Paper Mill Sludge as a Replacement for the Cellulosic Component of Hydroseed Mixtures

Abstract

Pulp and paper mill sludge is composed of cellulosic waste and clay, and rich in microorganisms that can benefit horticulture. However, its application in horticulture has received less research attention.Field and greenhouse studies were carried out to determine if sludge from a case study industry can replace the typical cellulosic additive utilized in hydroseeding, and the ideal application rate of a sludge-soil-seed mixture. The treatments were 0 - 100% sludge and soil by mass with a consistent mass of embedded seeds of Kentucky Bluegrass (Poa pratensis), Creeping Red Fescue (Festuca rubra), Perennial (Lolium perenne) and Annual Ryegrass (Lolium multiflorum). Seeding with a top layer of soil and 5 to 75% sludge gave the best outcome using a cellulosic additive after 3 weeks of growth. Mixtures containing 5- 25% sludge resulted in the quickest seed germination rate. The cellulosic additive has the capacity to retain a higher volume of water but requires 15 times more material by volume. An increase in sludge increased water retention by 20%. Overall, the cellulosic additive in hydroseeding applications can be replaced by sludge without plant detriment. However, further testing is needed to determine long-term effects.