater was treated in a septic tank and moving bed reactor before being transformed into compost. The aim of the system was to interlink the sanitation material flows as a water and nutrient source with the green areas of the park as a water and nutrient sink. Reduced water and energy demand as well as the substitution of fertilizer by urine and faeces-derived manure were expected advantages.

  • Cover image of a reference book or miscellany.

    HOLMER; ROBERT J. (2003): Water Management Strategies for Year Round Vegetable Production in Cagayan de Oro City. URL [Accessed: 13.08.2010]. PDF

    This paper contains information about strategies on how to manage water for a year-round production using fertigation as one of the options.

  • Cover image of a reference book or miscellany.

    MUELLEGGER, E. (Editor); LANGERGRABER, G. (Editor) (2012): Water Reuse. Vienna: EcoSan Club. URL [Accessed: 18.07.2012]. PDF

    To meet the challenges extremely efficient water use is necessary to achieve overall improvements in water productivity. Multi-use systems will therefore be crucial in integrated water management. Different examples show how water can be reused and recycled and thus increasing water efficiency in urban, peri-urban and rural areas. Issue 11 of Sustainable Sanitation Practice (SSP) on „Water reuse“ shows 3 examples for the use of treated wastewater for irrigation in agriculture: (1.) The first paper presents results from a long-term study (agricultural wastewater reuse) carried out in Sicily, Italy. (2.) The second paper presents activities on water management in the Oasis of Figuig, Morocco. (3.) The third paper presents practical experiences from a feasibility study on technology selection for wastewater treatment and effluent reuse schemes in Anza village, Palestine.

  • Cover image of a reference book or miscellany.

    PALRECHA, A.; KAPOOR, D.; MALLADI, T. (2012): Wastewater irrigation in Gujarat: An exploratory study. Gujarat, India: IWMI-Tata Water Policy Program. URL [Accessed: 15.01.2013]. PDF

    Sewage farming, as it is called by farmers, is the use of untreated or partially treated wastewater for irrigation. This paper explores the prevalance of wastewater use and also the benefits and threats posed by this practice. Wastewater reuse conserves fresh water and nutrients, is inexpensive, and reduces pollution of water systems. The paper brings out several recommendations by farmers to increase the benefits of this system, one of which is planning STPs to maximise the amount of land that can be cultivated.

Awareness Material

  • Cover image of a reference book or miscellany.

    EAWAG (Editor); Khoang Development Forum (KDF) (Editor) (2011): How to Use Urine in Drip Irritation. Duebendorf: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 15.04.2014]. PDF

    This factsheet gives information on the use of urine in drip irrigation.

Training Material

Important Weblinks

  • www.eawag.ch [Accessed: 15.12.2011]

    Webpage on drip irrigation (with urine) from Swiss Federal Institute of Aquatic Science and Technology or Eawag which is doing research on this topic mainly in Nepal.

  • http://www.fao.org/ [Accessed: 23.06.2011]

    This website is an attempt to distil current information on irrigation methods that might be appropriate, and to offer some ideas on the possible adoption and adaptation of such methods by small-scale farmers in the semi-arid areas of sub-Saharan Africa.

  • http://www.infonet-biovision.org

    Water for irrigation: different irrigation techniques and tips for using water for irrigation