New Zealand Soil Classification (NZSC)
The top three levels of the NZSC classification - order, group, and subgroup - are defined by Hewitt (2010), the fourth and fifth levels (family and sibling) by Webb and Lilburne (2011). The fourth level (soilforms) by Clayden and Webb (1994) were replaced by the family and sibling.
The current approach to drainage classes is highlighted here.
The resulting classification represents the best attempt to classify New Zealand soils, at our current state of knowledge. As knowledge and understanding of soils grows, further revisions will be necessary.