NURSERY BARK MIXTUREThe University of Illinois has developed a potting mixture for nursery crops such as trees, shrubs and woody groundcovers.
Commercial Hardwood Bark, small enough to pass through a 1/2 inch mesh screen. Six (6) pounds of ammonium nitrate Two and one-half (2 1/2) pounds triple super phosphate Two (2) pounds sulfur Two (2) pounds iron sulfate One (1) pound epsom salts
Combine and wet ingredients to 70 percent moisture.
Compost 30 days and turn; compost another 30 days and turn; compost 30 more days (90 days total) and use. Maintain a 70 percent moisture rate throughout composting.
Mixture can be combined with rice hulls at rate of 70 parts bark to 30 parts rice hulls.
If using pine bark, omit nitrogen, sulfur, iron sulfate and epsom salts. Add 5 pounds dolomitic limestone.
Mixture of 50 percent pine bark potting medium and 50 percent hardwood bark medium works well.