2010 Volume 44 Issue 4 Pages 335-342
Farm-regional evaluation of soil organic carbon (SOC) dynamics for the chernozem zone in northern Kazakhstan is now vitally important for making agro-environmental policy. In this study, the author intends to evaluate spatial and temporal variation of the SOC budget and to seek alternative ways of sustainable land use in northern Kazakhstan. To achieve this final goal, this study established the following objectives: to (1) clarify the spatial patterns of soil organic matter content, (2) clarify the influence of land use on the dynamics of soil organic carbon in situ for the three differential soil classes, and (3) clarify spatial and temporal variability of SOC budget in farm-regional scale. The highest SOC content was found in the northern region and the lowest content in the southern region of the study area. Potentially mineralizable carbon (PMC) content, however, was highest in the mid-western region. Furthermore, fluctuations in CO2 emission from the soils showed a similar pattern to temperature fluctuations. Using PMC, soil temperature, precipitation and/or dryness factor, 40-80% of the variation of CO2 emission could be estimated. From farm-regional evaluation, it is concluded that the spatial and temporal variation of the SOC budget was significantly affected by the crop rotation system in the area. In addition, the fallow- and barley-based crop rotation systems accelerate SOC depletion in the study area.