A Process-Based Ammonia Emission Model for Confinement Animal Feeding Operations—Model Development

摘要: A process-based modeling approach was used to develop a comprehensive and predictive ammonia emission model for estimating rates from animal feeding operations. The consists of farm (FEM) allocation processor (AAP) can be calculate both an individual AFO group AFOs also allows predictions different time scale resolutions. Farm Emission Model covers five species, including dairy, beef cattle, swine, layers, broilers, turkeys. For each the FEM reflects practices with regards feeding, housing, manure collection storage, land application. overall structure selected components are described in this paper. Some computer simulation results finishing swine presented. predicted variable during day over period year. INTRODUCTION Ammonia is one major gases produced emitted operations (AFO) due excretion nitrogenous compounds animals subsequent decomposition manure. On AFO, impose harms health workers at high concentrations. Off have local regional air quality impact by contributing formation particular matter acid rain nutrient enrichment surface water. Production on involve complex, dynamic biological, physical chemical processes rate influenced many factors related diet composition conversion efficiencies, handling environmental conditions. Animal efficiency affect quantity excreted properties manure, composition, biodegradability, microbial populations, oxygen content, moisture pH. Environmental conditions include temperature, wind speed, relative humidity. Accurate estimation important regulatory agencies producers. Hourly or daily these dairies needed assess their contributions dynamics that occurs areas times year so specific control strategies effectively developed. Because need, report National Research Council (NRC, 2003) highlighted need studies focus sources within operation recommended development models. collection, treatment storage structures, This paper describes AFOs. As shown Figure 1, resolutions, such as hourly, daily, monthly yearly. designed AAP categorize numbers types AFOs, management county, state, region, provide input then sum still under validation. presented separate Due space limit paper, Overall Structure employs existing models published literature new developed study. source emission, physical, chemical, biochemical reactions take place influence generation considered. Mass balances performed nitrogen, ammoniacal organic forms, they travel through four waste system (Figure 1). given growth stages 1. Model. Excretion Sub-Model sub-model calculates nitrogen response type stage animals, feed rations, productivity practices. ASAE Standard (ASAE D384) production characteristics basis developing N model. Four categories considered, weaning (5-20 kg), (20-120 gestating, lactating sows. Equations days equations must divided convert excretion. calculating dry pigs provided below definitions variables Table Nitrogen pigs: Equation (1) T R I E − = (2) 625 G CP DOF C ADFI × (3) ( ) 4 159 07 0 05 . BW FFLG DP FFLP F + Dry (4) 10000 DMD) 100 FI DM Definition pigs. Variable Description Units NE-T Total per finished pig g/finished NI-T intake NR-T DME-T BWI initial body weight kg BWF final DOFG finish DPF average dressing percent % Housing Storage Land Application Animals NH3