Development and evaluation of an integrated simulation model for assessing smallholder crop–livestock production in Yucatán, Mexico

Mixed farming systems constitute a large proportion of agricultural production in the tropics, and provide multiple benefits for the world’s poor. However, our understanding of the functioning of these systems is limited. Modeling offers the best approach to quantify outcomes from many interacting causal variables in these systems. The objective of this study was to develop an integrated crop–livestock model to assess biophysical and economic consequences of farming practices exhibited in sheep systems of Yucatán state, Mexico. A Vensim™ dynamic stock-flow feedback model was developed to integrate scientific and practical knowledge of management, flock dynamics, sheep production, partitioning of nutrients, labor, and economic components. The model accesses sheep production and manure quantity and quality data generated using the Small Ruminant Nutrition System (SRNS), and interfaces on a daily basis with an Agricultural Production Systems Simulator (APSIM) model that simulates weather, crop, and soil dynamics. Model evaluation indicated that the integrated model adequately represents the complex interactions that occur between farmers, crops, and livestock.

Research highlights
► An integrated crop–livestock simulation model was developed to assess biophysical and economic consequences of farming practices exhibited in sheep systems of Yucatán state, Mexico.
► The model uses existing crop and soil (APSIM) and animal nutritional (SRNS) modeling software packages, linked by Vensim™, an icon-based modeling software package.
► The strength of this modeling approach is the combination of harnessing the power of well established biophysical modeling packages with the flexibility to simulate very specific and unique crop–livestock systems.