Estimation of ammonia emission episodes for a national inventory using a farmer survey and probable number of field working days

Abstract

S. 2007. Estimation of ammonia emission episodes for a national inventory using a farmer survey and probable number of field working days. Can. J. Soil Sci. 87: 301-313. Emissions of ammonia (NH 3 ) and odor from livestock operations, and particularly from the landspreading of manure, are an issue from many aspects. Regional and national issues include production of inhalable aerosols (PM 2.5 ), where NH 3 from agriculture is a critical precursor. This process is episodic. As a result, it is important to characterize the episodic nature of NH 3 emissions. This paper addresses the fact that weather and soil conditions can focus manure landspreading into a relatively few days each year. The Versatile Soil Moisture Budget (VSMB) was used with 30 yr of weather data on 2576 soil landscape units in Canada to estimate the number of days in each month when manure spreading would be possible. In addition, a national survey of about 3100 livestock farmers was used to quantify common practice. The stochastic information from the VSMB and the survey were applied to an NH 3 emissions model. The base case, invoked by most national NH 3 emission inventory calculations, is that emissions are uniformly distributed throughout each month. The result of our study was that daily NH 3 emission fluxes could be up to 20-fold higher in the spring and fall months when manure landspreading is common but when weather and soil conditions limit the number of days available for field work. This has direct implications for estimating the role of agricultural NH 3 on the episodic production of PM 2.5 , and this approach also has application to odor management. et les odeurs que dégagent les élevages, en particulier à la suite de l'épandage du fumier, soulèvent des difficultés à maints égards. Les problèmes régionaux et nationaux comprennent la production d'aérosols inhalables (PM 2.5 ), dont le NH 3 issu de l'agriculture est un important précurseur. Ce processus est toutefois épisodique. C'est pourquoi il importe d'en préciser la nature, notamment pour les émissions de NH 3 . Cet article se penche sur le fait que les conditions météorologiques et l'état du sol concentrent parfois les activités d'épandage sur un nombre de jours relativement restreint durant l'année. Les auteurs ont appliqué le modèle VSMB (Versatile Soil Moisture Balance, bilan hydrique polyvalent du sol) à 30 ans de données météorologiques sur 2 576 unités de pédopaysage du Canada afin d'estimer le nombre de jours par mois durant lesquels on pourrait épandre le fumier. Ils ont au ssi interrogé environ 3 100 éleveurs pour quantifier les pratiques couramment en usage. Ils ont ensuite appliqué l'information stochastique du modèle VSMB et du sondage à un modèle des émis-sions de NH 3 . Le cas d'école employé dans la majorité des calculs de l'inventaire national des émissions de NH 3 suppose une répartition uniforme des émissions durant le mois. L'étude indique cependant que le flux quotidien des émissions de NH 3 peut être 20 fois plus élevé au printemps et à l'automne, périodes d...

Farm practices survey and modelling to estimate monthly NH3 emissions from swine production in 12 Ecoregions of Canada

“…This is usually somewhat lower than the maximum capacity, since some barns will be empty or not fully occupied. The model also provides daily emission rates for landspreading days and nonlandspreading days (Sheppard et al 2007a), based on the average numbers of days each month when landspreading typically occurs. Four swine classes were itemized:…”

“…Thus, the specific knowledge gaps addressed by the farm survey and the model described in the present paper deal with the ability to compute relative NH 3 emission rates at a fine spatial resolution such as the soil land classification (SLC) polygons or uniform grids as used in atmospheric models, and temporal resolution of at least monthly. In fact, finer temporal resolution is possible with this model using the stochastic approach proposed by Sheppard et al (2007a). To develop the emission model, we tested the key hypotheses that the input data varied across Ecoregions and over a 12-mo period, which leads to the inference that relative emissions would also vary.…”

Monthly NH3 emissions from poultry in 12 Ecoregions of Canada

“…As described by Sheppard et al (2007a), weather within a region can lead to synchrony in the days when there is landspreading, especially in early spring and late fall when wet soils limit the numbers of day when field operations are possible. Table 10 and Fig.…”

“…These values can be obtained from AAFC. Additionally, the model provided daily emission rates for landspreading days and non-landspreading days (Sheppard et al 2007a), and the average numbers of days each month when landspreading typically occurs. Few poultry classes were needed:…”

“…3 illustrate. Using the estimates from Sheppard et al (2007a) of the median numbers of days per month when landspreading is possible, and assuming landspreading emissions only happen on those days, the estimates of daily emission were computed (Table 10). In April, the median is only 9.6 spreading days, yet Â15% of the annual poultry manure production is spread in April (Table 3), so that on spreading days the average emissions are estimated to be 220 kg NH 3 d…”