Agriculture—Meeting the Water Challenge


Of the vast amount of water that covers the blue earth, 2.5 percent is fresh water, and only about a third of this resource can be economically available for human use. That is a mere teaspoon in a full bathtub when compared to the total amount of water on earth. Now think about the competing demands on this finite resource—drinking, hygiene, agriculture, energy, and industry in a world of 9 billion people by 2050. It quickly becomes clear that without better water management strategies today, the world is headed for a crisis that will affect every aspect of life.

Already, 80 countries suffer from water shortages that threaten health and economies while 40 percent of the world—more than 2 billion people—does not have access to clean water or sanitation [1]. In some countries access to public water tanks is allowed only once every 45 days, often resulting in rural conflicts over water. Though the effects of water shortage are more severe in the developing world, the United States and Europe haven’t escaped unscathed.

" With the current water management practices, by 2050 the global agricultural sector will need to double the amount of water used to feed the world. "

The public usually associates water shortages with a lack of drinking water. But global water scarcity has a critical impact on food security. Water is the biggest limiting factor in the world’s ability to feed a growing population and the link between food, energy, climate, economic growth, and human security challenges.

Roughly, a liter of water is required to produce every calorie, so an adequate daily diet requires more than 2,000 liters of water to produce enough food for one person. Of this, 40 percent on global average can come from irrigated agriculture. New factors such as increasing world population and improved affluence will further strain water resources. In addition, the uncertain effects of climate change on drought, floods, and agricultural productivity will exacerbate the situation.

If we continue to apply current water management practices, by 2050 the global agricultural sector will need to double the amount of water used to feed the world [2]. With finite freshwater resources on the one hand, and increasing demand, both in quantity and variety of uses, on the other, the need for water resources protection and management has never been greater. The question is how do we meet this challenge without increasing fresh water withdrawal to feed the world?

Increasing water efficiency on the farm

Our best option is to implement solutions that have the potential of increasing the efficiency, equity and sustainability of water use. This will require a shift from the focus on pure “land productivity” without concern for water use to “water productivity,” that is, getting the highest yield out of every drop of water used in agriculture. Resource efficient methods and technology will allow farmers to grow more food with less water while protecting biodiversity.

In many parts of the world, mismanagement is depleting freshwater resources—the blue water in rivers, lakes and groundwater stores—which in turn has threatened freshwater biodiversity and permanently changed patterns of water flow. Agriculture utilizes on average 70 percent of the world’s available fresh water. But this is higher in areas such as the Middle East and northern Africa, where up to 90 percent of freshwater withdrawals are used to irrigate crops [3].

Flooded Rice paddy
Flooded rice paddies traditionally use on average about 2,500 liters of water to produce 1 kg of rough rice. As agricultural water scarcity increases, there is a growing need for water saving technologies such as aerobic rice (varieties that grow well in unflooded fields; and more efficient irrigation regimes that do not require field flooding the entire growth period. Such practices have shown water savings and increased yields.photo by Sygenta International AG,

More efficient ways to irrigate land will save tremendous amounts of water. About 40 percent of water used in irrigation is wasted through unsustainable practices such as field flooding. Modern irrigation systems can drastically reduce the amount of water used in farming by efficiently delivering water directly to plants. This reduces the amount of water lost through surface evaporation by 30 to 70 percent depending on crop and weather conditions.

Irrigation holds the most promise for increasing food productivity and security, provided it is managed efficiently. Steady irrigation combined with optimum delivery of fertilizers, seed care, crop enhancement and crop protection products can make fields more productive, even with a reliable supply of rain and is crucial to maintain productivity in times of drought.

The second part of the equation comes from the rainfall that infiltrates and remains in the soil, called green water. This is the largest fresh water resource and the basis of rain-fed agriculture. While farmers cannot control how much it rains, they can do a lot to retain rain in the soil. All rain-fed agriculture depends on the soil’s capacity to capture rain water. Heavy rain cannot penetrate parched and crusted soil and just runs off the surface.

" Farmers will not only produce more food but also become stewards of the land. "

Modest measures like conservation tillage practices that improve soil structure by avoiding plowing, mulching to prevent evaporation, and small-scale water harvesting can increase rain water infiltration by as much as 2-3 fold. However, the yields from irrigated farms are often higher than from solely rain-fed agriculture. Thus, farmers must integrate a combination of rain-fed and irrigated agricultural methods to optimize the yields of crops for the water used.

Even with optimum soil and water management, farmers will still lose crops to drought and heat if they do not have the best seeds and crop protection to carry them through inevitable dry spells.  Researchers have developed new crop varieties which are more water efficient and tolerant to heat and drought through advances in breeding and biotechnology.

In the past, breeders have slowly improved crop varieties by crossing pairs of plants that exhibit desirable qualities. Now this slow and labor-intensive method is getting a helping hand from molecular biology. Researchers are saving time by examining plant DNA for clues to predict which plant crosses are most likely to be successful in producing a given trait. Genetic modification is another tool used to improve seeds in such a way that they can produce the same or more yield with less water.

Today’s crop protection technologies can also help plants use water more efficiently. Some products have a beneficial effect on root systems, allowing plants to make the most of available water and cope better in dry periods. Plant regulator products are designed to help prevent crop loss when plants grow too tall and collapse. They also provide additional benefits by reducing water needed to grow crops. Other products are specifically designed to protect plants from moderate drought and other stresses by blocking the plant’s response to stress which increases the long-term health of plants and improves farmers’ yields.

Integrated approach to address the water challenge

There is no silver bullet—no one answer to addressing the global water challenge. But an integrated approach using the technologies outlined here and tailored to the local conditions, crops, and farmers can maximize water use efficiency.

As a result, farmers will not only produce more food but also become stewards of the land, protecting against rain run-off, soil erosion, water stress on plants, flooding, and desertification of arable land. Desertification, which occurs in arid areas from various factors, including climate variation and human activities, degrades land to the point it can no longer grow crops.

Crop Protection
A. Plants treated with crop protection product that helps sugar cane plants grow longer, stronger roots are able to access and use water more efficiently. B. Treated plot of sugar cane, on left, has deeper, stronger root system which helps the plants survive drought. Untreated plot on right is unable to withstand drought stress. photo by Sygenta International AG,

Water efficiency measures using existing agricultural technology can sustainably increase net water availability, at a reasonable cost. In comparison, trying to increase water supply often requires energy-intensive measures such as desalination, which are vastly more expensive than the efficiency measures outlined here [4].

To better manage the competing demands for water, agricultural policies will have to make water efficiency a priority. This will require investment in research to develop innovative water-efficient technologies in addition to drought tolerant seeds, new crop protection products, and optimized irrigation systems for specific crops. But the best and most innovative technology is useless if farmers cannot afford it, see no advantage to it, or do not understand it.

" Even with optimum management, farmers will still lose crops to drought if they do not have the best seeds and crop protection to carry them through dry spells."

Therefore, a key component of policymaking will have to include infrastructure for knowledge sharing and access to technology. Governments, NGOs, and public-private partnerships should facilitate implementing technology on the farm where better water management is critical for food production and the environment. This includes access to affordable credit and financial risk-management mechanisms, such as insurance for weather-related crop losses. Already the benefits of this model can be seen in partnerships between developed country governments, international organizations, and private companies which are helping small farms with access to finance, guaranteed markets, technical assistance, and insurance.

Enabling individuals and communities to understand their options for managing water, to choose from these options, and to take responsibility for their choices could positively alter the way the world uses its limited water resources.



[1] World Bank Statistics

[2] International Water Management Institute (IWMI)

[3] FAO Aquastat, 2005, World Resource and Earthscan “Water for food, water for life” Institute

[4] 2030 Water Resources Group; Charting our Water Future, Economic framework to inform decision-making; Dec 2009; http://www.2030waterresourcesgroup.com/water_full


agriculture, food security, irrigation, water efficiency, blue water, green water

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