The contribution of crop residues to changes in soil pH under field conditions

Butterly, C. R. and Baldock, J. A. and Tang, C. (2012) The contribution of crop residues to changes in soil pH under field conditions. Plant Soil. pp. 1-14.

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Background and Aims Crop residues are important for the redistribution of alkalinity within soils. A net increase in pH following residue addition to soil is typically reported. However, effects are inconsistent in the field due to confounding soil processes and agronomic practises. Methods A column experiment investigated the effects of canola, chickpea and wheat residues, differing in alkalinity content and C:N ratio, on soil pH changes in a Podosol (Podzol; initial pH 4.5) and Tenosol (Cambisol; initial pH 6.2) under field conditions. Results Residues (10 g dry matter kg-1 soil; 0–10 cm) increased soil pH, and temporal changes in alkalinity depended on the residue and soil type. Alkalinity was generated via abiotic association reactions between H+ and added organic matter and via ammonification and decarboxylation processes during decomposition. Alkalinity from canola and chickpea residues moved down the soil profile (10–30 cm) and was attributed to nitrate immobilisation and organic anion decomposition by soil microbes.Conclusions The application of residues to acid and moderately acid soils increased the pH of both topsoil and subsoils, which persisted over 26 months. Maximal increase of pH observed at 3 months was correlated with the concentration of excess cations in the residues.

Item Type: Article
Additional Information: This research was supported by an Australian Research Council Discovery Project fund (DP0877882).
Uncontrolled Keywords: Decomposition, Initial pH, Long-term, Nitrogen cycle, Soluble alkalinity, Soil acidification, Soil type.
Author Affiliation: Department of Agricultural Sciences, LaTrobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia
Subjects: Soil Science and Microbiology > Soil Sciences
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 06 Sep 2012 03:44
Last Modified: 06 Sep 2012 03:46
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