Water use on dairy farms
How much water do commercial dairy farms really use?
Farms are major users of water. In fact, agriculture uses 70% of the fresh water worldwide. In the Great Lakes Area, water availability has not been a problem for producers. In the future, it may become more of an issue as fresh water withdrawals worldwide have tripled over the past 50 years. As rapid urbanization occurs, cities may out bid agriculture in water use. Demand for fresh water is increasing at a rate of 64 billion cubic meters per year (one cubic meter = 1,000 liters). In addition, the world population is growing by 80 million people per year, demanding more agricultural products. Farmers will need to produce double the amount of products using less water than today.
A reliable, high quality water supply is essential to dairy farms. Water is used for animal consumption, milk cooling, cleaning and sanitizing equipment, cow cooling, irrigating crops, producing value added products, moving manure and cleaning the barns via flush systems.
Using excess water has a cost including, pumping, waste water storage structures as well as transportation and application of excess water. One of the key issues in dairy herds today is the capacity to store manure and waste water until it can be land applied. The volume of wash water can occupy 25% to 50% of the total lagoon volume (Livestock Wastes Subcommittee, 1985). This wash water adds little nutritional value and can cause the manure to run-off and infiltrate into the ground water if not properly applied. Hauling costs vary greatly depending on the farm and the location of the fields but typically average $0.01 to $0.03 per gallon.
On farm water conservation can benefit everyone. Recently, a commercial dairy farm in Ohio had water use intensively followed using 13 water meters at key locations for two years. The average milk production on this farm was 80 lb/cow/day. There were 854-1005 total cows on the farm during the study period. Over the two study years, the average drinking water per cow (both milking and dry cows) was 23.6 gallons and the average waste water (water used for cleaning) was 6.3 gallons/day for an average total water use of 29.9 gallons per cow per day. This is significantly lower than the 40 to 50 gallons/cow/day commonly cited in the literature.
Metering water use on farms can be effective in managing water use and result in water conservation and reduced costs. For example, on the study farm in Ohio, the flow of water used for the plate cooler was lowered from 42 gallons per minute to 16 gallons per minute without compromising the effectiveness of the cooler. This resulted in water savings of 8 million gallons per year! In addition, a faulty valve was identified and fixed, saving 8,640 gallons per day. Other water saving practices were implemented including standardizing parlor wash down timing and fixing water trough float valves.
Based on the Ohio study, it takes approximately 4.5 gallons of water to produce one gallon of milk. In 2008-2009, Michigan produced 7,763 million pounds of milk or 902,674,418 gallons (USDA National Agricultural Statistics Service, 2009). Therefore, we can estimate that Michigan dairy farms are currently using around 4 billion gallons of water/year. Furthermore, Michigan is experiencing growth in both number of cows and the amount of milk produced per cow. Total milk production in Michigan increased nearly 33% from 2002-2009 (USDA National Agricultural Statistics Service, 2009). That could mean an estimated 1.3 billion gallon increase in water use in just the past 7 years. Will Michigan be able to supply water to sustain this continued growth?