Utah State University Extension
The Utah Fertilizer Guide is designed to provide practical answers to routine questions related to soil fertility management. The guide emphasizes laboratory analysis of soil and plant samples as the keystone to optimum fertilizer rates for maximum economic plant yield and quality. The focus of the guide is on soil fertility problems peculiar to the semi-arid and arid soils of Utah.
James, D. W. and Topper, K. F., "Utah Fertilizer Guide" (2010). All Current Publications. Paper 832.