To cite package 'SoilR' in publications use:

Sierra, C.A., M. Mueller, S.E. Trumbore (2012). Models of soil organic matter decomposition: the SoilR package, version 1.0 Geoscientific Model Development, 5(4), 1045--1060. URL http://www.geosci-model-dev.net/5/1045/2012/gmd-5-1045-2012.html.

Corresponding BibTeX entry:

  @Article{,
    title = {Models of soil organic matter decomposition: the SoilR
      package, version 1.0},
    author = {Carlos A. Sierra and Markus Mueller and Susan E.
      Trumbore},
    journal = {Geoscientific Model Development},
    volume = {5},
    number = {4},
    pages = {1045--1060},
    year = {2012},
    url =
      {http://www.geosci-model-dev.net/5/1045/2012/gmd-5-1045-2012.html},
  }