Irrigated mountain hayfields can act as large filtration systems that reduce sediment, phosphorus and other contaminants from runoff, sometimes improving the quality of water flowing back into the environment, Colorado State University research has found.
The findings result from a producer-driven, three-year study by CSU's Agricultural Water Quality Program in the Yampa, Gunnison and Colorado River basins.
The examination of agricultural impacts on water quality found consistently low nutrient concentrations in runoff from Colorado hayfields – lower than levels warranting concern and sometimes lower than when the water was applied to fields.
"These irrigated ag lands in the mountains are essentially large grass filter strips," said Erik Wardle, director of the Agricultural Water Quality Program, who conducted the research. "Their impacts are very low, and in some cases, they even have the potential to clean the water, depending on management and localized conditions."
Excess nutrients, such as nitrogen and phosphorus, can cause algal blooms, which are unhealthy for people and animals, especially aquatic life. These nutrients are found in fertilizer, but they're also found in nature, wastewater and urban stormwater.
Planting perennial grass strips along the edges of fields where row crops such as corn and soybeans are grown is a best practice to prevent fertilizer and sediment from running off into water supplies. The study found that Colorado's mountain meadows, which are large perennial grass fields, serve this purpose when nutrients required for plant growth are managed judiciously.
Data from the study benefits producers and state agencies by providing baseline measurements and showing that voluntary adoption of best management practices can effectively mitigate the impacts of agricultural nutrient use in mountain meadow hay systems.
Colorado's nutrient control Regulation 85 restricts nutrients to protect water quality. The Water Quality Control Division monitors wastewater treatment plants and some industrial sources but currently does not regulate most agricultural systems. However, agriculture is continually evaluated, and the division has the authority to recommend regulations if deemed necessary. For now, agricultural producers are tasked with using best management practices and demonstrating sufficient progress in water quality protection.
The Colorado Ag Water Alliance, a group of producers and partner organizations dedicated to preserving water resources, requested the study to understand whether hay production and grazing were contributing nutrients to mountain surface water. The study was funded by the Colorado Department of Public Health and Environment and the Environmental Protection Agency. Several producers, one in each basin, volunteered their property for water quality monitoring. CSU's Agricultural Water Quality Program tested irrigation water before and after it was applied to fields.
Greg Peterson, executive director of Colorado Ag Water Alliance, said this was the first study of its kind to examine mountain meadow hay operations and water quality.
"A lot of us in the agricultural community were a bit worried about experimenting with these kinds of practices, because what if we see something wrong? Are we going to get in trouble?" Peterson said. "But it really gave participating producers the freedom to experiment and identify things that were a benefit to them and water quality."
Mountain meadow hay has a short growing season, and producers in these systems typically don't use much fertilizer, which is expensive. Participating in the project allowed them to test different management practices to optimize fertilizer use and water quality.
"One of the sites was just open space, and there wasn't much difference from the local ranch and that open space site," Peterson added.
Colorado Farm Bureau President Carlyle Currier, who is also a board member of the Colorado Ag Water Alliance, said he was pleased with the results of the study. Currier chose to evaluate the area of his ranch he was concerned had the most potential for contamination. Results validated that the water leaving his field was generally better quality than the water used to irrigate it.
"Farmers and ranchers are the original environmentalists," Currier said. "We use natural resources to produce our crops and livestock, and they're very dependent on having a good clean environment. We'd destroy our livelihood if we destroy the environment. My family's been in operation on the same land for well over 100 years. To know that we are protecting the environment and doing things right is very good for us."
Hay production and forage pastures feed livestock, Colorado's top agricultural commodity. Wardle said ranches are important to mountain communities and the economy.
"Many of these ranches have been there 100 years or more, so they're very much a part of the ecosystem in the mountains," he said.
The mountain meadow hay study has led to a new Colorado Water Plan project in the Yampa River Basin. The new project will demonstrate and evaluate best management practices in mountain meadow hay systems, building on this producer-driven research.
The report, "Nutrient Management on Irrigated Pastures," is available upon request.
