Lime for Michigan Soils
D.R. Christenson and D. Warncke
MSU Extension Bullettin E-471, Reprinted 1998
Soil pH Management for Christmas Tree Production
North Carolina State University Extension
Soil pH Measurement with a Portable Meter
Joseph R. Heckman
Soils and Christmas Tree Production Part 4: Soil pH
M. R. Koelling
Soil for Plant Growth
Tillage Systems for Michigan Soils and Crops
L.S. Robertson et al. 1977
MSU Extension Bulletin E-1042, January 1977.
Understanding Soil II: Soil Chemistry
David Rothstein 2006
Soils and Christmas Tree Production: Part 3: Soil Moisture.
Randy Heiligmann