Update journal-of-plant-nutrition-and-soil-science.csl

Updated in-text citation according to current JPNSS author guidelines, see: http://onlinelibrary.wiley.com/store/10.1002/(ISSN)1522-2624/asset/homepages/Instructions_for_Authors_2014Sept.pdf
Update journal-of-plant-nutrition-and-soil-science.csl

Right .. one obsolete line omitted.
Merge pull request #1293 from zsteinmetz/patch-1

Update journal-of-plant-nutrition-and-soil-science.csl