TY - JOUR

T1 - Greenhouse gas fluxes from agricultural soils of Kenya and Tanzania

AU - Rosenstock, Todd S.

AU - Mpanda, Mathew

AU - Pelster, David E.

AU - Butterbach-Bahl, Klaus

AU - Rufino, Mariana C.

AU - Thiong'o, Margaret

AU - Mutuo, Paul

AU - Abwanda, Sheila

AU - Rioux, Janie

AU - Kimaro, Anthony A.

AU - Neufeldt, Henry

N1 - ©2016. American Geophysical Union. All Rights Reserved.

PY - 2016/6

Y1 - 2016/6

N2 - Knowledge of greenhouse gas (GHG) fluxes in soils is a prerequisite to constrain national, continental, and global GHG budgets. However, data characterizing fluxes from agricultural soils of Africa are markedly limited. We measured carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes at 10 farmer-managed sites of six crop types for 1 year in Kenya and Tanzania using static chambers and gas chromatography. Cumulative emissions ranged between 3.5–15.9 Mg CO2-C ha−1 yr−1, 0.4–3.9 kg N2O-N ha−1 yr−1, and −1.2–10.1 kg CH4-C ha−1 yr−1, depending on crop type, environmental conditions, and management. Manure inputs increased CO2 (p = 0.03), but not N2O or CH4, emissions. Soil cultivation had no discernable effect on emissions of any of the three gases. Fluxes of CO2 and N2O were 54–208% greater (p < 0.05) during the wet versus the dry seasons for some, but not all, crop types. The heterogeneity and seasonality of fluxes suggest that the available data describing soil fluxes in Africa, based on measurements of limited duration of only a few crop types and agroecological zones, are inadequate to use as a basis for estimating the impact of agricultural soils on GHG budgets. A targeted effort to understand the magnitude and mechanisms underlying African agricultural soil fluxes is necessary to accurately estimate the influence of this source on the global climate system and for determining mitigation strategies.

AB - Knowledge of greenhouse gas (GHG) fluxes in soils is a prerequisite to constrain national, continental, and global GHG budgets. However, data characterizing fluxes from agricultural soils of Africa are markedly limited. We measured carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes at 10 farmer-managed sites of six crop types for 1 year in Kenya and Tanzania using static chambers and gas chromatography. Cumulative emissions ranged between 3.5–15.9 Mg CO2-C ha−1 yr−1, 0.4–3.9 kg N2O-N ha−1 yr−1, and −1.2–10.1 kg CH4-C ha−1 yr−1, depending on crop type, environmental conditions, and management. Manure inputs increased CO2 (p = 0.03), but not N2O or CH4, emissions. Soil cultivation had no discernable effect on emissions of any of the three gases. Fluxes of CO2 and N2O were 54–208% greater (p < 0.05) during the wet versus the dry seasons for some, but not all, crop types. The heterogeneity and seasonality of fluxes suggest that the available data describing soil fluxes in Africa, based on measurements of limited duration of only a few crop types and agroecological zones, are inadequate to use as a basis for estimating the impact of agricultural soils on GHG budgets. A targeted effort to understand the magnitude and mechanisms underlying African agricultural soil fluxes is necessary to accurately estimate the influence of this source on the global climate system and for determining mitigation strategies.

KW - mitigation

KW - soil fluxes

KW - nitrous oxide

KW - carbon dioxide

KW - climate change

KW - Africa

KW - NITROUS-OXIDE EMISSIONS

KW - SUB-SAHARAN AFRICA

KW - N2O EMISSIONS

KW - ATMOSPHERE EXCHANGE

KW - EASTERN AMAZONIA

KW - LAND-USE

KW - FERTILIZER NITROGEN

KW - IMPROVED FALLOW

KW - NO

KW - CO2

U2 - 10.1002/2016JG003341

DO - 10.1002/2016JG003341

M3 - Journal article

VL - 121

SP - 1568

EP - 1580

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 2169-8953

IS - 6

ER -