CANFOR-01-017

Mill By-Product Study: A Study to Evaluate Mill By-products as Soil Amendments
Sponsor: 
Canadian Forest Products Ltd.
Lead Researcher: 
Brad Engel, RPF, Forestry Consultant
Body: 
This study evaluated the opportunity to utilize sawmill by-products as soil amendments.

The study was carried out on agricultural land in the Hines Creek and Grande Prairie areas of Alberta. Trials began in 1997 and were completed in March 2001. At the Grande Prairie site, nine treatments were tested: shavings, finer hog fuel, coarse hog fuel, shavings and manure, finer hog fuel and manure, coarse hog fuel and manure, composted shavings and manure, composted finer hog fuel and manure, and composted coarse hog fuel and manure. At the Hines Creek site seven treatments were tested: woodchips, sawdust, ash, wood chips and manure, sawdust and manure, composted wood chips and manure, and composted sawdust with manure. Sites were seeded to barley and underseeded to smooth bromegrass. The composted mill by-product and manure sites at the Grande Prairie trial were seeded to barley and underseeded to bromegrass and alfalfa. The forage yield for each site was then measured.

The trial resulted in a list of recommendations for the application of mill by-products to agricultural land. Wood chips, sawdust, wood ash and shavings may be applied at rates up to 8 tons per acre with no adverse effect to subsequent barley production. Finer hog fuel and coarse hog fuel may be applied at rates up to 4 tons per acre with no adverse effects to subsequent barley yields. All mill wood by-products (ie. chips, sawdust, shavings, hog fuels) when mixed with manure (approximately 50:50) and composted or not composted may be applied at rates of up to 8 tons per acre with no adverse effect to subsequent barley production. The addition of mill by-product materials to agricultural land may reduce forage yields the year after establishment (if moisture is limiting), but by the second forage year this effect will disappear regardless of treatment level. Mixing mill by-products with manure will result in higher subsequent yields of forage compared to using raw mill by-products. Additions of ash up to 8 tons per acre was also found to increase forage yields for a number of years following application.