Lab-Scale Assessment of Gaseous Emissions from Laying-Hen Manure Storage as Affected by Physical and Environmental Factors

Abstract

Manure-belt (MB) and high-rise (HR) laying-hen houses are the two predominant housing types in the U.S. Compared with HR houses, MB houses have better indoor air quality and lower aerial emissions as a result of frequent (every 1 to 4 d) manure removal from the hen houses into separate manure storage. However, emissions from on-farm manure storage are integral parts of the whole-farm emissions and need to be quantified. This series of lab-scale studies assesses emission rates (ER) of ammonia (NH3) and greenhouse gases (CH4, CO2, and N2O) from stored laying-hen manure as affected by the following physical and environmental factors: air exchange rate (10 or 20 air changes per hour, or ACH), manure stacking configuration expressed as surface area to stack volume ratio (SVR at 2.5, 5, 10, or 20 m-1), air temperature (constant at 25°C or diurnal cyclic from 21°C to 32°C), manure moisture content (MC, 50% or 77%), and periodic addition of new manure to the existing stack. Results of the studies showed the following: (1) air exchange rate of 10 or 20 ACH had no apparent effects on the gaseous emissions; (2) SVR significantly affected emissions, with larger SVR leading to higher NH3 and CO2 ERs but lower CH4 ER on per kg manure basis; (3) emissions were positively related to air temperature; and (4) laying-hen manure with 77% MC had higher emissions than that with 50% MC. At the storage condition of 25°C air temperature, 20 ACH, every 2 d addition of 120 kg (5 cm thick layer) manure at 75% MC (equivalent to 2 d manure production of 682 laying hens) to the flat base area of 2.8 m2, the daily gaseous ERs per hen were 0.06 to 0.22 g NH3, 1.6 to 4.8 g CO2, and 7.4 to 32 mg CH4 (0.18 to 0.8 g CO2e). N2O concentrations from the stored manure were below the detection limit (0.03 ppm) of the measurement instrument; hence, N2O emission was omitted from the presentation.

Emission of Harmful Gases from Poultry Farms and Possibilities of Their Reduction

“…Intensive animal husbandry units, such as poultry farms, are major sources of ammonia. The reports of Wheeler et al (2006), Li et al (2008) and Li and Xin (2010) showed that 80.9% of total ammonia emissions in USA were from animal husbandry activities, of which 26.7% were from poultry.…”

“…On a per-hen basis, manure belt cage systems are generally 50% higher in capital costs than their high rise manure removing counterparts; however, manure belt systems offer considerable benefits. Manure removal from manure belt houses is less labor-intensive than the other methods, but maintenance of the belt conveyor is critical (Li, Xin, 2010).…”

“…Manure, wasted feed and feathers accumulate in the bedding, forming a nutrient-rich substrate that may subsequently become a fertiliser source. The way to manure store during the composting process affects NH 3 emissions (Li, 2006;Li, Xin, 2010). It is important that spreading the manure into thin layers would gives rise to higher emissions than stacking it into thicker layers.…”

Evaluation of EC-5 Soil Moisture Sensorsfor Real-Time Determination of PoultryManure or Litter Moisture Content

“…The estimated range of ρ for the high-rise house was 151 to 581 kg m -3 (9 to 36 lb ft -3 ). The manure ρ for the much wetter samples (Ψ ≈ 75%) from the manurebelt house was estimated to be 943 kg m -3 (55 lb ft -3 ) based on the data reported by Li and Xin (2010) for manure from the same type of manure-belt houses.…”

“…A review of literature found meager information concerning use of the soil moisture sensor for Ψ measurement of poultry litter or manure. In a study quantifying gaseous emissions from laying-hen manure, Li and Xin (2010) did use EC-20 sensors (Decagon Devices, Pullman, Wash.) to estimate Ψ of laying-hen manure and showed a good promise for the sensor.…”