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New Mexico State University

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NMSU Develops Nutrient Management Software for Dairy Manure

ARTESIA - Newly developed software could help turn manure into an asset instead of a liability, say New Mexico State University scientists. They've designed a spreadsheet-based program to more effectively use the millions of tons of manure produced across the state.



Robert Flynn, an agronomist with NMSU's Agricultural Science Center at Artesia, checks compost conditions at a Roswell dairy. NMSU and the USDA's Natural Resources Conservation Service developed a new computer software program to more efficiently use nutrients in compost, manure and effluent water for specific crop and field locations. (05/16/2002) (NMSU Agricultural Communications Photo by Norman Martin)

Over the past 20 years, the state's supply of manure has grown exponentially. In 1981, there were about 49,000 dairy cows in the state, compared with 261,000 last year. The dairy growth is concentrated in six counties: Chaves, Dona Ana, Roosevelt, Lea, Curry and Eddy.

Combine all those cows with alfalfa, corn silage and water and you get 5.2 billion pounds of marketable milk, along with 3.3 million tons of manure per year. That waste has to go somewhere, and NMSU scientists set out five years ago with a U.S. Department of Agriculture grant through WERC, a consortium for environmental education and technology development, and NMSU's College of Agriculture and Home Economics to find beneficial ways to use manure as a fertilizer for crops.

The result is a new computer workbook that steps away from a one-size-fits-all approach to field applications by effectively using the nutrients in manures and effluent waters for specific crops and field conditions. "We've merged together several sciences, including irrigation water management, microbiology, chemistry and economics," said Robert Flynn, an agronomist with NMSU's Agricultural Science Center at Artesia.

One of the program's goals is to promote broader use of compost from dairy manure. Composting can actually become a management tool for dairies because it reduces manure volume, Flynn said. The process stabilizes the material, reduces weed seed viability and makes it much more uniform, which allows for more uniform application than raw, dry manure.

Demand for organic fertilizer is growing, much of it moving along what's known as the alfalfa road, the route for hauling Colorado-grown alfalfa to New Mexico dairies, and returning with compost. While manure is low in nutrition compared to synthetics, there are other advantages to using the compost, including improved water-holding capacity and soil structure.

"Composting is economical as long as the cost of hauling and application does not exceed the cost of synthetic fertilizer application," Flynn said. "One of the things we'd like to document is any long-term economic benefits to using manure."

Using Microsoft Excel as a software platform, Flynn and Michael Sporcic, an agronomist with the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS), produced a series of electronic worksheets in which soil test data, the specific crop and yield goals are entered, along with the manure or effluent nutrient values. The program provides an estimate of the available nitrogen and the application rate that will meet that specific crop's needs.

Application rates can be adjusted based on salt content or other factors that may have a detrimental effect on crop production. Without a measured application of manure, the salinity of manure can injure or burn crops. "Our goal was to supply enough nutrients for plant production, but avoid excessive applications in order to prevent leaching of nitrates or the build up of excessive salts," Flynn said.

The software was designed specifically for New Mexico's agricultural conditions, using NMSU test plots at its science centers in Artesia, Clovis and Los Lunas for agronomically viable baseline data. To verify the software, Flynn conducted a broad series of replicated application studies using compost, fresh manure and effluent water. Other of his studies have offered side-by-side comparisons of compost, manure and synthetic fertilizers looking at soil quality and nutrition factors in alfalfa, corn, cotton and chile.

Albuquerque-based Sporcic, who did much of the actual spreadsheet programming, said beta versions of the software are available now from the Extension service and NRCS. "We're at a point now of expanding use of the software to county Extension agents in New Mexico and more than 70 NRCS personnel, as well as individual producers," he said.

In addition to providing application rate recommendations, the software has record keeping capabilities, Sporcic said. Federal guidelines require that dairies maintain records of where and how much waste material is applied. The state agencies also are examining a national record keeping initiative for environmentally sound waste management.