Water Use Transformation Required by Agriculture,

Published by: Mark Lowey
in Climate Change, Issue 2 & 3
 
Water Use Transformation
Required by Agriculture,
UBC Expert Says
By Elona Malterre
            LETHBRIDGE – The agriculture business must transform how it uses water in light of increasing demands for the diminishing resource and the climate change impacts, says an internationally recognized water expert.
            “Globally, agriculture uses approximately 70 per cent of all freshwater resources. Urban use is relatively small but is growing rapidly,” Hans Schreier, a professor with the Institute for Resources and Environment at the University of British Columbia, told the Water, Agriculture and the Environment conference in Lethbridge.
            For example, it takes between 15,000 to 70,000 kilograms of water, depending on various factors, to produce just one kilogram of beef, Schreier noted. Irrigation agriculture produces half the world’s food supply, with some countries relying on irrigation for 80 to 90 per cent of crop production, he said. “Most groundwater resources are being challenged.”
            “The big challenge . . . (is that) agriculture wants more water for irrigation, mining extraction wants more water, urbanization wants more water and for the first time we really have to allocate water for environmental services,” Schreier said.
            Coupled with global demand for more water is the impact of climate change. Climate change models don’t adequately consider changes in land use, and the effects of climate change along with land-use changes probably have a “synergistic effect” on water availability and quality, he said.
            Climate change is also changing the “hydrograph” of every river, Schreier noted. Predicting the amount of precipitation, especially in mountain regions, is unreliable because these regions “are warming up faster” compared with other geographical areas. The largest temperature increases are occurring in high mountain ranges, where declining snowpacks have “huge implications” for water resources, he said.
            The agriculture-intensive area around Abbotsford, B.C., for example, had huge swings in rainfall and drought conditions over one year. In January 2006, the area received 100 per cent higher than average rainfall, but in July and August of the same year had only one-third of the average rainfall. 
            Along with uncertainty about future precipitation/runoff and land-use changes, “for the first time now we have to start thinking about the variabilities of the economic system. So these three factors are going to interact dramatically,” Schreier told the more than 200 conference delegates.
            In a presentation entitled “Agriculture’s Water Footprint and Environmental Health,” he said that society’s models for calculating water usage are outdated, because in fact there are three ‘kinds’ of water. “Blue water,” which includes rainfall, rivers, lakes and groundwater, is “what we manage. Almost everything we do is blue water.”
            “Green water” is utilized by plants, creates biomass and “evapo-transpires.” “There’s twice as much water cycling in that (green water) cycle as in the blue cycle and we don’t pay much attention to it except maybe in irrigation . . . That’s where we have a lot of capacity to improve,” Schreier said.
            Finally, there is “virtual water,” which is the huge amount of water used in transitional food stages in producing a product – turning grapes into wine, for example. Society has mostly ignored this virtual water use, but “we have to start paying attention to that.”
            In a slide he called his “horrendogram,” Schreier illustrated the impact on water resources due to agricultural intensification and agricultural expansion into marginal lands. Problems include salinity, leaching, decline of organic matter in soil, nutrient imbalances and erosion.
            Since so much freshwater is used for irrigation, “if we invest wisely, we can improve our efficiency immensely,” he said. “Water use efficiency starts with green water management.” For example, underground cisterns are used in parts of Africa that receive very little annual rainfall to capture runoff.
            In B.C.’s Okanagan, Canada’s driest watershed, the population increased to 317,000 in 2001 compared with 115,000 in 1971 – a jump of about 175 per cent. The number of golf courses rose 600 per cent. Wineries increased 580 percent. “Everything we do in this watershed is water intensive,” Schreier said.
            The Okanagan is one of the few areas in Canada where grapes and fruit can be grown, but most of the irrigated water is being used to grow grass, “followed by apples and alfalfa . . . this is not growing water in a green context,” he said. “Why not start looking at green water management and look at what is the best crop in the climactic conditions to give the best added value?”
            Greenhouses currently have the highest water use per hectare in the Okanagan, followed by “turf” and golf courses, Schreier said. Based on water use figures, one Osoyoos area golf course is 21 per cent over-irrigated, while another Kelowna area course is 40 per cent over-irrigated, he noted.
            When it comes to staple crops, such as potato, wheat, alfalfa, sorghum, corn, rice and soybeans, they all take about 1,000 litres of water per kilogram, except rice which requires about 2,000 litres, Schreier said.
            When it comes to meat production, chicken requires about 5,000 litres of water per kilogram, while beef takes between 15,000 and 70,000 litres. “Massive amounts of water are needed to produce meat.”
            North Americans, who eat large amounts of meat, use about 5,000 litres of water per person per day just to maintain their diet. Latin Americans use approximately 2,800 l of water per day, while Southeast Asians require only 2,110 l.
            As populations become better off economically, they consume more meat protein, “and when you do that, we’re going to need a lot more water,” Schreier pointed out. “This is very important for Alberta, because there aren’t that many countries that can actually increase meat production.”
            China, for example, now has 300 million people whose economic wealth is equivalent to that of the North American middle class. Although China has 40 per cent of the world’s pigs, since 1999 the country has been “importing massive amounts of beef, veal and chicken.” As the Chinese economy grows stronger, the country will continue to import larger amounts of chicken and beef, Schreier said. “And that beef isn’t going to come from China. It’s going to come from elsewhere.”
            Schreier referred to the “water footprint” as the total volume of freshwater required to produce the foods and services consumed by the individual, business or nation. This footprint is usually described as the volume of water used per year: for example, it takes 1,350 litres of water to produce one kilogram of wheat.
            “If we’re going to pay attention to rain-fed agriculture, we really need to pay attention to the kinds of crops that will grow here in Canada,” he said.
Cereal crops require less water compared with meat, milk and coffee. “A glass of milk takes about 200 litres of water to produce . . . a cup of coffee takes about 148 litres of water.”
            When it comes to growing crops for biofuels, Schreier called the practice in North America “an absolute disaster.” Fifteen percent of corn production and 18 percent of agricultural land in the U.S. is currently used for ethanol production, he noted. “In terms of the amount of ethanol you produce from corn, it’s actually very low compared to sugar cane or sugar beets or oil palm.” (See Vol 17 #17&18 pg 7) Sugar beets yield 400 litres of ethanol per hectare, corn 200 litres and wheat 150 l.
            Wheat also requires about 4,800 l of water to produce one litre of ethanol, while canola needs 1,700 l of water to yield one litre of biodiesel. Sugar beets need only 100 l of water to produce one litre of ethanol. 
            Given those water use figures, it makes much more economic and environmental sense for tropical countries to produce the world’s ethanol from cane and beet sugar, while North America grows its cereal crops for food, Schreier said.
            In addition to growing global demands for water, concerns are mounting about water quality. There are now six billion people in the world, and the amount of nitrogen released in human waste is approximately four kilograms per person annually, he said.
            If the amount of nitrogen in the waste produced by all the world’s sheep, goats, pigs, chickens and other livestock is ‘converted’ to the equivalent of cattle waste, it totals three billion bovines. Cattle waste contains seven times the amount of nitrogen compared with human waste, so this amounts to “the equivalent of 21 billion people,” Schreier maintained.
            The amount of excess nitrogen and phosphorus in B.C.’s Fraser Valley is increasing, with “massive phosphorous surpluses” of more than 150 kilograms per hectare per year, he said. While tests in forested areas show fewer than 10 ‘measures’ of E.coli bacteria, there are hundreds of E.coli counts in agricultural areas and thousands in intensive agricultural areas.
            Societies treat human waste, Schreier said, adding: “I think the time has come when we have to start thinking about treating this (livestock waste),” including by recovering phosphorus and building biogas facilities. Water conservation and “water harvesting” strategies are needed.
            The current “minimum-flows” approach to protecting waterways is a big scientific challenge and a top area for research, Schreier said. A more flexible and innovative approach would be to “(mimic) a natural river system, which means magnitude of flow, timing of flow, frequency of flow variations . . . We need to fluctuate the system in order to maintain the biodiversity.” EnviroLine

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