A regional scale modeling framework combining biogeochemical model with life cycle and economic analysis for integrated assessment of cropping systems

Seyed Mohammad Hossein Tabatabaie; John P Bolte; Ganti S Murthy

doi:10.1016/j.scitotenv.2017.12.208

A regional scale modeling framework combining biogeochemical model with life cycle and economic analysis for integrated assessment of cropping systems

Sci Total Environ. 2018 Jun 1:625:428-439. doi: 10.1016/j.scitotenv.2017.12.208. Epub 2017 Dec 29.

Authors

Seyed Mohammad Hossein Tabatabaie¹, John P Bolte¹, Ganti S Murthy²

Affiliations

¹ Department of Biological and Ecological Engineering, College of Engineering, Oregon State University, Corvallis, OR 97331, USA.
² Department of Biological and Ecological Engineering, College of Engineering, Oregon State University, Corvallis, OR 97331, USA. Electronic address: Ganti.Murthy@oregonstate.edu.

PMID: 29291557
DOI: 10.1016/j.scitotenv.2017.12.208

Abstract

The goal of this study was to integrate a crop model, DNDC (DeNitrification-DeComposition), with life cycle assessment (LCA) and economic analysis models using a GIS-based integrated platform, ENVISION. The integrated model enables LCA practitioners to conduct integrated economic analysis and LCA on a regional scale while capturing the variability of soil emissions due to variation in regional factors during production of crops and biofuel feedstocks. In order to evaluate the integrated model, the corn-soybean cropping system in Eagle Creek Watershed, Indiana was studied and the integrated model was used to first model the soil emissions and then conduct the LCA as well as economic analysis. The results showed that the variation in soil emissions due to variation in weather is high causing some locations to be carbon sink in some years and source of CO₂ in other years. In order to test the model under different scenarios, two tillage scenarios were defined: 1) conventional tillage (CT) and 2) no tillage (NT) and analyzed with the model. The overall GHG emissions for the corn-soybean cropping system was simulated and results showed that the NT scenario resulted in lower soil GHG emissions compared to CT scenario. Moreover, global warming potential (GWP) of corn ethanol from well to pump varied between 57 and 92gCO₂-eq./MJ while GWP under the NT system was lower than that of the CT system. The cost break-even point was calculated as $3612.5/ha in a two year corn-soybean cropping system and the results showed that under low and medium prices for corn and soybean most of the farms did not meet the break-even point.

Keywords: Crop model; DNDC; ENVISION; Integrated model; Life cycle assessment.