Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Long-term assessment of soil and water conservation measures (Fanya-juu terraces) on soil organic matter in South Eastern Kenya
AU - Saiz, Gustavo
AU - Wandera, Fredrick M.
AU - Pelster, David E.
AU - Ngetich, Wilson
AU - Okalebo, John R.
AU - Rufino, Mariana C.
AU - Butterbach-Bahl, Klaus
PY - 2016/7/15
Y1 - 2016/7/15
N2 - A comprehensive assessment of soil organic matter (SOM) dynamics in semi-arid agrosystems implementing soil and water conservation (SWC) measures is still lacking despite their extent, ecological and economic significance. Therefore, we assessed the long-term impact of a commonly used SWC technique (Fanya-juu terracing) on SOM-related properties in South Eastern Kenya. A soil sampling campaign was conducted in a replicated stratified random manner on three land uses that had been continuously managed for over 30 years. Samples were analyzed for organic carbon and nitrogen contents, delta C-13, delta N-15 pH and texture. Compared to sites implementing conventional agriculture, the establishment of SWC structures in this erosion-prone landscape resulted in the recovery of SOM levels comparable to those observed in neighboring semi-natural ecosystems. Sites under conventional agriculture practices contained 20 Mg C ha(-1) (0.85 m), while sites with SWC measures and those hosting semi-natural vegetation stored above a third more. There were significant differences in soil C/N ratios as well as in delta C-13 and delta N-15 values between SWC cultivation practices classified according to the presence or absence of trees. The presence of woody vegetation in sites with SWC structures had a strong impact on the spatial variability of SOM-related properties. There was also a significant negative relationship between delta N-15 values and C/N ratios across the different land uses. Our findings indicate the existence of contrasting SOM dynamics caused by vegetation-related effects, and provide suggestions for enhancing SOM storage in agricultural sites implementing SWC measures. (C) 2016 Elsevier B.V. All rights reserved.
AB - A comprehensive assessment of soil organic matter (SOM) dynamics in semi-arid agrosystems implementing soil and water conservation (SWC) measures is still lacking despite their extent, ecological and economic significance. Therefore, we assessed the long-term impact of a commonly used SWC technique (Fanya-juu terracing) on SOM-related properties in South Eastern Kenya. A soil sampling campaign was conducted in a replicated stratified random manner on three land uses that had been continuously managed for over 30 years. Samples were analyzed for organic carbon and nitrogen contents, delta C-13, delta N-15 pH and texture. Compared to sites implementing conventional agriculture, the establishment of SWC structures in this erosion-prone landscape resulted in the recovery of SOM levels comparable to those observed in neighboring semi-natural ecosystems. Sites under conventional agriculture practices contained 20 Mg C ha(-1) (0.85 m), while sites with SWC measures and those hosting semi-natural vegetation stored above a third more. There were significant differences in soil C/N ratios as well as in delta C-13 and delta N-15 values between SWC cultivation practices classified according to the presence or absence of trees. The presence of woody vegetation in sites with SWC structures had a strong impact on the spatial variability of SOM-related properties. There was also a significant negative relationship between delta N-15 values and C/N ratios across the different land uses. Our findings indicate the existence of contrasting SOM dynamics caused by vegetation-related effects, and provide suggestions for enhancing SOM storage in agricultural sites implementing SWC measures. (C) 2016 Elsevier B.V. All rights reserved.
KW - Semi-arid ecosystems
KW - Soil water conservation
KW - Climate-smart agriculture
KW - Small household farms
KW - Soil organic carbon
KW - Stable isotopes
KW - TREE-GRASS INTERACTIONS
KW - CARBON STOCKS
KW - WEST-AFRICA
KW - PRECIPITATION GRADIENT
KW - SPATIAL VARIABILITY
KW - ECOSYSTEM SERVICES
KW - N2O EMISSIONS
KW - BULK-DENSITY
KW - NITROGEN
KW - PLANT
U2 - 10.1016/j.geoderma.2016.03.022
DO - 10.1016/j.geoderma.2016.03.022
M3 - Journal article
VL - 274
SP - 1
EP - 9
JO - Geoderma
JF - Geoderma
SN - 0016-7061
ER -