Economic and Environmental Assessment of Alternative Farming Systems at the Watershed Scale

Background

This study is part of a regional analysis of policy options being considered for the 1995 Farm Bill. The focus of the study is the impact of farming system alternatives on water quality in Goodwater Creek watershed. The watershed is one of five Management System Evaluation Areas (MSEA) chosen for study under the 1989 National Water Quality Initiative funded by Congress.

Objectives

1. Simulate the current (baseline) water quality in Goodwater Creek watershed with respect to sediment, nitrate, and pesticide concentrations
2. Determine water quality impacts of alternative farming systems at the watershed scale
3. Estimate the net returns for the baseline and alternative farming systems
4. Evaluate the tradeoffs between water quality and net returns

Methods

• The Soil and Water Assessment Tool (SWAT) and watershed crop history data were used to develop a baseline simulation of the current farming systems in the watershed. Five farming system alternatives for the watershed were simulated based on a range of crop yield goals, nitrogen and pesticide application rates and tillage operations.
• Ground water nitrate concentrations, surface water atrazine concentrations and sediment yields resulting from each simulation were evaluated. Net returns in the watershed were estimated for baseline and alternative farming systems.
• Farming system alternatives were ranked based on water quality and economic criteria and the best overall ranked alternative was identified. Policy implications of requiring a switch to the best-ranked farming system alternative were analyzed.

Major Findings

• The farming system alternative utilizing banded pesticide applications at 1/2 the average rate and side-dressed applications of nitrogen at a reduced rate ranks the best in terms of both water quality results and net returns to the watershed.
• A change in policy requiring a shift in farming system from current practices to reduced nitrogen/chemical inputs should consider the increased risk of reduced crop yields due to failure of the alternative weed control strategy, and the transition cost involved in acquiring the machinery and expertise for implementing the alternative.

Major Products

• An interface between ARC/INFO and SWAT was created to streamline execution of the SWAT model
• ARC Macro Language (AML) and C programs were created for extracting and summarizing output from the SWAT model

Publications

Zhou, Yan, Lynn King Heidenreich, Tony Prato, Chris Fulcher, Steve Vance and Chris Barnett. Environmental Impacts of Alternative Management Strategies in Goodwater Creek Watershed, Missouri. Proceedings: 1995 ESRI User Conference Proceedings, Palm Springs, CA, May 22-26, 1995.

Heidenreich, Lynn King, Yan Zhou and Tony Prato. Economic and Environmental Assessment of Alternative Farming Systems at the Watershed Scale, Center for Agricultural, Resources and Environmental Systems, University of Missouri-Columbia, September 1995.

Heidenreich, Lynn K, 1996. SWAT Documentation for: Environmental Assessment of Alternative Farming Systems in Goodwater Creek Watershed, Volume I: Data Sources and Formats of Model Inputs. CARES Report No. 20.

Zhou, Yan, 1996. SWAT Documentation for: Environmental Assessment of Alternative Farming Systems in Goodwater Creek Watershed, Volume II: GIS-Aided Compilation of Model Input and Output. CARES Report No. 20.

Heidenreich, Lynn K, Yan Zhou and Tony Prato, 1996. Watershed Scale Water Quality Impacts of Alternative Farming Systems, Proceedings of Watershed '96, Moving Ahead Together Technical Conference & Exposition, June 8-12, 1996, Baltimore, Maryland, p105-108.

Zhou, Yan, Lynn K. Heidenreich and Tony Prato, 1996. Watershed Water Quality Impact Assessment of Alternative Farming Systems Using SWAT. Journal of Soil and Water Conservation.(Under review)

Presentations

Zhou, Yan, Lynn King Heidenreich, Tony Prato, Chris Fulcher, Steve Vance and Chris Barnett. Environmental Impacts of Alternative Management Strategies in Goodwater Creek Watershed, Missouri. 1995 ESRI User Conference, Palm Springs, CA, May 22-26, 1995.

Zhou, Yan, Lynn K. Heidenreich, and Tony Prato, 1996. Watershed Scale Water Quality Impacts of Alternative Farming Systems, Proceedings of Watershed '96, Moving Ahead Together Technical Conference & Exposition, June 8-12, 1996, Baltimore, Maryland.

Heidenreich, Lynn King, Yan Zhou and Tony Prato, 1996. Environmental Impacts Assessment of Alternative Farming Systems at Watershed Scale Using SWAT, 51st Annual Conference of Soil and Water Conservation Society, Colorado, July 1996.

Investigators: Lynn King Heidenreich, Yan Z. Barnett and Tony Prato

Funding Amount: $63,397

Funding Source: U.S. Environmental Protection Agency through Iowa State University

Project Duration: October 1994 - September 1995