\documentclass[english,german]{scrartcl}
\usepackage[latin1]{inputenc}
\usepackage{geometry}
\geometry{verbose,a4paper,tmargin=1.75cm,bmargin=2cm,lmargin=2cm,rmargin=2cm,headheight=0.8cm,headsep=0.5cm,footskip=0.5cm}
\usepackage{babel}
\usepackage{url}
\urlstyle{same}
\newcommand\email{\begingroup \urlstyle{same}\Url}\usepackage{graphicx}
\usepackage{units}
\usepackage{tabularx}
\usepackage{wasysym} % enable use of \permil instead of \textperthousand
\usepackage{marvosym}
\usepackage{arabtex}
\usepackage{hyphenat}
\usepackage{booktabs}
\usepackage{mdwlist}
\renewcommand{\thefootnote}{\relax}
\usepackage{index}
\newindex{key}{kdx}{knd}{Keywords}
\newindex{author}{idx}{ind}{Authors}
\usepackage{fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrulewidth}{0pt}
\fancyfoot{}
\usepackage{ifpdf}
\ifpdf
%\usepackage[activate]{pdfcprot}
%\usepackage[owner=Tapioka, print=true, copy=true, edit=false, annotate=false,set]{pdfcrypt}
%encryption: not supported any more (since pdftex 1.10)
\usepackage[pdftex]{thumbpdf}
\usepackage[pdftex]{hyperref}
\hypersetup{pdftitle={Fate of Particulate and Dissolved Organic Matter in Soil N Mineralisation},pdfauthor={Bandhu Raj Baral, Gautam Shrestha},pdfsubject={Tropentag 2011: Abstract},pdfkeywords={15N enrichment , bioavailable fraction, dissolved organic carbon, dissolved organic matter, dissolved organic nitrogen, particulate organic matter},pdfpagemode=None,colorlinks=true}
\else
\usepackage{ae}
\usepackage{textcomp}
\fi
\begin{document}
\ifpdf
\parbox[b]{2.5cm}{\resizebox*{2.5cm}{!}{\includegraphics{dtt2011.jpg}}}
\else
\parbox[b]{2.5cm}{\resizebox*{2.5cm}{!}{\includegraphics{dtt2011.eps}}}
\fi
\hfill
\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, October 5-7, 2011, Bonn}}\\[1ex] \Large{``Development on the margin''\\[2ex]}}
\hspace{0.1cm}
\begin{center}
\Large{\textbf{Fate of Particulate and Dissolved Organic Matter in Soil N Mineralisation\footnote{\textbf{Contact Address:} Bandhu Raj Baral, Wageningen University and Research Centre, Soil Quality, Bornsesteeg 1, Wageningen, 6708GA,~Wageningen, The Netherlands, \mbox{e-mail}: \email{bandhu_baral@yahoo.com}}\\[0.8ex]}}
\normalsize{\textsc{Bandhu Raj Baral, Gautam Shrestha}}
\end{center}
\begin{itemize*}
\item[]{\small{\textit{Wageningen University and Research Centre, Soil Science, The Netherlands}}}
\end{itemize*}
\index[author]{Baral, Bandhu Raj}
\index[author]{Shrestha, Gautam}
\begin{center}
\vspace{1.1cm}
\textbf{Abstract}
\begin{abstract}
\normalsize{
The transformation of insoluble organic N via particulate and dissolved organic matter (POM and DOM) into inorganic N may represent the bottle neck mechanism in N mineralisation. However, it is unknown how POM fractions are related to DOM pools, and how these particulate and dissolved pools are quantitatively involved in N mineralisation. To understand and quantify the fate of these pools in N mineralisation, we conducted an incubation experiment with $^{15}$N labeled radish residues to trace the flow of $^{15}$N through the different N pools. POM was fractionated with density fractionation as light and heavy fraction (LF and HF). The dissolved organic matter fraction was collected using a centrifugal drainage technique and subsequently separated into a bioavailable and recalcitrant fraction. The enrichment of $^{15}$N in POM, DON and inorganic N along with their concentrations were examined to identify their role in N mineralisation. Our analysis showed that neither DON nor POM function as a distinct N source fraction in soil. The collected DOM was predominantly recalcitrant (80\,\%), suggesting that the bioavailable DOM fraction cannot be measured with current sampling techniques. The concentration of DOM strongly increases upon incorporation of crop residues, but diminish sharply within a few days. Our results also suggest that the DOM fraction is heterogeneous in composition; the most bioavailable part is consumed within a few days whereas the remaining part is fairly constant. Moreover, the mineralisation rate of crop residue increased with incubation time but the $^{15}$N enrichment of DON showed gradual decrease in time. The gradual decrease of $^{15}$N enrichment in DON indicates that there was no change in their inputs. Hence these results suggested that a change in the turnover rate of DON was not associated with the N mineralisation rate of crop residue. From these results,we concluded  that the main flow of decomposed N from residue did not pass or may not necessary to pass via the DON pool. Further research should focus on bioavailable fraction analysis.}

\vspace{0.5cm}
\end{abstract}
\end{center}
\noindent \textbf{Keywords:} $^{15}$N enrichment, bioavailable fraction, dissolved organic carbon, dissolved organic matter, dissolved organic nitrogen, particulate organic matter
\index[key]{Nitrogen!$^{15}$N enrichment}
\index[key]{Bioavailable fraction}
\index[key]{Organic!carbon!dissolved}
\index[key]{Organic!matter!dissolved}
\index[key]{Organic nitrogen!dissolved}
\index[key]{Organic!matter}
\index[key]{Soil!mineralisation}
\end{document}