Experimental Project (EP) 886.13 Maximizing the Productivity of Lodgepole Pine and Spruce in the Interior of British Columbia was implemented by the B.C. Ministry of Forests Research Branch in 1992 to examine the potential to dramatically improve the productivity of interior forests by permanently alleviating nutritional growth constraints. Nine area-based field installations (six pine and three spruce) were established on representative sites within three biogeoclimatic zones between 1992 and 1999. The growth and yield objectives of the "maximum productivity" study are to compare the effects of different regimes and frequencies of repeated fertilization on forest growth and development and to determine optimum fertilization regimes for maximizing stand volume production. In addition, several companion studies have been undertaken at selected sites to determine the long-term effects of large nutrient additions on above- and belowground timber and non-timber forest resources. The purpose of this report is to examine the 12-year effects of repeated fertilization on forest floor and mineral soil properties at two study sites (one pine and one spruce) in central British Columbia.--Document.