@article{725fea7915d04d748415ff138239723b,
title = "Influence of ammonium on fine root development and rhizosphere pH of Douglas-fir seedlings in sand.",
keywords = "ammonium, nitrogen, Pseudotsuga menziesii, rhizosphere pH, sand culture, shoot/root ratio, specific root length (SRL), toxicity",
author = "A.F.M. Olsthoorn and W.G. Keltjens and \{van Baren\}, B. and M.C.G. Hopman",
year = "1991",
doi = "10.1007/bf00011901",
language = "English",
volume = "133",
pages = "75--81",
journal = "Plant and Soil",
issn = "0032-079X",
publisher = "Springer",
}