Progress 07/01/05 to 06/30/07
Outputs
OUTPUTS: Under this grant, we constructed a partial temperature regulated facility to accommodate 18 200-liter barrels that can be used to measure ammonia emission from manure during storage under realistic conditions. After constructing facilities, measuring devices and validating the procedure, we conducted an experiment to determine the effect of dietary crude protein content and the addition of organic bedding on ammonia nitrogen losses during manure storage. The experiment was conducted as a complete randomized block with treatment arranged in a 2 x 2 factorial (2 manure N contents and presence or absence of wheat straw). High and low N manure was obtained from two groups of cows (160 vs. 260 DIM) assigned diets of 17 and 15% CP (DM basis), respectively. Average N intake of early and late lactation group was 678 and 528 g/c/day, respectively. Manure collected from the barn floor was thoroughly mixed, diluted with water to 10% DM and loaded in a 200-liter barrels (186 kg) with or
without mixing 22 g of coarsely chopped straw per kg of undiluted manure. Thus treatments consisted of: 1) manure from Low N intake (LN) without mixed straw; 2) manure from Low N intake (LN) with mixed straw; 3) manure from High N intake (HN) without mixed straw; 4) manure from High N intake (HN) with mixed straw. Manure was stored for 56 days in a partially temperature-controlled facility and was collected from three different depths of the barrel on days 0, 3, 6, 12, 28, and 56 of storage. Manure pH and temperature were recorded immediately after sample collection. Immediately after filling the barrels, there was a 0.2 m head space between the slurry surface and the top of the tank and a manure surface exposure of 0.27 m2. A perforated lid was placed on the top of each barrel. After sealing the barrel an anemometer was used to control air-flow in the head space. This dynamic chamber setting was used to collect gas emissions from the manure at days 0, 3, 6, 12, 28, and 56, during a
period of 2 hours with fan speed set at 2 m/s. Measurements were conducted in separate trials initiated in early May, mid-October and late October. This project was completed by Dairy Science Ph.D. candidate Matias Aguerre and allowed for the training of Jeff Schettenhelm, an undergraduate student in laboratory techniques. A photo gallery of the equipment has been made available on the PI's web site: (http://dairynutrient.wisc.edu/gallery/Measurement-of-Gaseous-Emissio ns-From-Stored-Manure). The equipment constructed under this project will be reused by colleagues at the USDA Dairy Forage Research Center in 2008.
PARTICIPANTS: Dr. Michel A. Wattiaux (project investigator); Dr. Tom Hunt, former director Plateville Pioneer Systems Research farm; Cory Weigel, herd manager, Matias Aguerre, Research Assistant; Jeff Schettenhelm, undergraduate hourly student (laboratory assistant).
TARGET AUDIENCES: Dairy farmers, nutrition consultants, environmental groups and air quality researchers.
Impacts
This trial demonstrated that significant ammonia emission reduction during manure storage can be achieved by avoiding feeding excess dietary crude protein in dairy cow diets. In addition to describing the kinetics of ammonia emission during storage, our results indicated that the reduction in pH as a result of manure fermentation (in the temperature range of 13-24 degree C) may contribute to substantial reductions in NH3-N emission. During this trial, average ambient temperature in the storage facility was 19.5, 12.9, and 13.0 degree C for replicates started in early May, mid October and late October, respectively. There was no significant effect of straw and no interactions for the reported measurements. Mean manure pH was significantly higher for HN than LN treatment (6.80 vs. 6.42, respectively). There was a sharp decline on manure pH during the first 12 days of storage, probably associated with an increase in volatile fatty acid concentration due to carbohydrate
fermentation. Manure temperature was not influenced by N intake and mixing of straw, but increased from 15.7 at day 0 to 19.6 at day 56 (P<0.01). On average NH3-N emission was reduced by 46% on LN relative to HN treatment. Emission of NH3-N was highest at day 0, declined to reach a nadir at day 6, and increased numerically thereafter. At day 56 NH3-N emissions was still 44% of day 0 emission. In this trial, NH3-N emission was correlated with manure pH (r=+0.57, n=72), but not with temperature. The positive correlation between manure pH and NH3-N emission was explained primarily by the dramatic declines in both NH3-N emission and pH during the first 6 days of storage. Initial NH3-N concentration in manure, manure handling, crust formation, fermentation pattern and length of storage had critical effects on NH3-N emission.
Publications
- Aguerre, M. A., M. A. Wattiaux, and T. Hunt. 2007. Effect of nitrogen intake, straw and days of storage on pH, temperature and ammonia emission from dairy cow manure. Electronic conference proceedings (abstract), American Dairy Science Association Joint Meeting, San Antonio, Texas. J. Dairy Sci. Vol. 90, Suppl. 1. (331-332).
- Aguerre, M. A., and M. A. Wattiaux. 2008 (forthcoming). Ammonia Emission During long-term Storage of Dairy Manure from Cows Fed Two Levels of Dietary Crude Protein.
- Aguerre, M. A., G. A. Broderick, and M. A. Wattiaux. 2008 (forthcoming). Change in Natural Abundance in N15 to Estimate Ammonia Loss of Dairy Manure During Storage.
- Aguerre, M. A., P. Barack, and M. A. Wattiaux. 2008 (forthcoming). Change in Dairy Manure Solution Chemistry and Ammonia - Ammonium concentrations During Storage.
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Progress 01/01/06 to 12/31/06
Outputs
Under this grant, we have constructed a partial temperature regulated facility to accommodate 18 55-gallon barrels that can be used to measure ammonia emission from manure during storage under realistic conditions. After constructing facilities and measuring devices, we validated the procedure and conducted an experiment to determine the effect of dietary crude protein content and the addition of organic bedding on ammonia nitrogen losses during manure storage. The experiment was designed as a complete randomized block with treatments arranged in a 2 x 2 factorial (2 dietary crude protein level and presence or absence of wheat straw bedding). At the beginning of the trial, two groups of lactating cows, a high group 120 days in milk (DIM) and producing 95 lbs/day of milk and a low group 240 DIM and producing 65 lbs/day of milk were assigned to two dietary treatments. The high group and low group were fed a diet containing 17.0 % CP and 15.0 % CP, respectively. Cows
were fed the dietary treatments 21 days before collection of the manure. The manure excreted during an 8-hour period by the lactating cows assigned to each diet was thoroughly mixed and halved. One half was directly loaded in barrels and the other was thoroughly mixed with chopped wheat straw (22 g of straw per kg of fresh manure) as recommended by the Midwest Plan Services, leading to two barrels containing manure with bedding and two without. This sampling protocol was repeated two more times in subsequent days, leading to a total of 12 barrels (three replicates per treatment). Manure was stored in the barrels for 136 days. Immediately after filling the barrels, there was a 0.2 m head space between the slurry surface and the top of the tank and a manure surface exposure of 0.27 m2. A perforated lid was placed on the top of each barrel. After sealing the barrel, an anemometer was used to control air-flow in the head space. This dynamic chamber setting was used to collect gas
emissions from the manure at days 0, 3, 6, 12, 28, 56, and 136 during a period of 2 hours with fan speed set at 2 m/s. After collecting samples from day 136, manure in each barrel was stirred for 5 minutes followed by gas emission collection for 2 hours. The sampling was repeated 36 hours later as a means to simulated the stirring that typically occurs on a farm. We studied the kinetics of ammonia emission. Peaks emission were detected at filling time (d 0) and after the final stirring (d 136), and nadir was observed between day 28 to 56. During undisturbed storage (days 56 to 136) ammonia emission remained relatively constant, but manure containing bedding had a lower emission rate that manure without bedding. This result can be explained in part by the formation of a crust that acted as a physical barrier to emission as long as the manure remains undisturbed. During this undisturbed storage period the fermentation of manure resulted in ammonia formation and build-up. After manure
was physically disturbed on d 136, ammonia emission reach a peak similar to the one measure on day 0. However, the increase in ammonia emission was greater when bedding was added to the manure compared to manure without bedding.
Impacts
Ammonia emission from manure storage follows a complex kinetics. Preliminary results indicated that an increase in dietary CP resulted in a higher emission of ammonia through out the 136 days of storage. The presence of organic bedding like wheat straw in the manure could be an important tool to reduce emission of ammonia to the environment. Mixing manure yields high peak ammonia emissions.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
The Pioneer dairy herd of the University of Wisconsin at Platteville will be used to estimate the effect of dietary crude protein (CP), the addition of bedding and length of storage on the change in manure composition and N losses. Manure will be collected from three groups of cows in the herd receiving three different levels of dietary CP. A high producing group, a low producing group and a dry cows group of cows will be fed diets containing 19.0 16.6 and 13.0 percent CP, respectively. The manure obtained from each group cows will be thoroughly mixed and halved. One half will be directly loaded in three 55 gallon barrels and the other will be thoroughly mixed with 22g of chopped straw as recommended by the Midwest Plan services (MWPS, 1995), leading to a total of nine barrels containing manure with bedding and nine without bedding. Manure will be stored for 85 days in a shed with controlled temperature and air flow. Temperature inside the shed will be monitored
hourly and maintained constant at 15 ?C. Manure samples will be collected on day 0 (manure loading into the barrels), 5, 10, 25, 40, 55, 70 and 85. Samples at three different depths will be collected with minimal perturbation of barrels content. Measurements will include pH, temperature dry matter, organic mater, total N, urea, ammonia, total and soluble phosphorus. Ammonia volatilization rate will be estimated using the circular lids supplied with the storage tanks. A centrally located fan (4 inches diameter) will drew air across the slurry surface through four inlet holes (1 inch diameter) cut at regular intervals around the perimeter of the lid. Acid-coated glass wool (soaked for 1 h in 3% tartaric acid solution in methanol) will be placed across the inlet holes to remove any ammonia from the inlet air. Ammonia concentration of the outlet air will determined by drawing a subsample of the air through an absorption flask containing dilute (0.01 M) orthophosphoric acid. The emission
rate will be calculated as the product of the concentration in the outflow air and the air flow rate through the central duct of the lid. Emission rates will be measured over a 2-h period, at the same time points used for the manure sampling. The loss of manure N during storage will be estimated by two methods. Method 1 will be a mass balance comparing the concentration of N in the manure loaded in the barrels and the concentration of N in the manure at sampling time t (using the average N concentration of the three sampling sites of the storage unit). Method 2 does not require estimates of manure loaded in the barrels, but rely solely on the change in the N to P ratio of the loaded manure and the manure recovered at the end of each sampling time. At this time the three groups of cows are on an adaptation period of the different dietary treatments. Manure will be collected and stored at the end of this 3-week period. The storage shed has been tested to verify that the desire storage
temperature will be maintained during the experiment. The modified barrels and lids have been built and some of them have been used in a pre-trial to simulate the sampling techniques of manure and air.
Impacts
This research fits in a whole farm approach to nutrient management by helping predict the losses of N to the atmosphere during storage as influenced by diet, bedding and length of storage (under mild temperature conditions). This data is important to collect because current nutrient management standards do not recognize that not all manures are created equal and thus not all manures behave equally during storage.
Publications
- No publications reported this period
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