Acknowledgements
We would like to thank Agency of Agricultural Research and Development,
Ministry of Agriculture, Indonesia, for financial and technical support.
We thank Mr. Martinus Halim, Mr. M. Abu, Mr. Yace Hidayat and Ms Lenita
(Centre for Agricultural Land Resource Research and Development) for
their field soil sampling and laboratory assistance. The data used to
produce the results in this paper can be obtained from the first author
by request.