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\hypersetup{pdftitle={Degraded Land Rehabilitation of Coltan Mining Sites in Western Rwanda with Local Organic Materials },pdfauthor={Rodrigue V. Cao Diogo, William Nelson, Eu Sun Han, Daniel Rukazambuga, Andreas Buerkert},pdfsubject={Tropentag 2011: Abstract},pdfkeywords={Agro-forestry species, coltan mine reclamation, compost, manure shoot and root biomass, survival rate},pdfpagemode=None,colorlinks=true}
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\begin{document}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, October 5-7, 2011, Bonn}}\\[1ex] \Large{``Development on the margin''\\[2ex]}}
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\begin{center}
\Large{\textbf{Degraded Land Rehabilitation of Coltan Mining Sites in Western Rwanda with Local Organic Materials \footnote{\textbf{Contact Address:} Rodrigue V. Cao Diogo, University of Kassel, Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, Steinstraße 19, 37213~Witzenhausen, Germany, \mbox{e-mail}: \email{diogo@uni-kassel.de}}\\[0.8ex]}}
\normalsize{\textsc{Rodrigue V. Cao Diogo$^{1}$, William Nelson$^{1}$, Eu Sun Han$^{1}$, Daniel Rukazambuga$^{2}$, Andreas Buerkert$^{1}$}}
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\begin{itemize*}
\item[]{\small{\textit{$^{1}$University of Kassel, Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, Germany}}}
\item[]{\small{\textit{$^{2}$National University of Rwanda, Department of Crop Production and Horticulture, Rwanda}}}
\end{itemize*}
\index[author]{Diogo, Rodrigue V. Cao}
\index[author]{Nelson, William}
\index[author]{Han, Eu Sun}
\index[author]{Rukazambuga, Daniel}
\index[author]{Buerkert, Andreas}
\begin{center}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
Little is known about the effectiveness of low"=input methods to rehabilitate wastelands from coltan (tantalum) mining in Africa. This study therefore investigated a combination of organic soil amendments to promote the growth of leguminous agro"=forestry species on degraded soils of the Gatumba region of Western Rwanda. Three fast"=growing leguminous species, \textit{Tephrosia vogelii} Hook., \textit{Leucaena diversifolia} (Schlecht) Bentham and \textit{Cajanus cajan} (L.) Millsp. were grown over four months on three substrate types collected from the local mining sites: a pegmatite dump (S1), a technosol (S2), and a pegmatite dump developing into a gleysol (S3). These substrates were amended 1:1 (w/w) with (i)~compost (kitchen refuse plus garden waste, S1/S2/S3+CP), (ii)~manure (cattle faeces plus bedding and urine, S1/S2/S3+M) and the equal part combination of compost plus manure (S1/S2/S3+(CP+M)). Manure and compost were applied at 5 t dry matter (DM ha$^{-1}$). For all species, the growth parameters including survival rates (2 months after sowing; MAS), plant height (4 MAS), shoot dry matter (4 MAS) and root dry matter (RDM; 4 MAS) were determined. Survival rate of T vogelii was highest compared to the other species and varied from \mbox{39\,\%} (S1+M) to \mbox{56\,\%} (S1+CP+M); \mbox{50\,\%} (S2+M and S2+CP; respectively) to \mbox{61\,\%} (S2) and from \mbox{28\,\%} (S3+CP) to \mbox{67\,\%} (S3). Irrespective of soil types and species, substrate amended treatments yielded higher plants than unamended controls. \textit{C.~cajan} plants were highest averaging \mbox{54.4\,cm} for S1+CP+M, \mbox{60.2\,cm} for S2+CP+M, and \mbox{47.9\,cm} for S3+M. Although heights of \textit{T.~vogelii} were smallest regardless of substrate, its shoot dry matter (29.3 g plant$^{-1}$) and root dry matter (0.9 g plant$^{-1}$) was highest on S2 due to the combined effects of CP+M. On S3 manure application promoted the shoot development of all species, but most for \textit{T.~vogelii} (21.6 g plant$^{-1}$) corresponding to a \mbox{91\,\%} increase compared to the unamended control. Of the species tested \textit{T.~vogelii} seems most suitable for the recultivation of degraded mining soils given its high survival rate. Its development can be substantially enhanced by the application of compost or compost+manure.}

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\end{abstract}
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\noindent \textbf{Keywords:} Agro"=forestry species, coltan mine reclamation, compost, manure shoot and root biomass, survival rate
\index[key]{Coltan mine reclamation}
\index[key]{Compost}
\index[key]{Agro"=forestry species}
\index[key]{Manure shoot}
\end{document}