The turnover of organic carbon in subsoils. Part 2. Modelling carbon turnover

A new model, RothPC‐1, is described for the turnover of organic C in the top metre of soil. RothPC‐1 is a version of RothC‐26.3, an earlier model for the turnover of C in topsoils. In RothPC‐1 two extra parameters are used to model turnover in the top metre of soil: one, p, which moves organic C down the profile by an advective process, and the other, s, which slows decomposition with depth. RothPC‐1 is parameterized and tested using measurements (described in Part 1, this issue) of total organic C and radiocarbon on soil profiles from the Rothamsted long‐term field experiments, collected over a period of more than 100 years. RothPC‐1 gives fits to measurements of organic C and radiocarbon in the 0–23, 23–46, 46–69 and 69–92 cm layers of soil that are almost all within (or close to) measurement error in two areas of regenerating woodland (Geescroft and Broadbalk Wildernesses) and an area of cultivated land from the Broadbalk Continuous Wheat Experiment. The fits to old grassland (the Park Grass Experiment) are less close. Two other sites that provide the requisite pre‐ and post‐bomb data are also fitted; a prairie Chernozem from Russia and an annual grassland from California. Roth‐PC‐1 gives a close fit to measurements of organic C and radiocarbon down the Chernozem profile, provided that allowance is made for soil age; with the annual grassland the fit is acceptable in the upper part of the profile, but not in the clay‐rich Bt horizon below. Calculations suggest that treating the top metre of soil as a homogeneous unit will greatly overestimate the effects of global warming in accelerating the decomposition of soil C and hence on the enhanced release of CO2 from soil organic matter; more realistic estimates will be obtained from multi‐layer models such as RothPC‐1.

[1]  P. Poulton,et al.  The turnover of organic carbon in subsoils. Part 1. Natural and bomb radiocarbon in soil profiles from the Rothamsted long‐term field experiments , 2008 .

[2]  C. Post,et al.  Organic carbon stocks in the Russian Chernozem , 2006 .

[3]  Budiman Minasny,et al.  Prediction and digital mapping of soil carbon storage in the Lower Namoi Valley , 2006 .

[4]  E. Davidson,et al.  Temperature sensitivity of soil carbon decomposition and feedbacks to climate change , 2006, Nature.

[5]  Bjørn Molt Petersen,et al.  CN-SIM—a model for the turnover of soil organic matter. I. Long-term carbon and radiocarbon development , 2005 .

[6]  Michael J. Rogers,et al.  Long-term sensitivity of soil carbon turnover to warming , 2005, Nature.

[7]  P. Cox,et al.  Global climate change and soil carbon stocks; predictions from two contrasting models for the turnover of organic carbon in soil , 2005 .

[8]  H. Meserve,et al.  Twenty-five years , 1986, Journal of Religion and Health.

[9]  D. Greenwood,et al.  The deficiency of the ‘economic optimum’ application for evaluating models which predict crop yield response to nitrogen fertiliser , 1986, Fertilizer research.

[10]  X. Daia,et al.  Black carbon in a temperate mixed-grass savanna , 2005 .

[11]  K. Paustian,et al.  Estimating Turnover of Soil Organic Carbon Fractions Based on Radiocarbon Measurements , 2005, Radiocarbon.

[12]  P. Vitousek,et al.  The Influence of Nutrient Availability on Soil Organic Matter Turnover Estimated by Incubations and Radiocarbon Modeling , 2005, Ecosystems.

[13]  J. Six,et al.  Estimating vital statistics and age distributions of measurable soil organic carbon fractions based on their pathway of formation and radiocarbon content. , 2004, Journal of theoretical biology.

[14]  P. Brookes,et al.  Distribution of microbial biomass down soil profiles under regenerating woodland , 2004 .

[15]  C. Masiello,et al.  Weathering controls on mechanisms of carbon storage in grassland soils , 2004 .

[16]  D. Powlson,et al.  Turnover of Nitrogen-15-Labeled Fertilizer in Old Grassland , 2004 .

[17]  N. Buchmann,et al.  A new model for soil organic carbon turnover using bomb carbon , 2004 .

[18]  B. Campbell.  Selected climatic data for a global set of standard stations for vegetation science , 2004, Vegetatio.

[19]  J. van der Plicht,et al.  Mean residence time of soil organic matter associated with kaolinite and smectite , 2003 .

[20]  Luiz Antonio Martinelli,et al.  Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia , 2003 .

[21]  R. Amundson,et al.  Turnover and storage of C and N in five density fractions from California annual grassland surface soils , 2002 .

[22]  R. Amundson,et al.  A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence , 2002 .

[23]  M. Fischer,et al.  Organic carbon and carbon isotopes in modern and 100‐year‐old‐soil archives of the Russian steppe , 2002 .

[24]  I. Kögel‐Knabner,et al.  Stabilization of organic matter by soil minerals — investigations of density and particle‐size fractions from two acid forest soils , 2002 .

[25]  A. Agnelli,et al.  Carbon dioxide efflux and concentrations in two soils under temperate forests , 2002, Biology and Fertility of Soils.

[26]  S. Leavitt,et al.  Dynamics of resistant soil carbon of Midwestern agricultural soils measured by naturally occurring 14C abundance , 2001 .

[27]  C. Czimczik,et al.  Comparative analysis of black carbon in soils , 2001 .

[28]  T. Hilinski.  Implementation of Exponential Depth Distribution of Organic Carbon in the CENTURY Model , 2001 .

[29]  R. B. Jackson,et al.  THE VERTICAL DISTRIBUTION OF SOIL ORGANIC CARBON AND ITS RELATION TO CLIMATE AND VEGETATION , 2000 .

[30]  Robert C. Graham,et al.  Distribution, accumulation, and fluxes of soil carbon in four monoculture lysimeters at San Dimas Experimental Forest, California , 1999 .

[31]  I. Burke,et al.  Relationship Between Root Biomass and Soil Organic Matter Pools in the Shortgrass Steppe of Eastern Colorado , 1999, Ecosystems.

[32]  R. Amundson,et al.  The impact of land use change on C turnover in soils , 1999 .

[33]  T. Kätterer,et al.  Carbon dioxide evolution from top- and subsoil as affected by moisture and constant and fluctuating temperature , 1998 .

[34]  Leif T. Jensen,et al.  A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments , 1997 .

[35]  E. Veldkamp,et al.  Soil organic carbon dynamics: variability with depth in forested and deforested soils under pasture in Costa Rica , 1997 .

[36]  P. Vitousek,et al.  Mineral control of soil organic carbon storage and turnover , 1997, Nature.

[37]  D. Jenkinson,et al.  RothC-26.3 - A Model for the turnover of carbon in soil , 1996 .

[38]  A. El-Zein,et al.  Mechanistic simulation of vertical distribution of carbon concentrations and residence times in soils , 1995 .

[39]  E. Vance,et al.  Calculating net primary production and annual input of organic matter to soil from the amount and radiocarbon content of soil organic matter , 1992 .

[40]  H. Scharpenseel,et al.  Twenty-Five Years of Radiocarbon Dating Soils: Paradigm of Erring and Learning , 1992, Radiocarbon: An International Journal of Cosmogenic Isotope Research.

[41]  Andrew P. Whitmore,et al.  method for assessing the goodness of computer simulation of soil processes , 1991 .

[42]  D. Jenkinson,et al.  Decomposition of carbon-14 labeled ryegrass and maize under tropical conditions , 1990 .

[43]  D. Jenkinson,et al.  Modelling the turnover of organic matter in long-term experiments at Rothamsted , 1987 .

[44]  H. Scharpenseel,et al.  Untersuchungen zur Kohlenstoffdynamik und Bioturbation von Mollisolen , 1986 .

[45]  K. Nakane,et al.  A MATHEMATICAL MODEL OF THE BEHAVIOR AND VERTICAL DISTRIBUTION OF ORGANIC CARBON IN FOREST SOILS , 1978 .

[46]  B. J. O'brien,et al.  Movement and turnover of soil organic matter as indicated by carbon isotope measurements , 1978 .

[47]  D. S. Jenkinson,et al.  THE TURNOVER OF SOIL ORGANIC MATTER IN SOME OF THE ROTHAMSTED CLASSICAL EXPERIMENTS , 1977 .