Landscape-scale variability of soil health indicators: effects of cultivation on soil organic carbon in the Usambara Mountains of Tanzania
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Date
2015-11-02
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Land-use change continues at an alarming
rate in sub-Saharan Africa adversely affecting ecosystem
services provided by soil. These impacts are
greatly understudied, especially in biodiversity rich
mountains in East Africa. The objectives of this study
were to: conduct a biophysical baseline of soil and
land health; assess the effects of cultivation on soil
organic carbon (SOC); and develop a map of SOC at
high resolution to enable farm-scale targeting of
management interventions. Biophysical field surveys
were conducted in a 100 km2 landscape near Lushoto,
Tanzania, with composite soil samples collected from
160 sampling plots. Soil erosion prevalence was
scored, trees were counted, and current and historic
land use was recorded at each plot. The results of the
study showed a decline in SOC as a result of
cultivation, with cultivated plots (n = 105) having mean topsoil OC of 30.6 g kg-1, while semi-natural
plots (n = 55) had 71 g OC kg-1 in topsoil. Cultivated
areas were also less variable in SOC than seminatural
systems. Prediction models were developed for
the mapping of SOC based on RapidEye remote
sensing data for January 2014, with good model
performance (RMSEPcal = 8.0 g kg-1; RMSEPval =
10.5 g kg-1) and a SOC map was generated for the
study. Interventions will need to focus on practices
that increase SOC in order to enhance productivity and
resilience of the farming system, in general. The highresolution
maps can be used to spatially target
interventions as well as for monitoring of changes in
SOC.
Description
This article is published with open access at Springerlink.com
Keywords
Land-use change, Land health, Cropping diversity, Usambara Mountains