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NMSU researchers working to improve waste management

Researchers at New Mexico State University are working to improve manure management practices by combining waste from dairy farms with waste from local industries, such as paper processors, to create composting material.

The organic waste utilization project has received support from WERC: A Consortium for Environmental Education and Technology since 1996 and has made significant progress.

New Mexico has more than 170 dairies and ranks seventh in the nation for milk production and eighth for cheese production. Milk production in New Mexico generates more than 1.65 billion pounds of manure per year.

Problems related to inadequate waste management practices - such as water contamination, the spread of pathogens, increased soil salinity and noxious odors - have been addressed by the organic waste utilization project. The project, being conducted at the NMSU College of Agriculture and Home Economics Agriculture Experiment Station at Artesia, N.M., aims to alleviate problems by composting dairy manure prior to land application.

Researchers have developed a method in which water is added to the waste, which is aerated and left to sit while natural chemical digestive processes raise the internal temperature to 145 degrees. This temperature is high enough to kill pathogens or weed seeds that might be present, making the compost safe for agricultural use. The key is to maintain the temperature for 2-3 days, which provides more nutrients for plants.

The composted material retains nitrogen for a longer period of time, serving as a nutrient and allowing less of an opportunity for the nitrogen to seep into groundwater. The presence of nitrogen in groundwater would increase the salinity of the soil, causing detrimental long-term effects on agricultural production.

Composting reduces the volume of dairy manure by half, decreases salinity, reduces offensive odors, and mitigates air pollution caused by nitrogen oxides.

Problems with current composting methods lay in the consistency and manageability of the models. The most common, windrow composting, involves piles of waste about nine feet wide and three feet tall that can run several hundred feet long. The piles must be turned several times to completely aerate the waste. Temperature can be unreliable, leaving the core of the pile at the right temperature while the outside is cool enough to allow for the growth of pathogens.

Windrowing takes about a year to fully implement and the masses of waste take large amounts of space and water, and attract pests such as flies.

The next proposed step in WERC's research project is to implement an in-vessel composting structure that will allow for a controlled environment and the reuse of water, permitting the removal of saline solutions from the waste. Construction of an in-vessel composting structure is expected to begin this spring.

"The research is practical and will result in solutions for dairy waste beyond just land application," said Abbas Gassemi, WERC executive director and project director. "In addition to solving waste management problems and simultaneously addressing several environmental issues, we are looking at multiple ways, including composting methods, to enhance the inherent value of the waste."

Others involved in the effort include project co-director Robert Flynn, associate professor of extension plant sciences at NMSU; David C. Johnson, WERC program coordinator; and Cannon Consultants Inc., which is responsible for additional program and market development.

Researchers will continue to evaluate multi-year compost application on soil fertility, plant growth, water retention and soil salinity, and will track cost-benefit analyses. Also, the project will continue to assist in development of state standards for the application of compost.

The WERC consortium consists of New Mexico State University (its headquarters location), the University of New Mexico, the New Mexico Institute of Mining and Technology, Dine College and Los Alamos and Sandia National Laboratories. For more information about WERC, visit www.werc.net or call 505-646-2038.