Focus on the Environment: Agriculture is playing its part in water conservation

Tuesday, March 2, 2010

Agriculture has reduced water use considerably through improved health, housing, breeding, feeding and management and our farmers will continue to provide leadership in water use

by JIM DALRYMPLE

With Canadian, North American and world populations expected to increase significantly over the next 20 to 30 years, the demand for fresh water will rise dramatically. This will escalate the need for water for food, fibre and fuel.

Many areas of the world have already experienced declining water tables, increased costs for water withdrawal and, in some cases, deterioration in water quality. Rising living standards throughout the world will add to demand for water, while climate change and droughts in several parts of the world will affect the abilities of many countries to maintain or increase their food production capabilities.

Agriculture accounts for three per cent of Canada's gross domestic product, making it one of the largest sectors in the country. Approximately seven per cent of Canada's land is used for agriculture – about 67.5 million hectares.

Water in Canada is used for many competing purposes, including municipal use, agriculture, thermal power generation, manufacturing and mining. Current rising (see Figure 1) water use in some Canadian towns and cities is problematic for both environmental and economic reasons. These include water shortages; surface water draw-down affecting aquatic and terrestrial habitation and other water uses; groundwater draw-down; strain on water and wastewater infrastructure and services; and wastewater dilution, reducing the efficiency of wastewater treatment processes.

Although agriculture is not Canada's largest user of water, it is the largest consumer, according to Environment Canada's report, "Land and Water Use." Nationally, 44.61 billion cubic metres of surface water are withdrawn from Canadian rivers by major users (1996). However, agriculture withdrew only nine per cent compared to thermal power (64 per cent) and manufacturing (14 per cent).

Even though recorded statistics show only about 10 per cent (4.5 billion cubicmetres) of water withdrawn is actually consumed, agriculture consumes 71 per cent of the water it diverts, making it by far the greatest consumer. About 85 per cent of agricultural withdrawals (surface and ground water) are used for irrigation (primarily in Western Canada) and 15 per cent is used for watering livestock.

Irrigation. Due to Canada's climatic conditions, systems for both good drainage and irrigation are often essential for successful agricultural production, particularly in Western Canada.

The majority of irrigation in Canada is through sprinkler and drip systems, which lessen the environmental impact on the soil and water compared with flood irrigation.

Agriculture has been adopting technologies and management practices that will optimize the amount of water diverted per unit of crop yield through improved efficiencies in storage, distribution and on-farm utilization. Scheduling irrigation to meet crop water demands, increased yields per acre, suppression in evaporation losses and production of higher value crops all help to reduce the impact of agriculture on water use.

For annually seeded crops, conservation tillage practices, developed and widely accepted over the past 30 years, have greatly reduced surface losses of water, sediment and nutrients to waterways. A 60 per cent reduction in surface runoff was reported in Quebec no-till corn compared to conventional tillage.

Livestock. Livestock production is an important component of Canada's agri-food industry. To produce milk, meat and eggs efficiently requires a stable supply of high quality water (see Figure 2).

In some areas in Canada, such as parts of Quebec, expansion of intensive livestock production has been reduced as a result of water quality concerns.

Large-scale livestock operations have been adopting water management practices to reduce wastewater. These practices include nipple drinkers in swine facilities, high-pressure washing equipment for pens, and improved milk house cleanup in dairy operations.

Agriculture has reduced water use considerably through improved health, housing, breeding, feeding and management. A market hog now requires 40 per cent less water to reach its market weight than a few decades ago. Dairy cattle numbers are down dramatically from 50 years ago and production per cow has tripled. Census of Agriculture data showed annual production in 1950 at 2,413 litres per cow per year with current production approximately 7,000 litres per cow per year. The number of dairy cows on Ontario farms decreased from over 900,000 to 350,000 over the same period.

Households now use more water, with the average daily use per person at over 350 litres. This is twice as much water as the average European uses in a day.

Future trends and emerging issues. A greater supply of Ontario's food supply is imported than ever before. California has experienced long droughts and a diminishing water supply, which could reduce our ability to import U.S. fruits and vegetables.

The Council of Agriculture Science and Technology (CAST) in the United States expresses concern about California's surface and ground water availability and quality.

Already large dairy units are having difficulty meeting their water requirements. The dairy operations in the Central Valley of California house 1.5 million milking cows and produce more than 15 per cent of U.S. milk and cheese.

CAST reports that Florida's 18 million people are largely urban (94 per cent), but agriculture – mostly through irrigation – accounts for 53 per cent of freshwater use. 

Farmers have been increasing their diligence related to water use and will continue to do so. But the demands of rural subdivisions, golf courses and water recreational use will put increased pressure on water use in agriculture.

Wireless and computer technologies will increase precision application of water and accurate local weather forecasting will assist farmers in timely application of irrigation needs.

Through new technologies and improved productivity, farmers will continue to provide leadership in water use. BF

J.R. (Jim) Dalrymple, P.Ag., CAC, is a former Ontario government swine specialist and owner of Livestock Technology Services in Brighton.