Significant build-up of soil organic carbon under climate-smart conservation farming in Sub-Saharan Acrisols
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Date
2019
Journal Title
Journal ISSN
Volume Title
Publisher
Science of The Total Environment
Abstract
Conservation farming (CF) involving minimum tillage, mulching and crop rotation may offer climate change adaptation
and mitigation benefits. However, reported effects of CF, as applied by smallholders, on storage of soil
organic carbon (SOC) and soil fertility in Sub-Saharan Africa differ considerably between studies. This is partly
due to differences in management practice, soil type and adoption level between individual farmers. Where CF
involves planting basins, year-to-year changes in position of basins make SOC stock estimates more uncertain.
Here we assess the difference in SOC build-up and soil quality between inside planting basins (receiving inputs
of lime and fertilizer; basins opened each year) and outside planting basins (no soil disturbance or inputs
other than residues) under hand-hoe tilled CF in an Acrisol at Mkushi, Zambia. Seven years of strict CF husbandry
significantly improved soil quality inside planting basins as compared with outside basins. Significant effects
were found for SOC concentration (0.74 ± 0.06% vs. 0.57 ± 0.08%), SOC stock (20.1 ± 2.0 vs. 16.4 ±
2.6 t ha−1, 0–20 cm), soil pH (6.3 ± 0.2 vs. 4.95± 0.4) and cation exchange capacity (3.8 ± 0.7 vs. 1.6 ±
0.4 cmolc kg−1). As planting basins only occupy 9.3% of the field, the absolute rate of increase in SOC, compared
with outside basins, was 0.05 t C ha−1 yr−1 This corresponds to an overall relative increase of 2.95‰SOC yr−1 in
the upper 20 cm of the soil. Also, hot water extractable carbon (HWEC), a proxy for labile organic matter, and
Description
Keywords
Hand-hoe tillage, Planting, basin, Soil fertility, Soil sampling
Citation
Martinsen, V., Munera-Echeverri, J. L., Obia, A., Cornelissen, G., & Mulder, J. (2019). Significant build-up of soil organic carbon under climate-smart conservation farming in Sub-Saharan Acrisols. Science of The Total Environment, 660, 97-104.