Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils | regenagscience

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Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils

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Title
Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils
Abstract
Increasing soil organic carbon (SOC) via organic inputs is a key strategy for increasing longterm soil C storage and improving the climate change mitigation and adaptation potential of agricultural systems. A long-term trial in California’s Mediterranean climate revealed impacts of management on SOC in maize-tomato and wheat–fallow cropping systems. SOC was measured at the initiation of the experiment and at year 19, at five depth increments down to 2 m, taking into account changes in bulk density. Across the entire 2 m profile, SOC in the wheat–fallow systems did not change with the addition of N fertilizer, winter cover crops (WCC), or irrigation alone and decreased by 5.6% with no inputs. There was some evidence of soil C gains at depth with both N fertilizer and irrigation, though high variation precluded detection of significant changes. In maize‒tomato rotations, SOC increased by 12.6% (21.8 Mg C ha-1) with both WCC and composted poultry manure inputs, across the 2m profile. The addition of WCC to a conventionally managed system increased SOC stocks by 3.5% (1.44 Mg C ha-1) in the 0 to 30 cm layer, but decreased by 10.8% (14.86 Mg C ha-1) in the 30 to 200 cm layer, resulting in overall losses of 13.4 Mg C ha-1. If we only measured soil C in the top 30 cm, we would have assumed an increase in total soil C increased with WCC alone, whereas in reality significant losses in SOC occurred when considering the 2-m soil profile. Ignoring the subsoil carbon dynamics in deeper layers of soil fails to recognize potential opportunities for soil C sequestration, and may lead to false conclusions about the impact of management practices on C sequestration.
Publication
Global Change Biology
Volume
25
Issue
11
Pages
3753-3766
Date
11/2019
Language
en
DOI
10.1111/gcb.14762
ISSN
1354-1013, 1365-2486
Accessed
2020-01-29T05:35:40Z
Library Catalog
Crossref
Citation
Tautges, N. E., Chiartas, J. L., Gaudin, A. C. M., O’Geen, A. T., Herrera, I., & Scow, K. M. (2019). Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils. Global Change Biology, 25(11), 3753–3766. https://doi.org/10.1111/gcb.14762
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