ABSTRACT
This chapter reports an estimate of carbon (C) released to the atmosphere from a spring wheat-fallow cropping system in a Major Land Resource Area (MLRA) from the central part of the northern Great Plains. It compares this estimate with an estimate of C released from cultivated soils during the period that these soils have been taken out of grassland production. Organic carbon (OC) loss is variable but generally follows a trend where an increase in the amount of OC loss is related to the length of time that soils have been cultivated. Tillage and residue management can influence the OC content of soil. The Northern Great Plains Spring Wheat Region is made up of 9 MLRA's which have climates with average annual temperature ranges from 1–9°C and average annual precipitation ranges from 250–550 mm. Crop-fallow is the predominant cropping system. Crop fallow is practiced on 46 to 74% of the land area seeded to spring wheat in the study area.
