Analysis of Factors Controlling Soil Organic Matter Levels in Great Plains Grasslands

Abstract

We analyzed climatic and textural controls of soil organic C and N for soils of the U.S. Great Plains. We used a model of soil organic matter (SOM) quantity and composition to simulate steady‐state organic matter levels for 24 grassland locations in the Great Plains. The model was able to simulate the effects of climatic gradients on SOM and productivity. Soil texture was also a major control over organic matter dynamics. The model adequately predicted aboveground plant production and soil C and N levels across soil textures (sandy, medium, and fine); however, the model tended to overestimate soil C and N levels for fine textured soil by 10 to 15%. The impact of grazing on the system was simulated and showed that steady‐state soil C and N levels were sensitive to the grazing intensity, with soil C and N levels decreasing with increased grazing rates. Regional trends in SOM can be predicted using four site‐specific variables, temperature, moisture, soil texture, and plant lignin content. Nitrogen inputs must also be known. Grazing intensity during soil development is also a significant control over steady‐state levels of SOM, and since few data are available on presettlement grazing, some uncertainty is inherent in the model predictions.

Effects of dispersal and selection on stochastic assembly in microbial communities

“…We varied leaf chemistry by altering the lignin to nitrogen (N) ratio. We chose this metric because it is a wellestablished control on microbial activity and litter decomposition (Parton et al, 1987), and because we know that the ability of microbes to degrade different substrate lignin/N varies depending on specific traits they posses (Paul and Clark, 1997). Lignin/N ranged from 3.9 to 48.6 (see Supplementary Table S2 for Parameters not listed follow those in Table 1 of Allison (2012).…”

Carbon dynamics and land-use choices: building a regional-scale multidisciplinary model

“…We have elected to use the well-established ecosystem model CENTURY. This model, developed at Colorado State University (Parton et al, 1987), simulates C, N, P, and S cycles in various ecosystems, including pastures, forests, crops, and savannas, and can model the impacts of management practices such as fertilization, and cultivation, as well as natural disturbances such as fire and hurricane (Parton et al, 1987(Parton et al, , 1993. This model has also been tested extensively against field measurements from various ecosystems around the world (e.g., Parton et al, 1993;Schimel et al, 1994;Smith et al, 1997) and used for biogeochemical simulation purposes at the regional, continental, and global scales (e.g., Schimel et al, 1994;VEMAP, 1995;Schimel et al, 1997).…”

Carbon benefits of wolfberry plantation on secondary saline land in Jingtai oasis, Gansu – A case study on application of the CBP model

“…A number of models have been used to estimate biomass carbon, soil organic carbon (SOC) stocks, and carbon emissions including the Century Model (Parton et al, 1987), Roth C (Jenkinson et al, 1992) and DNDC (Li, 2002). Some empirical and allometric equations and computer models combined with national forest inventory data are also employed to estimate carbon sequestration and dynamics of forest ecosystems in China (Xu, 1995;Huang et al, 2012;Zhang et al, 2002).…”