Agriculture and Sustainable Water Use
Irrigated agriculture accounts for 70% of fresh water use worldwide, which makes it the largest user of water globally [1]. At the same time, agriculture is a major polluter of water as agricultural runoff, pesticide use, and livestock effluents all contribute to the pollution of waterways and groundwater. Most irrigated lands were introduced in the 20th century, although irrigation has been practiced for millennia. With global population expected to increase to over 10 billion by 2050, it is estimated that agricultural production will need to expand by approximately 70%. An important consequence of greater future water demand accompanied by likely reductions in supply is that the emerging competition between the environment and agriculture for raw water will be much greater, and the matching of supply and demand consequently harder to reconcile.[2] Improving water management in agriculture is crucial. And it is pressing.
Agriculture, water use efficiency and climate change
It will significantly impact agriculture by increasing water demand, limiting crop productivity and by threatening the availability of hydric resources, especially in areas where irrigation is most needed. Precipitation cycles, increased frequency and intensity of extreme phenomena, variations in soil moisture, evapotranspiration flows and surface runoff [3] are all predicted to drastically change.
About 40 percent of the world’s irrigation is supported by flows originating in the Himalaya and other large mountain systems such as the Rocky Mountains in the United States and Tien Shan in Central Asia. The loss of glaciers worldwide and snowmelt runoff will impact river systems and will change the availability of surface water for storage and diversion as well as the amount of groundwater recharge. Aquifers and semi-arid areas can expect severe reductions in replenishment, which will undoubtably impact groundwater supply.[4]
With unreliable sources of irrigation, the agricultural system is bound to encounter significant challenges while current water management is greatly inefficient. In fact, of the 70% of worldwide water use, 35-40% is lost to the environment due to evaporation, poor irrigation systems and overall poor water management.[6]
New methods of agriculture
As water use and waste is increasingly becoming a priority, farmers are starting to incorporate ways to better use our water supply. Sustainable water management aims to match water availability and water needs in quantity and quality at reasonable cost and with acceptable environmental impact. Microirrigation has gained attention in the recent years, potentially increasing yields and decreasing water, fertilizer and even labor requirements.
Through the process of drip irrigation, farmers can supply water directly to the roots of their crops instead of sprinkling the water on top and can save up to 80% more water than standard sprinkler irrigation systems. Drip irrigation is the most common type of microirrigation and one of the more advanced techniques being used today. It is a leading technology in the global challenge of boosting crop production in the face of serious water constrains.[7] In drip irrigation, “water is run through pipes with holes in them either buried or lying slightly above the ground next to the crops. Water slowly drips onto the crop roots and stems. Very little is lost to evaporation and the water can be directed only to the plants that need it, cutting back on water waste.” [8]
Many farms in drought-prone regions of the United States rely on drip irrigation as an efficient water-saving method to grow their crops. Imperial County, California’s top sweet corn producing county, illustrates the potential of drip irrigation. Studies conducted over two seasons (2020-21 and 2021-22) demonstrated that switching to the drip irrigation method allowed on average 37% less water use than farms using other methods.[9] The studies also revealed that more efficient irrigation meant less fertilizers, a win for the environment that suffers from agricultural runoff.
Studies in diverse countries as India, Israel, Spain and United States have consistently shown that drip irrigation not only reduces water use but raises crop yields by 20 to 90% and the combination of water savings and higher yields typically increases at least by 50% the water use efficiency.[10]
The different microirrigation systems
Even though the area of localized irrigation has expanded 50-fold over the last two decades, it still only represents less than 6% of the world’s total irrigated area. Unfortunately, the high investment cost, ranging from 1,500 to 2,500 € (1600 to 2600 USD) per hectare, and the high sensitivity to clogging represent significant barriers to its expansion. [12]
About the Author
Kimberley has a M.Sc in International Studies (Cooperation, Development, Economics) from the University of Montreal. She is passionate about biodiversity and Indigenous peoples' land rights. Kimberley has been working with NGOs for the past couple of years as a writer, translator and researcher. During her free time, Kimberley loves to venture on long distance hikes in the wilderness.
Linkedin: www.linkedin.com/in/kimberley-megis
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Other Nomomente articles written by Kimberly Megis:
Notes
[1] Water and agriculture. OECD. (n.d.). Retrieved June 24, 2022, from https://www.oecd.org/agriculture/topics/water-and-agriculture/
[2] Turral, H., Faurès, J.-M., & Burke, J. (2011). Climate change, water and food security. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS. Retrieved from www.fao.org/3/i2096e/i2096e00.pdf
[3] Sillmann, J.; Roeckner, E. Indices for extreme events in projections of anthropogenic climate change. Clim. Chang. 2008, 86, 83–104.
[4] Ibid at 2
[5] OECD (2014), Climate Change, Water and Agriculture: Towards Resilient Systems, OECD Studies onWater, OECD Publishing. http://dx.doi.org/10.1787/9789264209138-en
[6] J.S Wallace, Increasing agricultural water use efficiency to meet future food production, Agriculture, Ecosystems & Environment, Volume 82, Issues 1–3, 2000, Pages 105-119, ISSN 0167-8809, https://doi.org/10.1016/S0167-8809(00)00220-6.
[7] Chartzoulakis, K., & Bertaki , M. (2015). Sustainable water management in agriculture under climate change. Agriculture and Agricultural Science Procedia, (4), 88–98. https://doi.org/10.1016/j.aaspro.2015.03.011
[8] USCGS. Irrigation: Drip or microirrigation completed. Irrigation: Drip or Microirrigation | U.S. Geological Survey. Retrieved June 24, 2022, from https://www.usgs.gov/special-topics/water-science-school/science/irrigation-drip-or-microirrigation#:~:text=In%20drip%20irrigation%20(microirrigation)%2C,the%20crop%20roots%20and%20stems.
[9] Hsu, M. (2022, June). Drip-irrigation study sees 'huge' water reduction. Western Farm Press. Retrieved from https://www.farmprogress.com/water/drip-irrigation-study-sees-huge-water-reduction.
[10] Postel S., Polak P., Gonzales F. and Keller J., 2001. Drip irrigation for small farmers. A new initiative to alleviate hunger and poverty. Water Intern. 26 (1): 3-13
[11] Getting to the roots of aeroponic indoor farming - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Hydroponic-irrigation-methods-include-drip-irrigation-deep-water-culture-nutrient-film_fig1_342424160
[12] Chartzoulakis, K., & Bertaki , M. (2015). Sustainable water management in agriculture under climate change. Agriculture and Agricultural Science Procedia, (4), 88–98. https://doi.org/10.1016/j.aaspro.2015.03.011
