Many dairy farmers have surplus manure and many dairy farmers stack manure in fields. Composting and sale of the compost is one method to reduce surplus manure on dairy farms. Field stacking of manure is not a recommended practice, but the stacking will not likely stop for a long time for many reasons. Making compost from manure and stacking manure in fields are both considered environmentally risky because of the potential for loss of nutrients to surface and ground water. For this reason, current guidelines from NRCS do not recommend stacking of manure in fields unless the manure is contained in some manner, and current regulations at the CT Department of Environmental Protection for compost operations require an expensive gravel or concrete pad with collection of the runoff. The problem is that it is too expensive to establish a composting operation or to stack manure in fields if the farmers need to meet current environmental guidelines and regulations. Methods to stack manure or create compost from manure that minimize environmental problems are needed for more sustainable dairy farms.
We propose to develop methods to make compost and stack manure that minimize the amount of nutrients that escape from the compost windrows and manure stacks. Making compost and stacking manure are the same operations because to create a stack of manure requires the addition of carbon in some form to make the manure into a stack. Without the addition of carbon, manure when placed in a field is called a self-leveling pancake, not a stack.
Building on the ideas of several Connecticut dairy farmers, the objective of this project was to develop methods to stack fresh barnyard manure that minimize the amount of nutrients that escape from the manure stacks.
We measured the ammonium concentration in the soil underneath and nearby the manure piles, with at least three treatments in each experiment at each farm. Results from the experiments on the Collins and the Staebner farm last year suggest that covering a pile with a carbon material with a low nutrient content, such as partially decomposed leaves or strawy horse manure, or placing a material underneath the pile that has a great capacity to capture ammonium, such as finished compost, works well to minimize leaching of ammonium. At each farm we will have at least 3 treatments: one treatment will cover the piles with a low-nutrient content material, another treatment will place the pile on top of a material that adsorbs ammonium, and the third treatment will have both a cover and adsorbing material underneath the piles.
Contols for the experiments include manure stacked without any cover of carbonaceous material or placement of an adsorbing material underneath the pile. The amount of carbon mixed with the manure was be the same as the amount mixed with the treatment piles. The second control was in an area of the field adjacent to the experimental piles that has not had any manure or compost stacked on it in the past. The second control allows the measurement of background concentrations of ammonium in the soil.
The piles are static; no turning of the piles will be performed. The piles remain in the field for about six months. Soil samples are collected one to two days before the piles are created from designed areas where the piles are located. Samples are also collected the day the piles are removed from the field. Samples are collected from the surface two-foot of soil. The areas sampled are underneath each pile and from the control area where no manure or compost was stacked. These samples are then analyzed for ammonium and nitrate.
Four new farmers were recruited to participate in on-farm studies. Each of these farmers made 8 (2 replications of 4 treatments) test stacks with farmyard manure in the fall of 2003. They used available old hay as a carbon source for layering above and below the stacks. As a control, manure was also stacked, without layering of any organic material, a typical farmer practice. Prior to stacking, soil was sampled below and immediately adjacent (down slope) of the area to be occupied by each stack. A background area where no manure or compost was stacked was also sampled. The piles remained in the field for 6-7 months. They were not turned. In spring 2004, the piles were removed and the soil sampled again. All samples were collected from the surface 1-foot of soil and were analyzed for ammonium and nitrate. Pre-stacking values were compared with post -stacking values as indicators of possible loss of nutrients or other soluble compounds from the treatment stacks.
Results varied with the initial quality/age/nutrient content of the manure used in the stacks, but overall trends were similar. The farm that used fresh manure in its stacks had similar results to the farmers that initiated the experiment. The layering of old hay above and below a stack of dairy manure appears to greatly reduce the loss/movement of ammonium and nitrate from the stacks; nearly to background levels. Layering an organic material either above or below a stack also reduces nutrient movement form the stack to the soil, but not to the same extent. Ammonium levels appear to be more influenced by the use of a layer of organic material than nitrate. Stacking manure without any layer(s) of organic material results in elevated concentrations of soil nitrate and ammonium, presumably that has moved from the manure stack.
The on-farm trial results were presented at a field day at Russ Wheeler’s compost site in western Connecticut in September 2004. About a dozen farmers and agency field personnel attended. Results of these experiments have been presented by Tom Morris at meetings for dairy farmers held each year in the eastern and western sections of Connecticut and at the New England CCA meeting at Portsmouth, NH in February 2004. The results were also discussed and shared at the annual Farmer Research Group meeting in February 2005. One of farmers who participated in the on-farm trials discussed his results at a field day held at the University of Connecticut’s Research Station in Storrs on March 29, 2005.
The farmer showed the results below, which are typical for the results from all sites.
Treatment Before stacking After stacking
soil ammonium-N concentration (ppm)
No Pile 11.6 15.7
Manure 18.4 75.9
Compost(base) 11.1 28.5
Leaves (top) 15.0 89.7
Compost/Leaves 12.5 13.7
Soil samples collected from the surface 12-inch layer immediately before stacks created on December 7, 2002 and on the day of removal of the stacks on June 27, 2003.
The treatments consisted of: 1) an area in the field where no manure was piled, 2) dairy manure stacked by the farmer in a pile about 20 feet long and 12 feet wide, 3) dairy manure stacked on a 1-foot thick base of finished compost, 4)dairy manure stacked on the ground with a 1-foot layer of paritally decomposed leaves on top of the pile, and 5) dairy manure stacked on a compost base and with leaves on top. It is obvious from these results that the treatments had a large effect on the loss of ammonium from the piles.
We designed a set of 12 pads (10 foot by 14 foot) for stacking manure with the help of the farmers in this group. The pads allow the collection of all the leachate and runoff from the manure piles. We stacked 12 piles of layer chicken manure in the pads on November 30, 2005. We had the same treatments as noted in the farmer’s experiement above except we did not have a no manure pile treatment. Each treatment was replicated three times. We collected samples of the runoff from each of the piles. The results from the experiment for nitrogen lost from the piles are shown below. The values are for eight runoff events from December 1, 2004 until March 6, 2005.
total N NH4-N NH4-N
(% of total)
—– lb/pad —– %..
Manure 22.6a 13.1a 57.7a
Leaves 12.1b 7.6b 63.1a
Compost 13.0b 7.8b 59.8a
&leaves 5.8c 3.7c 63.7a
These results confirm that compost as a base to isolate the manure piles from the ground significantly reduces the amount of nitrogen lost from the pile, and the placement of leaves on the top of the piles also significantly reduces the amount of nitrogen lost. The best results were measured when both compost and leaves were used. Using both leaves and compost reduced the amount of total N lost by 74%.
A number of farmers have expressed interest in using leaves, hay or other materials with low amounts of soluble nitrogen to minimize the loss of nutrients from manure piles. The farmers would like to have NRCS provide a cost-share for buying the compost or leaves for treating their manure piles. Many NRCS employees have atttended our field days and education sessions. We have had discussions with NRCS about developing an interim standard for field stacking of manure. We will present our complete results to the State Technical Committee in the fall of 2005 for discusssion about developing an interim standard.
Education & Outreach Activities and Participation Summary
No publications have been developed from this project. We will be submiting a manuscript to the Journal of Environmental Quality showing the results of the manure stacking experiments. Numerous outreach events were completed as described in the Results and Discussion section.
No economic analysis was completed.
Farmers have not adopted this method of reducing losses of nutrients from manure stacks because they plan to work with NRCS and Extension to develop an interim standard for manure stacking, which would allow cost-sharing of the expense to buy the materials low in soluble nutrients like compost and leaves. If an interim standard can be developed, the expectation is that some small (50 to 150 head) dairy farms would adopt this practice instead of building a manure storage lagoon.
Areas needing additional study
Our results from the replicated studies of losses of nutrients from manure stacks were completed with chicken manure. Less loss of nutrients would be expected from stacks of dairy manure. Replicated studies should be completed using the same treatments of compost as a base and leaves as a roof to minimize losses of nutrients from stacks of dairy manure.