Farmers in Yuma County strive to protect aquifer’s water quality

by Laurie DiBattista

Farmers in Yuma Conservation District’s Water and Nutrient Management (319) Project recently learned that results of deep soil test on their crop fields showed they are doing a good job agronomically to protect the quality of the Ogallala Aquifer – the key water source for the area.

As part of the grant project, Michael Petersen, a National Resources Conservation Service soil scientist, took soil samples from an assessment area. Thirty fields were selected from 10,000 acres enrolled in the program to determine if nitrogen from fertilizer applications is escaping below the root zone.

Samples were taken at six feet, which show management practices in the last several years, and nine feet, which show management practices 10 to 15 years ago. Samples were collected from three sites in each field.

The assessment area fields were selected to represent major soil types, topography, and cultural practices in the project area, and sample sites in each field were selected to be representative of the whole field. Results were sorted by sandy, loamy and clay soil types.

The data indicates past and present nutrient management practices, and whether all the nitrogen is used by the crops or has escaped below the root zone. At the six-foot depth, the average of all the samples was 5.7 parts per million of nitrogen, or about 20 pounds an acre. While at the nine-foot depth, the average was 4.8 parts per million, or about 17 pounds per acre.

Those results prompted Petersen to conclude that "the crops are using almost all of the nitrogen applied."

The project promotes voluntary adoption of management practices aimed at reducing nonpoint source pollution, increasing irrigation efficiency, and protecting the quantity and quality of water in the Ogallala Aquifer.

"It’s a complicated aquifer because it’s so large and there is a large variety of (farming) practices," said Lynda Harper, district manager of the Yuma Conservation District. "There is a high contamination in some areas of other states. We were concerned about the lack of data here so we’re being proactive in trying to prevent any problems."

The Ogallala Aquifer, a nonrenewable resource, is the sole source of water for all uses – industrial, municipal and domestic – in this part of Colorado, making it the district’s most important natural resource issue.

The aquifer is one of the largest in the world, extending across parts of South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico and Texas. It underlies about 156,000 square miles. The Colorado portion of the Ogallala is about 8 percent of the total area of the aquifer, underlying approximately 12,000 square miles.

Farmers and others in western Yuma County have continued to identify water quality and quantity as top priorities, particularly protection of groundwater in the Ogallala Aquifer.

"We have had good buy-in from landowners," according to Harper, for the 3 1/2-year, $237,500 project that began two years ago and includes 10,000 acres of irrigated cropland, mostly corn. Yuma County, bordering Kansas and situated in the High Plains, is Colorado’s leading corn producer, growing about 25 percent of the state’s crop.

Project activities are designed to support and encourage agricultural practices that reduce runoff over the Ogallala Aquifer. The project’s best management practices (BMPs) have three required components: irrigation water management, nutrient management and pest management. Farmers enrolled in the project receive cost share payments of $2.50 an acre toward hiring a certified crop advisor to make BMP recommendations.

Consideration is being given to extending the project into the next phase by increasing acres in the study, taking deeper samples, adding leaf tissue studies and including information about tillage practices. There may also be deep soil testing of native grasslands in the area in order to compare findings with samples taken from cropland.

For more information about the project, contact Lynda Harper at 970-848-5605, or visit www.plains.net/~ycd.