Subak, Susan (ISSE, NCARISSE, NCAR, P.O. Box 3000, Boulder, CO, 80307; Phone: 1-303-497-8117 ; Fax: 1-303-497-8125 ; Email : subak@ucar.edu)

A Comprehensive Environmental and Economic Assessment Method Applied to the Southwest Michigan Greenhouse Gas Mitigation Cropping Experiment

S. Subak *

A comprehensive assessment of net environmental and economic benefits of alternative cropping systems compared with conventional tillage is estimated for one site in southwestern Michigan. The cropping systems considered include conventional tillage, no-tillage, low-input with legume cover and an organic system with legume cover, at a site located at the Kellogg Biological Station, which is a Long Term Ecological Research site. In a study published in Science in 2000, Philip Robertson and colleagues reported their estimates of the different Global Warming Potentials related to direct and indirect carbon dioxide, methane and nitrous oxide emissions from these different cropping systems considering ten years of emissions monitoring. The present study builds on the previous greenhouse gas analysis by presenting a toxicity index for the chemical loadings on the different cropping systems related to applications of herbicides and pesticides. In addition, this study considers the nitrogen loadings associated with the different cropping systems. These three environmental effects -- greenhouse gas emissions, nitrogen loadings, and chemical loadings -- are compared with estimated economic benefits based on conventional calculations of direct input costs, crop value and yields. In this example, the three alternative cropping approaches had lower environmental and economic costs than the conventional tillage approach. While the no-tillage approach was associated with the greatest reductions in greenhouse gas emissions, the other two alternatives were associated with reduced input costs and reduced loadings of other pollutants