Richard Mulvaney - Amino Sugars, Illinois Soil N Test
Clay Aging, esp. due to Anhydrous
Modes of K: Use sulfate, not muriated
Chloride competes with nitrate
Cropsmith; Ken Ferrie's Variable N
A Living Soil Handbook - Jesse Frost
Hay in a Day
Joel Williams Foliar N course - integratedsoils.com
AEA Soil Primer
16 groups / families of plants??