LORINQUER, E.1, CHARPIOT, A.1, ROBIN, P.2, LECOMTE, M.2
1 Institut de l’Elevage, Monvoisin BP 85225, 35652 LE RHEU Cedex, France;
2 INRA UMR-SAS, 65 Rue de Saint Brieuc, 35042 Rennes, France
ABSTRACT: In France, 46% of ammonia national emissions come from dairy and beef cattle farms (CITEPA, 2010). Storage represents nearly 13% of nitrogen losses (as ammonia) of the livestock in France, but only few studies on it. This study focus on solid manure that represent more than 80% of national cattle manure. Different practices have been tested to see their effects on gaseous emissions (CO2, CH4, NH3, N2O, H2O): control heap (cont.), covered heap (cov.), compacted covered heap (cov.+cont.). Around five tons of solid manure per heap have been stored on a platform, temperatures have been followed at different heights (30, 60 and 90 cm).
Gaseous emissions were followed during 48 hours every week for 14 weeks. Gas concentrations were measured at entry and exit of dynamic chamber with an infrared photoacoustic analyser (INNOVA 1412). Ventilation rate was controlled with Fancom mechanical fan. This study show that most of emissions N-NH3, N-N2O and C-CH4 occurred during the first month, emissions are respectively from 4 to 12%, 0.075 to 0.15%, 0.3 to 3% of initial N and C present in the heap. N emissions of deep litter heaps are mainly on N2 form. Compaction leads to a higher CH4
emissions (10 times).
Keywords: GHG, NH3, solid manure, cattle, storage
INTRODUCTION: From the environmental point of view, ammonia emissions are partly responsible for acidification and eutrophication. In France, agriculture contributes 97% to national ammonia emissions which 46% comes from bovine farms (CITEPA, 2010). Different regulations at international, European and national levels have been established to limit particulate emissions, including ammonia, and sign up for part in the National Health and Environment Plan (NESP). As part of the proposed measures to reduce gas emissions in agriculture, it is necessary to pay attention to their feasibility from the point of view of their environmental efficiency and of their relevance at the farmer scale. Emissions from storage, which represent nearly 13% of nitrogen losses (as ammonia) from the bovine livestock operation, has however been little studied in France. This is particularly the case of cattle solid manure whose emissions are ignored while 68.7 million tons of cattle manure are produced each year in
1. MATERIAL AND METHODS
1.1. Farm and manure characteristics: The solid manure studied comes from a Pays de la Loire dairy farm. During accumulation period, there were 69 Holstein dairy cows in 400 m² straw based loose housing (10 kg of straw/cow/day). Dairy cows were fed with maize silage, grass silage and concentrates (respectively 38 kg, 17 kg, 7 kg of raw matter per cow), and they produced 28 kg milk.day-1.cow-1 during the accumulated period with an average of 6 months lactation stage.
After removal from the barn, 5 tons of solid manure per heap have been stored on a platform from 13/02/2013 to 22/04/2013. Three storage modalities of this solid manure have been tested at the experimental farm of Derval: (i) Control (Cont.) manure stored in a heap, (ii) Covered (Cov.) with a polypropylene cover (Gangloff® Toptex) and (iii) Covered + compacted (Cov. + Comp.) with tractor at storage.
Figure 1: Heap shape at the beginning of storage from left to right : Cont., Cov, Cov. + Comp.
1.2. Gaseous emissions: Temperatures have been followed at different heights (30, 60 and 90cm) with thermocouples linked with a CR3000 (Campbell Scientific). Gaseous emissions were followed during 2 days (48 hours) every week for 11 weeks with dynamic chamber systems (Greenhouse structure covered by a plastic cover usually used to cover maize silage). Gas concentration were measured at entry and exit of dynamic chamber with an infrared photoacoustic analyser (INNOVA 1412). Ventilation rate was controlled with Fancom mechanical fan, and punctually controlled anemometer (TSI 8470, TH-industrie, Paris). During 1 week, from 27/02 to 6/03/13, heaps have been covered and SF6 tracer gas has been introduced at entry to estimate and validate the ventilation rate of the fan. All along the trial, air entry size and ventilation rate have been adapted in order to keep a sufficient difference between entry and exit air concentrations to calculate the gradient concentration ([Gasoutlet]-[Gasinlet]). Leachates were collected, weighted and analysed regarding rainfall during all the storage period. Gas emissions were calculated by multiplying concentration gradients and ventilation rates.
Emissions between, two measurements points have been estimated with a linear interpolation.
2. RESULTS AND DISCUSSION: Ammonia emissions range from 4 to 12% total nitrogen originally present in the heap (table 1), probably related to the low ammonia nitrogen content of this type of effluent (11-34% of TAN – “total ammoniacal nitrogen” – TAN representing 35% of initial nitrogen). N2O emissions ranged between 0.08 and 0.2% of total nitrogen initially present. Liquid losses of nitrogen (nitrate, ammonia) were less than 1% of the initial total nitrogen. The decrease in nitrogen of deep litter cattle manure occurs mostly in the form of dinitrogen (N2-N ; 24-28% of the initial total nitrogen for the control and the covered pile, and 4% for the compacted treatment).
Emission factors and air quality
Table 1. Number of observations (n), emission factors EF (in % of TAN applied) and range in the data for various liquid manure application methods.
Treatment Cont. Cov. Cov. + comp.
Mass Manure initial mass Kg 5060 5020 5100
Manure final mass Kg 3440 2774 3824
Gas losses N-NH3 %initial_mass_totalN 12 7 4
N-N2O %initial_mass_totalN 0.1 0.08 0.2
N-N2 %initial_mass_totalN 24 28 4
C-CH4 %initial_mass_totalC 0.4 0.3 3
C-CO2 %initial_mass_totalC 41 26 27
Leachate losses Total N %initial_mass_totalN 0.7 0.6 0.7
This study shows that NH3-N, N2O-N and CH4-C emissions occur predominantly during the first month of storage for deep litter heap (FTC), respectively in the range of 97 to 100%, 41 to 56%
and 82 to 90% depending on the treatment (Figure 1).
Figure 1. Cumulative and daily emissions during storage period of the 3 treatments (cont., cov. And cov.+comp.) of NH3-N (left) and CH4-C (right).
The treatments studied in this project confirmed the hypothesis of ammonia emission reductions by covering or compacting (Petersen & Sommer, 2011). The uncertainty on emission reduction (in % of initial total nitrogen) was less than 6%, but remained high considering the uncertainty about the initial composition of manure (above 20%) and the repeatability of pile setting up (complex geometrical shape, lack of turning equipment). Covering the pile induced a decrease in biological activity by limiting humidification from rain. This result should be confirmed with further measurements covering the variability of pile setting and climates (rainfall). Regarding GHG emissions, covering the pile did not reduce emissions. On the contrary, the compaction has
linked to farm practices (feed ration, type and amount of litter, type of housing, grazing, animal productivity,…), so further investigation are required to have an overview of diversity at national scale on the whole manure management chain.
Acknowledgements. Acknowledgements, to the partners: IRSTEA Rennes, INRA UMR SAS, Derval experimental farm and the funder ADEME.
REFERENCES:
CITEPA, 2010. Inventaire des émissions de polluants atmosphériques en France – Séries sectorielles et analyses étendues – Format SECTEN, 247p.
Petersen S. O., S. G. Sommer, 2011. Ammonia and nitrous oxide interactions: Roles of manure organic matter management. Animal Feed Sci. and Technol. 166– 167, 503– 513.
Emission factors and air quality
EVALUATION OF GHG AND AMMONIA IN THE PROCESS OF COMPOSTING CHICKEN CARCASSES