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Title: A process-based model for cattle manure compost windrows: Model description

item Bonifacio, Henry
item Rotz, Clarence - Al
item RICHARD, TOM - Pennsylvania State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2017
Publication Date: 6/29/2017
Citation: Bonifacio, H.F., Rotz, C.A., Richard, T. 2017. A process-based model for cattle manure compost windrows: Model description. Transactions of the ASABE. 60(3):877-892. doi: 10.13031/trans.12057.

Interpretive Summary: Composting of cattle manure produced on intensive cattle production systems can emit large amounts of gaseous emissions with potential adverse impacts on human health and the environment. Process-based modeling is one approach of estimating emissions from animal production facilities without the high costs and difficulties associated with direct measurements. USDA’s Integrated Farm System Model, a whole-farm model of beef cattle and dairy production, was expanded to predict several carbon and nitrogen gaseous emissions produced during composting and the remaining nutrients in the composted manure. The revised farm model provides a tool for evaluating effects of manure management practices and climate on gaseous emissions produced during composting, along with long-term performance, economics, and overall environmental impacts of cattle production.

Technical Abstract: Composting is an alternative management practice for handling and storing manure in intensive cattle production systems. With composting, cattle manure is converted into a soil amendment with improved nutrient and physical properties and is easier to handle. Despite its benefits, composting can produce large amounts of gaseous carbon (C) and nitrogen (N) emissions that include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ammonia (NH3). A process-based model for cattle manure compost windrows was developed and incorporated into the Integrated Farm System Model (IFSM, v. 4.3), a whole-farm simulation model of crop, dairy, and beef production systems. Designed to simulate the different processes influencing C and N balances in windrows, the compost windrow model predicts changes in C (organic C, microbial C) and N (organic N, microbial N, ammonium (NH4+-N), nitrate (NO3--N)) contents in the windrow; CO2, CH4, N2O, and NH3 emissions throughout composting; and corresponding C and N losses. To increase its accuracy in simulating the different processes occurring during composting, the compost windrow model was also designed to predict environmental conditions within windrows, which include moisture content, temperature, and oxygen availability, and changes in windrow material physical properties, such as bulk and particle densities. Modeling routines and relationships of the compost windrow model are described. Evaluation of its performance in predicting windrow environmental conditions, physical and chemical properties, and gaseous emissions is documented in an accompanying paper.