Item Details

Title: Soil Carbon, Nitrogen and Phosphorus Contents along a Gradient of Agricultural Intensity in the Kilombero Valley, Tanzania

Date Published: 2020
Author/s: John Livsey, Edmond Alavaisha, Madaka Tumbo, Steve W. Lyon, Antonio Canale, Michele Cecotti, Regina Lindborg and Stefano Manzoni
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Funding Agency :
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Affiliation: Department of Physical Geography, Stockholm University, 106 91 Stockholm, Sweden; (E.A.); (S.W.L.); (R.L.); (S.M.)
2 Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
Institute of Resource Assessment, University of Dar es Salaam, Dar es Salaam 35097, Tanzania;
4 School of Environment and Natural Resources, Ohio State University, Columbus, OH 43210, USA
5 Department of Statistical Sciences, University of Padova, 35121 Padua, Italy; (A.C.); (M.C.), MDPI
Keywords: soil organic carbon; agricultural intensity; nitrogen; phosphorous; irrigation; fertilization


The preservation of soils which provide many important services to society is a pressing
global issue. This is particularly the case in countries like Tanzania, which will experience rapid
population growth over coming decades. The country is also currently experiencing rapid land-use
change and increasing intensification of its agricultural systems to ensure sufficient food production.
However, little is known regarding what the long term effects of this land use change will be, especially
concerning soil quality. Therefore, we assessed the effect of irrigation and fertilization in agricultural
systems, going from low intensity smallholder to high intensity commercial production, on soil
organic carbon (SOC), total nitrogen (TN), and total phosphorous (TP) concentrations and stocks. Soil
sampling was conducted within Kilombero Plantations Ltd. (KPL), a high intensity commercial farm
located in Kilombero, Tanzania, and also on surrounding smallholder farms, capturing a gradient
of agricultural intensity. We found that irrigation had a positive effect on SOC concentrations and
stocks while fertilization had a negative effect. Rain-fed non-fertilized production had no effect on
soil properties when compared to native vegetation. No difference was found in concentrations of
TN or TP across the intensity gradient. However, TN stocks were significantly larger in the surface
soils (0–30 cm) of the most intensive production system when compared to native vegetation and
smallholder production