Browsing by Author "Munera-Echeverri, Jose L."

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    Biochar Application to Soil for Increased Resilience of Agroecosystems to Climate Change in Eastern and Southern Africa
    (Springer, Cham, 2019) Obia, Alfred; Martinsen, Vegard; Cornelissen, Gerard; Børresen, Trond; Botnen Smebye, Andreas; Munera-Echeverri, Jose L.; Mulder, Jan
    With the current unreliable rainfall pattern, which is expected to worsen due to climate change, agricultural production might become more challenging especially among resource-poor farmers in Eastern and Southern Africa. This calls for adaptation of farming systems to overcome this emerging challenge. Biochar, a product of biomass pyrolysis, with long-term evidence from Amazonia, might contribute to a climate-resilient farming system. This is due to its positive effects on soil chemical and physical properties resulting in increased crop yields, which has been experimentally demonstrated largely within the last two decades. In acidic low cation exchange capacity (CEC) soils, biochar derived from corncob at 5% application rate, for example, increased pH by ≥1 unit and CEC by ≥2 cmolc kg−1 in addition to direct nutrient supply. Increased CEC may be linked to the observed increase in soil organic carbon content (biochar carbon/sequestered carbon) due to biochar addition. Sequestration of carbon due to biochar has been reported to be stronger in soils that have low pH and low carbon contents, with greater effects from biochars
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    Significant build-up of soil organic carbon under climate-smart conservation farming in Sub-Saharan Acrisols
    (Science of The Total Environment, 2019) Martinsen, Vegard; Munera-Echeverri, Jose L.; Obia, Alfred; Cornelissen, Gerard; Mulder, Jan
    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