The average milking dairy cow produces 140 pounds of manure daily. The Northern New York Agricultural Development Program (NNYADP) is funding research to help farmers know how and where to best use dairy manure. Dr. Quirine M. Ketterings, associate professor of nutrient management in the Department of Animal Science at Cornell University, other Cornell faculty and Cornell Cooperative Extension educators in Clinton, Essex, Franklin, Jefferson, Lewis and St. Lawrence counties are developing a critical understanding of how the nutrients in manure fertilize crops and where excess nutrients may be lost into soil, water or air.

Ketterings says, “Environmental regulations, high fertilizer prices, improved handling and storage technologies and increasing animal densities on farms demand a re-examination of best practices for manure management on farms. Achieving optimal balance requires attention. “For example,” Ketterings continues, “surface application of manure without incorporation into soil reduces the nitrogen (N) value of manure, as about half of the N in the manure will volatilize.

Due to this natural N loss, if manure is surface-applied before seeding of a corn crop at rates needed to meet N demands, it will lead to P (phosphorus) and K (potassium) accumulation over time. Since spring incorporation of manure allows for N to be used more efficiently, less manure needs to be applied. P accumulation rates are reduced, and this practice should also reduce risk of run-off losses.”

Whether or not farm fields have tile drainage also affects the best use of manure application. The research team followed National Phosphorus Project protocol for the use of rainfall simulations to measure nutrient losses in overland flow and tile lines for orchardgrass plots at the Cornell E.V. Baker Agricultural Research Farm at Willsboro. Early results based on one year of runoff data and two years of leaching data indicate that aeration of grass prior to manure application may reduce phosphorus runoff in wet years and increase infiltration without increasing nitrogen or phosphorus loss in tile lines.

Results so far suggest aeration prior to manure application might be a good alternative to surface application of manure to reduce nitrogen and phosphorus loss to tile lines; however, Ketterings cautions, more work on larger-scale plots is needed to evaluate the impact of manure incorporation on grass production and N and P dynamics. Results of a study that looked at changes in soil test P upon addition of manure and P fertilizer with soils from all of the northern New York counties indicate a relationship between extractable aluminum levels and soil test P increase.

Soils that test high in Morgan Al (soil aluminum levels greater than 50 pounds per acre) needed more phosphorus to increase soil test P levels. This is because the aluminum tightly binds with phosphorus and makes it unavailable to plants. Treatment of manure with aluminum sulfate (alum) or aluminum chloride prior to mixing with soil reduced the rate with which soil test P increased over time, especially for low Al soils.

Other ongoing research under northern New York growing conditions, soils and climate, includes a study on the impact of partial incorporation of manure into soil using an aerator for corn. Set at the most aggressive angle, the aerator can be used to mix manure with soil prior to corn planting for N conservation and odor reduction without full disturbance of and associated loss of carbon from the soil profile.

A study of the sulfur needs of alfalfa is also underway. Project results are expected to be available at winter crop meetings in early 2009. The Northern New York Agricultural Development Program is a research, education and outreach program serving the unique needs of farmers in New York’s six northernmost counties. —Excerpts from NNYADP press release