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This article in SSSAJ

  1. Vol. 71 No. 1, p. 133-139
    Received: Apr 24, 2006

    * Corresponding author(s): lzibilske@weslaco.ars.usda.gov
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Oxygen Effects on Carbon, Polyphenols, and Nitrogen Mineralization Potential in Soil

  1. L. M. Zibilske * and
  2. J. M. Bradford
  1. USDA-ARS Integrated Farming and Natural Resour. Res. Unit, 2413 E. Hwy. 83, Weslaco, TX 78596-8344


Crop residue decomposition is affected by environmental factors and residue biochemical properties. These factors may contribute to management protocols that enhance soil organic matter accumulation in hot climates, which have characteristically high oxidation rates. The purpose of this experiment was to determine O2 effects on soil polyphenol oxidase (PPO), peroxidase (PO), water-soluble polyphenolics (WEP), arginine ammonification (ARG), and water-extractable C (WEC). Cowpea (Vigna unguiculata L.) and sorghum [Sorghum bicolor (L.) Moench] residues in soil were incubated with headspace O2 concentrations of 0.5, 10, or 21% (ambient) for up to 110 d. The PPO and PO were negatively related to WEP and WEC, mostly at 10 and 21% (P < 0.05). The WEP and WEC were significantly (P < 0.05) and negatively related to O2 concentration. The WEP ranged from 0.5 mg kg−1 soil at 0.5% O2 to near 0 at 10 and 21% O2 The WEC ranged from about 350 mg C kg−1 soil at 0.5% O2 to <25 mg C kg−1 soil at 10 and 21% O2 The ARG rates were also negatively related to O2 level with cowpea, but not as strongly as with sorghum. The ARG and WEC were negatively correlated. The ARG ranged from 6 mg N kg−1 soil at 0.5% O2 to <0.5 mg N kg−1 soil at 21% O2 through 110 d. The WEC and WEP varied independently during incubation. Our results suggest that soil organic C accumulation may be stimulated by (i) using cover crops with higher polyphenolic content, which could slow C mineralization, and (ii) restricting soil O2 availability via reduced tillage.

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