The Limits of Water: Three Major Challenges Facing Agricultural Water Management
March 11, 2013 | Noelle Swan
“Scarcity and abundance are not nature given—they are products of water cultures. Cultures that waste water or destroy the fragile web of the water cycle create scarcity even under conditions of abundance. Those that save every drop can create abundance out of scarcity.” – Vandana Shiva, ‘Water Wars: Privatization, Pollution, and Profit‘[i]
Humans, animals, and plants all depend on water to survive. It quenches our thirst, nourishes our livestock, and sustains our crops. Civilizations have risen and fallen as a direct result of access to clean water and agricultural irrigation. Today, despite increasing technological advances in farming, we are no less dependent on water.
Every day, the U.S. agricultural industry pours 128,000 million gallons of water into irrigation, according a 2005 USGS survey of national water resources.[ii]. Aquaculture and livestock production draw another respective 8,780 and 2,140 million gallons per day, but both are dwarfed by irrigated agriculture, which represents the second largest drain on the nation’s water resources, surpassed only by thermonuclear power.
As the world’s population continues to rise, so too will global demand for food, and with it, agricultural demand for water. According to the EPA, American agriculture supplies more than a third of the global corn, wheat, and rice market.[iii] In coming decades, global food demand is expected to double.
The good news is that in our increasingly high-tech world, the technologies to better understand when and how much water plants need and to deliver it more efficiently is readily available. Soil moisture sensors can detect the actual volume of water available in the soil and are available as a simple hand held device or in automated irrigation systems. Familiar farming brands like industry giant John Deere offer a variety of drip irrigation systems designed to reduce runoff. University researchers can offer data comparing a variety of soil amendments that can improve the water holding capacity of the soil.
Despite the ready availability of such water conservation tools, much of the country’s farmland is still over-irrigated while rain-fed crops struggle to weather the whims of climate change. At the same time, economists caution that competition for water resources is expected to grow and exert added pressure on water availability for irrigated agriculture. In other words, agricultural water management is likely to get much more complicated.
Resource Competition Stresses Agricultural Water Budgets
Traditional demands on water increased drastically in the second half of the 20th century. As average home size grew, so did household water use. With urban sprawl came a bigger more concentrated public need for water. While the ERS found that those traditional demands started to level off around 2005, agricultural economist for the USDA and author of the report Glen Schiable suggested that new demands from an increasingly water-intensive energy sector are rapidly replacing and potentially surpassing that level of growth in demand.
Biofuel production uses large quantities of water to both grow and process feedstock into fuel. Hydraulic fracturing, or “fracking,” pumps millions of gallons of water mixed with sand and chemicals into underground shale formations to crack the rock and extract natural gas. Thermoelectric power plants need massive amounts of water to stay cool. These new demands place added constraints on an already taxed water supply.
“At present, irrigated agriculture across the U.S. accounts for 80 to 90 percent of total consumptive water use. If you are going to need more water to supply these growing demands, there is nowhere else to look, it will have to come out of agriculture,” Schiable says.
Schiable insists that farmers and ranchers can reduce their water use without sacrificing their bottom line by changing their water management practices. He urges farmers and ranchers to consider switching from a high pressure to low-pressure irrigation system and invest in soil moisture sensors, rather than applying indiscriminately. He adds that by applying the right amount of water when the plant needs it most, farmers will reduce the amount of water and nutrients that are wasted through runoff and leaching.
Farmers in Nebraska’s heartland have been working to incorporate this kind of data-driven water management for several decades, says Rachael Herpel, a water education and outreach specialist at the Water for Food Institute at the University of Nebraska, Lincoln. Partly thanks to their use of rain gauges and soil moisture sensors, and experience using as little water as possible, the state of Nebraska as a whole was able to bring in its eighth largest crop yield in recorded history during the summer of 2012, while the rest of the country watched their crops wither away in a bitter drought.
The Changing Climate Promises Increased Drought and Flooding
The U.S. drought of 2012 affected 60 percent of farms in America, according to estimates from the USDA.[iv] The dry conditions during a key time in the development of some plants severely damaged much of the Midwest’s corn and soybean crops for the year. The crop loss drove up the price of grain all over the world. With an increase in the cost of grain came a jump in cattle feed prices, which translated to higher meat and milk prices.
The emerging consensus among climate scientists suggests that the United States can expect more frequent and extreme weather events, including drought and floods. Increased drought places added strain on already stressed water resources, especially in regions where temperatures have started to rise. Although irrigated agriculture is designed to compensate for fluctuations in rainfall, in cases of severe drought, wells and aquifers run dry.
Too much water can be just as devastating as too little. Flooding and intense rains or hail can damage crops and cause further topsoil erosion. In 2008, intense rains caused the Mississippi River to flood right before harvest wiping out $8 billion dollars worth of crops. Wet conditions can promote growth of weeds, molds, fungus, and pests that affect plants as well as pathogens, the EPA cautions.
While scientists seem fairly certain that these kinds of events will increase in coming years, they don’t know which extreme will strike. The EPA encourages farmers to prepare for changes in precipitation and temperature by diversifying crops and exploring methods of water and soil moisture conservation. Efficient water application can help maintain a healthy layer of topsoil, increasing the water holding capacity of the soil and encouraging plants to develop deep root systems that can find their own water.
Water conservation, it seems, lies at the heart of each of these issues with the potential to free up enough water to fill the growing demand from other sectors, reduce pollution from agricultural runoff, and equip crops to better weather coming climate changes.