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Oxygen Effects on Carbon, Polyphenols, and Nitrogen Mineralization Potential in Soil

2007; Wiley; Volume: 71; Issue: 1 Linguagem: Inglês

10.2136/sssaj2006.0167

1435-0661

L. M. Zibilske, J. M. Bradford,

Plant nutrient uptake and metabolism

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 O 2 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 O 2 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 O 2 concentration. The WEP ranged from 0.5 mg kg −1 soil at 0.5% O 2 to near 0 at 10 and 21% O 2 The WEC ranged from about 350 mg C kg −1 soil at 0.5% O 2 to <25 mg C kg −1 soil at 10 and 21% O 2 The ARG rates were also negatively related to O 2 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% O 2 to <0.5 mg N kg −1 soil at 21% O 2 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 O 2 availability via reduced tillage.