Whole farm modeling: A systems approach to understanding and managing livestock for greenhouse gas mitigation, economic viability and environmental quality

Authors: AHMED, MUKHTAR - Swedish University Of Agricultural Sciences; AHMAD, SHAKEEL - Bahauddin Zakariya University; Waldrip, Heidi; RAMIN, MOHAMMAD - Swedish University Of Agricultural Sciences; RAZA, MUHAMMAD ALI - Sichuan Agricultural University

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/23/2019
Publication Date: 10/24/2019
Citation: Ahmed, M., Ahmad, S., Waldrip, H., Ramin, M., Raza, M. 2019. Whole farm modeling: A systems approach to understanding and managing livestock for greenhouse gas mitigation, economic viability and environmental quality. In: Waldrip, H.M., Pagliari, P.H., He, Z., editors. Animal Manure: Production, Characteristics, Environmental Concerns, and Management. ASA Special Publication 67. Madison, WI: American Society of Agronomy and Soil Science Society of America. p. 345-371.

Interpretive Summary: Global climate change is a hot topic worldwide, because of its potential effects on agriculture and human welfare. Livestock production is responsible for the production of greenhouse gases, including methane and nitrous oxide. Nitrous oxide is mostly derived from manure, while methane can be produced in the digestive system of cattle or in manure. As livestock production increases to meet global food demand, more and more producers may rear animals in large, concentrated animal feeding operations. This intensification can lead to increased gaseous emissions from discrete agricultural locations. It is important to understand the source and the magnitude of gas emissions from livestock systems so that effective mitigation strategies can be used, but it is generally not possible to directly measure these emissions at the farm level. This chapter authored by scientists from USDA-ARS (Bushland, TX), Swedish University of Agricultural Science, Bahauddin Zakariya University, and Sichuan Agricultural University reviews various models that can be used to estimate emissions from livestock systems. These include simple mathematical models, detailed computer-based process models, and whole farm models. Process-based modeling requires an understanding of the biochemistry that leads to gas formation. If process-based models are accurate, they can be a good option to estimate on-farm greenhouse gas losses. Whole Farm Models take into account not only the animals and manure, but also gas production during crop growth and from equipment. These types of models were recommended to estimate gas production from the various components of a working livestock system. By taking into account all components of a livestock facility, researchers can pinpoint the major routes of gas production. From there, different mitigation scenarios can be tested and potentially implemented to reduce the environmental impact of livestock at the farm level.

Technical Abstract: Climate change is a current major concern worldwide, largely due to increasing global emissions of greenhouse gases (GHG), such as carbon dioxide, methane and nitrous oxide. An increasing portion of these gases are derived from animal respiration and manure management. Increased population and rising food security concerns have promoted the practices of intensive use of resources such as CAFO (Concentrated Animal Feeding Operations). This has increased the production of GHG emissions (11% of global) from the agriculture sector. Methane, which has a 100-year Global Warming Potential (GWP) that is 28-36 times greater than carbon dioxide, primarily originates from anthropogenic activities, including animal husbandry (27%), rice cultivation (26%), fossil fuel use (28%), waste management (13%) and biomass production (9%). Livestock accounted for 14.5% of total GHG, of which 44% was enteric methane and 29% was nitrous oxide from livestock manure. Manure management is responsible for the production of 8% and 40% of methane and nitrous oxide emissions, respectively. To ensure environmental sustainability and minimization of GHG emission, adaptation and mitigation strategies are required. Accurate estimation/quantification is the first step to have a successful plan of action. Process-based modeling could be an option to quantify and evaluate emission in any system. Farm models that can efficiently simulate detailed biochemical process should be used to predict GHG emissions. This chapter reviews available models for the estimation of the environmental impact of livestock production. The use of Whole Farm Models was recommended, as they may assist with analyzing different parts of a livestock system and can be used to estimate the mitigation efficacy of different strategies to reduce GHG emissions at the farm level.