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This article in SSSAJ

  1. Vol. 65 No. 2, p. 431-441
     
    Received: Jan 3, 2000


    * Corresponding author(s): cesar.izaurralde@pnl.gov
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doi:10.2136/sssaj2001.652431x

Carbon Balance of the Breton Classical Plots over Half a Century

  1. R.C. Izaurralde *a,
  2. W.B. McGillb,
  3. J.A. Robertsonb,
  4. N.G. Jumab and
  5. J.J. Thurstonb
  1. a Pacific Northwest National Laboratories, 901 D Street S.W., Ste. 900, Washington, DC 20024-2115
    b Dep. of Renewable Resources, University of Alberta, 4-42 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada

Abstract

We related C input and management to soil organic C (SOC) dynamics over 51 yr (1939–1990). We used two rotations from the Breton Classical Plots at Breton, Canada, on a Typic Cryoboralf: (i) wheat (Triticum aestivum L.)–fallow (WF) and (ii) wheat–oat (Avena sativa L.)–barley (Hordeum vulgare L.)–hay (primarily alfalfa, Medicago sativa L.)–hay (WOBHH), in factorial combination with three fertility levels: no added fertilizer [Nil], N-P-K-S fertilizers [F], and farmyard manure [M]. Net aboveground C productivity (NAGCP, kg ha−1 yr−1) averaged 576 in WF–Nil and 1078 in WF–F and SOC decreased in both, but NAGCP averaged 1208 in WF–M, where SOC increased. A NAGCP of 853 in WOBHH–Nil maintained SOC, while both 1831 in WOBHH–F and 1714 in WOBHH–M increased SOC. After 51 yr, WOBHH–M had 25 Mg ha−1 more SOC than did WF–Nil. Because of contrasting decay rates and root/shoot ratios, C input needed to maintain the original SOC was twofold greater in WF than in WOBHH, which required a fourfold increase in NAGCP to attain these inputs. A three-compartment model fitted to the data suggested loss of C from the active compartments and gain of C by the passive compartments. Inputs of C that maintained SOC over 51 yr would lead to a steady state of 2.9 times more C than in 1939, and 26% higher than the native SOC content. Return of 30% of the crop C as manure would sustain SOC sequestration in all WOBHH rotations with NAGCP > 400 kg ha−1 yr−1 and in those WF rotations with NAGCP > 1000 kg ha−1 yr−1

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Copyright © 2001. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.65:431–441.