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This article in JEQ

  1. Vol. 39 No. 3, p. 784-790
     
    Received: Aug 20, 2009
    Published: May, 2010


    * Corresponding author(s): david.clay@sdstate.edu
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doi:10.2134/jeq2009.0321

Biomass Estimation Approach Impacts on Calculated Soil Organic Carbon Maintenance Requirements and Associated Mineralization Rate Constants

  1. David Clay *,
  2. Gregg Carlson,
  3. Thomas Schumacher,
  4. Vance Owens and
  5. Francisco Mamani-Pati
  1. Plant Science Dep., South Dakota State Univ., Brookings, SD 57007. Assigned to Associate Editor Tsutomu Ohno

Abstract

To reduce atmospheric CO2 concentrations and provide food for a growing world population, sustainable management practices must be adopted. An important consideration in the development of sustainable practices is the maintenance of soil organic carbon (SOC). Critical assumptions, with unknown errors, are used to calculate SOC maintenance requirements. This study investigated the impact of three approaches for estimating belowground nonharvested carbon (NHC) on SOC maintenance requirements, SOC and nonharvested C mineralization rate constants, and the capacity of the soil to sequester carbon. Common protocols were used to develop databases from eight historical carbon studies. The SOC to CO2 (k SOC) and NHC to SOC (k NHC) rate constants were calculated using the model NHCa/SOCi = k SOC/k NHC + dSOC/dt(1/k NHCSOCi), where NHCa is the amount of applied NHC, SOCe is SOC at the equilibrium point, t = time, and SOCi is the initial SOC value. Analysis showed that (i) despite the difficulty in measuring belowground biomass, it is needed to calculate the SOC and NHC mineralization rate constants when using nonisotopic approaches; (ii) decreasing NHC by reducing the relative contribution of roots to NHC reduced the calculated SOC maintenance requirements and the amount of corn stover that could be sustainably harvested; iii) changes in the belowground NHC calculation approach do not result in a consistent impact on calculated rate constants; iv) changes in the belowground NHC calculation approach had a minimal impact on the calculated carbon sequestration potential (k NHCNHC)/k SOC; (v) SOC at the beginning of the experiments was negatively correlated with temperature, while k SOC was positively correlated with tillage intensity; and (vi) the k SOC and k NHC rate constants can be used to directly assess the impact of different management scenarios on carbon turnover.

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Copyright © 2010. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyAmerican Society of Agronomy, Crop Science Society of America, and Soil Science Society of America