Through remarkable technologies such as anaerobic digestion, agriculture is working to develop waste management options that are sustainable and ecologically sound. Even those dairy producers who operate on smaller scales should be aware that adopting cleaner practices starts with dirtying the hands.

Holly Drankhan

There are a number of methods for manure handling used in the dairy industry, with minute changes in collection, transport, storage and application compounding this variation.

The major challenge is to choose a system that upholds the best stewardship standards while still maintaining profit margins and minimal labor. While no system is perfect, producers continually refine their practices as they expand to find one that best serves their facility’s needs.

One such individual is John Ruedinger, president of Ruedinger Farms Inc. in Van Dyne, Wisconsin. In 18 years, his operation has expanded drastically from a milking herd of 200 to 1,200.

Converting from mattress-lined stalls and a central holding pit to sand bedding and a manure auger system has helped better accommodate the approximately 13 million gallons of manure produced annually. A three-stage lagoon scheme incrementally increases solid separation.

The soft footing of sand ensures greater comfort for the animals, leading to higher milk yields, and the concrete lining of the clay pits simplifies cleaning. However, opting out of establishing a sand-separating system to invest more in other areas of facility development, Ruedinger estimates an annual expenditure of $90,000 on removal and more than $100,000 on purchasing new sand.

By contrast, nearby Lake Breeze Dairy utilizes a flush system and sand-settling lanes to recycle bedding from their double-44 parallel parlor. After drying for three to four months, this sand is ready for re-use.

Operations Manager Mark Diederichs says that while cost-effective in the long run, and labor-saving, the system has one major problem of odor from flush water. The farm was able to cease the use of farachloride for odor prevention by drilling new wells to improve water quality.

Lake Breeze Dairy is also in the midst of a two-year trial of a partial calcium and ammonium salt manure additive, which aims not only to reduce odor but also improve nutrient retention, and thus crop yield, by decreasing nitrogen volatilization and phosphate lock-up. Though already experiencing some positive results, Diederichs explains there are a number of factors to consider before implementing new products.

“We purchase all of our feed, so we don’t grow any crops ourselves. So for it to be beneficial for us in the continued years, we have to offset some of our costs with our growers,” Diederichs says.

Ruedinger also obtained positive results from the product, claiming that it showed visible signs of fiber degradation in the pit and made aggregation easier. The dairy producer supports that willingness to implement emerging tools is key in finding a handling method that is both efficient and sustainable.

“Always look at better ways to haul and incorporate manure, and don’t be afraid to try new products to aid in the breakdown of manure,” encourages Ruedinger. “While those will cost you money, someday you will find a product that will be beneficial to your operation.”

Federal, state and local regulations are another important factor in ensuring proper waste management. In Wisconsin, the DNR requires concentrated animal feeding operations (CAFOs) to have a five-year Wisconsin Pollutant Discharge Elimination System (WPDES) permit.

This requires regular monitoring of wells, lines and pits for leaks, the development of a response plan for spills, the accommodation of at least six months’ worth of liquid waste for all holding chambers and no application of manure to frozen or snow-covered land.

Any engineering changes to manure systems must be reviewed and approved. In addition, yearly nutrient management plans (NMPs) assess soil quality and determine the best timing and methods for manure application.

“There are some hoops you have to jump through to make sure that you remain in compliance with it, but it does make you aware of what is going on within your dairy business when you follow that plan and look at it,” Ruedinger says of NMPs.

“A lot of people just take the plan and put it on the shelf and not really look at it a lot. We look at ours from time to time just to make sure, more so when we are applying nutrients, that we are monitoring our different field and soil types.”

Proper timing, quantities and methods of manure application are equally crucial considerations in handling. Although not always easy, carefully assessing the nutrient qualities of both waste and soil can allow growers to return the appropriate amounts of elements and organic matter to the soil for the greatest crop yields.

According to the EPA, application of nitrogen and phosphorous in levels excess of utilization capacities results in much greater losses and pollution risk from run-off than applying at or below optimal rates. These levels vary by crop, with corn being among the highest nutrient-reaping harvests. For this reason, paying close attention to crop rotations is paramount.

“The cost associated with a growing crop is too expensive for anyone to over-apply nutrients,” elaborates Ruedinger.

“So what I would tell anyone who is questioning me is this simple statement: Would you purchase more fertilizer to apply to your lawn or garden and risk polluting the environment and have a higher cost to produce the products you harvest or the beauty of your lawn? Is that a practical approach to operating a business or your personal home budget?”

Although there are many benefits to manure fertilization, including cost savings on synthetic fertilizers, the USDA assessed that in 2006, only 5 percent of U.S. cropland used manure fertilizer. One major limiting factor is transportation, especially for those operations that do not cultivate their own fields or have widely dispersed acreage.

Semi trucks and tankers are efficient for spanning these distances with mass volumes, but compaction, road damage and public concern must be taken into consideration. As better solid separation techniques are developed, liquid waste may even be applied through normal water irrigation equipment.

And so the cycle continues – from seed-sewn fields to cud-chewing cows and back. It is what happens during this transformation that will shape the future of agriculture as a sustainable and environmentally conscious practice. PD

Holly Drankhan is a freelance writer in East Lansing, Michigan, and a student at Michigan State University.