Location: Soil and Water Management Research
Title: Manure application under winter conditions: Nutrient runoff and leaching losses Authors
Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2011
Publication Date: June 24, 2011
Citation: Williams, M.R., Feyereisen, G.W., Beegle, D.B., Shannon, R.D., Folmar, G.J., Bryant, R.B. 2011. Manure application under winter conditions: Nutrient runoff and leaching losses. American Society of Agricultural and Biological Engineers. 54(3):891-899. Interpretive Summary: Land application of manure in northern states, where winters include freeze-thaw cycles and snow accumulation and melt, continues to be controversial. The benefits of winter manure application include reduced soil compaction, reduced need for large manure storage structures, and more available time. Losses of nutrients from winter application are dependent on soil conditions and snow cover at the time of and after application. This study was conducted to determine the relative losses of nitrogen and phosphorus when manure is applied prior to snowfall, between snowfalls, and on top of the snow pack. Soil cores taken in 6-in. diameter PVC pipes were encased in sand boxes and frozen at the upper surface to mimic field conditions. Dairy manure was applied to the soil prior to, during, and after an artificial snowfall. The samples were exposed to a 4-day snowmelt event under natural conditions. Water samples from the runoff water and leachate were collected and analyzed. Inorganic nitrogen losses were highest for the samples with manure under the snow. On the contrary, dissolved reactive phosphorus losses were highest for the samples with manure on top of the snow. After the snowmelt, the samples were subjected to an artificial rainfall. Inorganic nitrogen losses were much less than for the snowmelt and followed the same trend. Dissolved reactive phosphorus losses were in reverse order of the snowmelt event and the sum of phosphorus losses for the two events was similar whether the manure was under, in the middle of, or on top of the snow pack.
Technical Abstract: Winter application of manure is commonly practiced and potential nutrient losses are difficult to predict. This study was conducted in order to determine nutrient losses via surface runoff and subsurface leachate from winter-applied manure based on its relative placement with respect to snow. A laboratory soil thermal cycling system containing PVC lysimeters encased in sand and a commercially-available heating cable was used to replicate freeze-thaw field conditions. Dairy manure was applied either before, midway through, or upon completion of an artificial snowfall. Runoff and leachate were collected throughout a 4-day snowmelt event and subsequent rainfall simulation. During the snowmelt, inorganic-nitrogen losses of 76.4, 113.8, and 205.3 µg/cm2 were observed for the manure-on-top-of-snow, manure-in-between-snow, and manure-under-snow treatments, respectively, while dissolved reactive phosphorus (DRP) losses of 2.4, 1.5, and 0.7 µg/cm2 were seen. Inorganic-nitrogen losses during the rainfall simulation were significantly less than the snowmelt; however, the losses followed a similar trend. Unlike the snowmelt, DRP losses in surface runoff from the rainfall simulation were 1.1, 1.2, and 2.8 µg/cm2 for the manure-on-top-of-snow, manure-in-between-snow, and manure-under-snow treatments, respectively. This research shows that the relative placement of manure with respect to snow plays a significant role in the fate of N and P from winter-applied manure.