TECHNICAL BULLETIN

Value-added utilization of composted manures
Dr. Harry Hoitink
Ohio State University

Plant loss due to soil-borne plant diseases such Phytophthera root rot has decreased from 75% to 1 % in the container industry with the incorporation of biodegradable organic matter into the planting media. Composted biosolids provide disease-suppressive microorganisms and aged pine bark provides the lignin and lignin- protected cellulose that creates an environment in which the organisms can thrive. Composted biosolids have also been used successfully in the nursery industry. To effectively suppress disease, com post must reach temperatures that will kill pathogens and have the appropriate chemical (nutrients) and physical factors (drainage, aeration and available water).

Opportunities exist in the container and nursery industries to use livestock manure as a source of biodegradable organic matter. Wood mulches, which are associated with nitrogen immobilization and fungi, can also benefit from the addition of manure. Analyses of composted swine manure have similar chemical and physical properties and pilot studies indicate that plant response may improve with additions of 4% to 8% to the planting media. However, high salts from urine and liquid manure systems present challenges for utilizing livestock manure. Additional research is needed to reduce salt levels in composted manure and to develop "dry" manure management systems or methods for com posting high liquid manure.