Improved modeling of soil organic carbon in a semiarid region of Central East Kazakhstan using EPIC
- First Online:
- 173 Downloads
Inappropriate land use and soil mismanagement produced wide-scale soil and environmental degradation to the short-grass steppe ecosystem in the semiarid region of central east Kazakhstan. A limitation for determining the impacts of land use changes on soil organic carbon (SOC) is the dearth of information on SOC stocks under the predominant land uses in the region. Here we used the Environmental Policy Integrated Climate (EPIC) model to study long-term impacts of land use changes and soil management on SOC to a depth of 50 cm during 1955–2030, in degraded agricultural lands of central east Kazakhstan. Simulated land uses were: native rangeland vegetation, wheat (Triticum aestivum L.), wheatgrass (Agropyron cristatum L.), and abandoned croplands. The EPIC model was initialized with soil properties obtained from a soil map of the study area. Data on crop management, fertilizer application and tillage practices were gathered from local expert knowledge. Simulations were performed for each polygon on a land use classification map, resulting in 4661 simulations. Our results showed that simulated SOC explained 50% of the variation in measured SOC. Of the 1.38 million hectares in the study area, 78% were under native vegetation, 3% cultivated to wheat, 8% on wheatgrass, and 11% were abandoned croplands in 2005. If land use remained constant, total stock of SOC would decrease at an annual rate of 723 kg C ha−1. However, if best management practices are implemented, resulting in reallocation of land use according to the land capability with abandoned croplands being converted to reduced-tillage wheat or wheatgrass, total stock of SOC would increase to an equivalent of 4700 kg C ha−1 yr−1. Combining land use classification and soil maps with EPIC, proved valid for studying impacts of land use changes and management practices on SOC; an important aspect of this approach is the ability to scale up site-specific SOC to the region. With the available data, EPIC produced relatively accurate results but more data on spatial and temporal variation in SOC are needed to improve model calibration and validation.
KeywordsEPIC model Kazakhstan steppe soil organic carbon
Unable to display preview. Download preview PDF.
- Gassman P.W., Williams J.R., Benson V.W., Izaurralde R.C., Hauck L.M., Jones C.A., Atwood J.D., Kiniry J.R., Flowers J.D. (2004) Historical development and applications of the EPIC and APEX models (ASAE Paper No.042097), ASAE, St. Joseph, MI.Google Scholar
- Hargreaves G.H., Samani Z.A. (1985) Reference crop evapotranspiration from temperature, Appl. Eng. Agric. 1, 96–99.Google Scholar
- Izaurralde R.C., Rosenberg N.J., Brown R.A., Thomson A.M. (2003) Integrated assessment of Hadley Center (HadCM2) climate-change impacts on agricultural productivity and irrigation water supply in the conterminous United States: Part II. Regional agricultural production in 2030 and 2095, Agric. For. Meteorol. 117, 97–122.CrossRefGoogle Scholar
- Kaser M. (1997) The economics of Kazakhstan and Uzbekistan. London: The Royal Institute of International Affairs.Google Scholar
- McCauley M. (1976) Khrushchev and the development of Soviet agriculture: The Virgin Land Programme, Holmes & Meier, New York, pp. 1953–1964.Google Scholar
- United States Geological Survey (2007) Seamless Data Distribution System [Online]. Available at http://seamless.usgs.gov (verified 23 July 2007).
- Wang X., He X., Williams J.R., Izaurralde R.C., Atwood J.D. (2005) Sensitivity and uncertainty analyses of crop yields and SOC simulated with EPIC, Trans. ASAE 48, 1041–1054.Google Scholar