POLYSYS Documentation

POLYSYS is a socio-economic model of the US agricultural economy. POLYSYS is used by the USDA, Department of Energy, the EPA, and many non-governmental organizations to simulate the impact of policies that affect US agriculture. Originally created in the 1970’s, POLYSYS has been continually updated to represent the latest dynamics in the agricultural sector and to improve the modeling of landuse and environmental interactions. Past applications of the POLYSYS model include assessment of bioenergy policies, CRP payments, climate change impacts, farm bill impacts, carbon policies, and soil conservation incentives. Today POLYSYS simulates at a high spatial and temporal resolution, with landuse decisions determined at the county level and market price equilibrium determined in annual iterations for up to 50 years in the future.

Inquiries about the use of the model should be sent to Chad Hellwinckel.

Here you will find documentation of the model for researchers, users, and programmers.

Model Overview

Overview – slides
Carbon Accounting – slides
Regional Budget Estimation

Operation manuals

Biomass Simulations
Regional Version of POLYSYS

Modeling Specifics

Technical Flow
Technical Flow Map
Base Acreage
Assumed Inflation for Prices and Costs
Stochastic Model Setup
Explanation of Demand Elasticities
Baseline Expansion beyond USDA baseline
Biofuel Trade Module


Reporting of Costs in CTYouta files
Reporting of Costs in RESIDUES files

Examples of Past Applications of POLYSYS

Markel Evan, BC English, CM Hellwinckel, and RJ Menard (2018) Potential for Pennycress to Support a Renewable Jet Fuel Industry, Ecology, Pollution and Environmental science 1:121.

Hellwinckel CM, Clark C, Langholtz MH, Eaton LM (2016) Simulated Impact of the Renewable Fuels Standard on U.S. Conservation Reserve Program Enrollment and Conversion, Global Change Biology Bioenergy 8(1): pp 245–256.

U.S. Department of Energy. (2016) 2016 Billion-Ton Report: Advancing Domestic Resources for a Thriving Bioeconomy, Volume 1: Economic Availability of Feedstocks. M. H. Langholtz, B. J. Stokes, and L. M. Eaton (Leads), ORNL/TM-2016/160. Oak Ridge National Laboratory, Oak Ridge, TN. 448p. doi: 10.2172/1271651.

De La Torre Ugarte, DE and Burt English (2015) 10-year Review of the Renewable Rules Standard: Impacts to the Environment, the Economy, and Advanced Biofuels Development, White Paper, University of Tennessee, Knoxville (October 14)

Hellwinckel CM, Phillips JG (2012) Landuse Carbon Implications of a Drawdown of Ethanol Production and an Increase in Well-Managed Pastures, Carbon Management 3(1):27-38.

Schaffer HD, CM Hellwinckel, DE Ray and DG De La Torre Ugarte (2012) An Analysis of a Market-Driven Inventory System (MDIS), White Paper, Agricultural Policy Analysis Center, Department of Agricultural and Resource Economics, University of Tennessee.

U.S. Department of Energy. 2011. U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry. R.D. Perlack and B.J. Stokes (Leads), ORNL/TM-2011/224. Oak Ridge National Laboratory, Oak Ridge, TN. 227p.

English, BC, DG De La Torre Ugarte, CM Hellwinckel, KL Jensen, RJ Menard, TO West, CD Clark (2010) Implications of Energy and Carbon Policies for the Agricultural and Forestry Sectors, Publication of the 25x’25 Working Group, Washington DC, December.

Hellwinckel CM, West TO, De La Torre Ugarte DG, Perlack R (2010) Evaluating possible cap and trade legislation on cellulosic feedstock availability. Global Change Biology Bioenergy 2:278-287.

Dicks MR, Campiche J, De La Torre Ugarte DG, Hellwinckel CM, Bryant HL, Richardson JW (2009) Land use implications of expanding biofuel demand. Journal of Agricultural and Applied Economics, 41,2: 435–453.

De La Torre Ugarte DG and CM Hellwinckel (2006) Analysis of the Economic Impacts on the Agricultural Sector of the Elimination of the Conservation Reserve Program, Publication of the Agricultural Policy Analysis Center, University of Tennessee, September.

De La Torre Ugarte, DG, BC English, K Jensen, CM Hellwinckel, RJ Menard, and BS Wilson (2006) Opportunities and Challenges of Expanding the Production and Utilization of Ethanol and Biodiesel, Final Report, National Commission on Energy Policy and the Governors’ Ethanol Coalition, December.

Lin,W, P Westcott, R Skinner, S Sanford, and DG De La Torre Ugarte (2000) Supply Response Under the 1996 Farm Act and Implications for the U.S. Field Crops Sector, USDA Economic Research Service, Technical Bulletin No. (TB-1888) pp 65.

Ray, DE, JW Richardson, D De La Torre Ugarte, KH Tiller (1998) Estimating Price Variability in Agriculture: Implications for Decision Makers, Journal of Agricultural & Applied Economics 30(1):21-33.