Modelling long-term C dynamics in croplands in the context of climate change: a case study from Ohio

A simple dynamic model (CBUDGET) was developed to quantify long-term carbon (C) dynamics in croplands. By using independent datasets (on continuous wheat) from the Waite Permanent Rotation Trial (Australia) and from Northwest Ohio, the tests of its performance resulted in R-2 values of 0.85 and 0.80, respectively, between observed and simulated values. Our model suggests that the rate of residual C addition into the soil is the primary factor that controls soil organic carbon (SOC) storage for Ohio croplands under continuous corn, wheat and oats for the period 1866-1996 and continuous soybean for the period of 1924-1996. The interaction of CO2-fertilization and a temperature increase of 0.5 degreesC decreased mean SOC levels for the selected crops over the same periods. A multiple linear regression model (MLR) relating carbon dioxide (CO2) emissions to population growth, affluence and energy intensity with an R-2 of 0.99 indicates the significance of underlying causes of anticipated climate change. The MLR model thus serves to capture a more complete picture of anthropogenic sources of global climate change than considering agricultural activities only in exploring locally and regionally mitigative and preventive measures towards global climatic stability. (C) 2001 Elsevier Science Ltd. All rights reserved.