Contrasting agricultural management effects on soil organic carbon dynamics between topsoil and subsoil

Author(s)
Osanai, Yui
Knox, Oliver
Nachimuthu, Gunasekhar
Wilson, Brian
Publication Date
2020-08-21
Abstract
Agricultural practices (e.g. tillage, crop rotation and fertiliser application) have a strong influence on the balance between carbon (C) input and output by altering physicochemical and microbial properties that control decomposition processes in the soil. Recent studies suggest that the mechanisms by which agricultural practice impacts soil organic carbon (SOC) dynamics in the topsoil may not be the same as those in the subsoil. Here, we assessed SOC stock, soil organic fractions and nitrogen availability to 1.0 m in soils under a cotton (<I>Gossypium hirsutum L</I>.)-based cropping system, and assessed the impact of agricultural management (three historical cropping systems with or without maize (<I>Zea mays L</I>.) rotation) on SOC storage. We found that the maize rotation and changes in the particulate organic fraction influenced SOC stock in the topsoil, although the overall change in SOC stock was small. The large increase in subsoil SOC stock (by 31%) was dominated by changes in the mineral-associated organic fraction, which were influenced by historical cropping systems and recent maize rotation directly and indirectly via changes in soil nitrogen availability. The strong direct effect of maize rotation on SOC stock, particularly in the subsoil, suggests that the direct transfer of C into the subsoil SOC pool may dominate C dynamics in this cropping system. Therefore, agricultural management that affects the movement of C within the soil profile (e.g. changes in soil physical properties) could have a significant consequence for subsoil C storage.
Citation
Soil Research, 59(1), p. 24-33
ISSN
1838-6768
1838-675X
Link
Publisher
CSIRO Publishing
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
Title
Contrasting agricultural management effects on soil organic carbon dynamics between topsoil and subsoil
Type of document
Journal Article
Entity Type
Publication

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