Abstract
Cattle and sheep systems in Uruguay and worldwide are challenged to reduce their environmental footprint while increasing efficiency and production. To achieve this challenge, user-friendly tools are needed that can translate research findings into practical information that could improve decision making by farmers and advise different stakeholders. Despite this, there are a limited number of applied environmental models in other countries and they are typically based on productive, high-quality pasture/crop-feed systems with relatively high inputs. In contrast, cattle and sheep production in Uruguay is largely associated with extensive grazing systems on unique natural grassland systems of relatively poor feed quality and often with no nutrient inputs in fertilizers. Thus, there is a need for a model that can take account for these types of systems and bring together relevant country-specific data to provide information of relevance for Uruguay. The EMAG (Evaluación Medio Ambiental Ganadera) model accounts for multiple environmental and resource use indicators of nutrient (nitrogen and phosphorus) balances and losses, greenhouse gas emissions and use of fossil energy. Results are provided on a per-hectare and per-kg product basis. This decision support tool for cattle and sheep farmers systems is based on life cycle assessment (LCA) methodology from “cradle-to-farm gate” for all resources use indicators. It uses national parameters and in case of lack of information is supplied from international research in pastoral systems. The model use for environmental methodology tier 2 animal energy model to account for key animal productivity and management practices. EMAG is a user-friendly model that requires basic information for a farm system divided into land use (forage types used uniquely for natural grassland in Uruguay), animal management (beef cattle and sheep), farm inputs (fertilizers, supplementary feeds, seeds and agrochemicals) and fossil energy (fuel and electricity) used in the system. EMAG can help to identify hot-spots of emissions and resource use, as well as to evaluate changes over time. In addition, it can be used to test cattle or sheep management practices or evaluate mitigation options within the system. By providing multiple indicators, EMAG can be used to provide information to avoid “trade-offs” between environmental impacts when assessing future options. As an example of usability, the paper reports a case study which showed potential benefits of improving environmental efficiency and note interesting result around negative P balance when increase productivity in a system. In summary, EMAG is a decision-support tool developed with the objective of evaluating the environmental performance of cattle and sheep systems, that would help farmers in decision making and different stakeholders according to their interest.
Highlights
The environmental impacts of livestock systems have become an important issue of public and scientific debate worldwide, for more than a decade(1)
There are some practical models that can be used in livestock production, such as Overseer in New Zealand(9) and Holos in Canada(10), which are based on biophysical models to evaluate changes in production and estimate environmental emissions
EMAG methodology for analyzing environmental emissions is based on using life cycle assessment (LCA), with the system boundary defined from “cradle-to-farm gate”(15)
Summary
The environmental impacts of livestock systems have become an important issue of public and scientific debate worldwide, for more than a decade(1). There are some practical models that can be used in livestock production, such as Overseer in New Zealand(9) and Holos in Canada(10), which are based on biophysical models to evaluate changes in production and estimate environmental emissions This limited number of applied environmental models are based on productive, high quality pasture/crop-feed systems with relatively high inputs. This paper gives an overview of why a national model for cattle systems is needed and the specification of a complete animal biology model with modules for estimating resource use and environmental emissions It includes the variables, equations and parameter values that are used in the tool, the validation of this model with international models, and illustrates how it works using a case study. Machinery activities are entered on an area basis to estimate indirect fuel use
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