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ARS Home » Northeast Area » Orono, Maine » New England Plant, Soil and Water Research Laboratory » Research » Publications at this Location » Publication #189029
Title: COMPOST MATURITY EFFECTS ON NITROGEN AND CARBON MINERALIZATION AND PLANT GROWTH

Author
item Griffin, Timothy
item HUTCHINSON, MARK - UNIV OF MAINE

Submitted to: Compost Science and Utilization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2007
Publication Date: 12/10/2007
Citation: Griffin, T.S., Hutchinson, M. 2007. Compost maturity effects on nitrogen and carbon mineralization and plant growth. Compost Science and Utilization. 15(4):228-236.

Interpretive Summary: Improved predictive relationships between compost maturity and nitrogen (N) availability would be helpful in managing these soil amendments as nutrient inputs. We collected 13 compost samples from a single windrow over a 91 d period, beginning when the compost met minimal National Organic Program standards. Compost maturity and stability were assessed using both standard chemical analyses (total C and N, mineral N, total volatile solids) and other methods (CO2 evolution, commercial maturity kits, neutral detergent fiber, and lignin). Compost N and C were evaluated during a 130 d aerobic incubation in a sandy loam soil. The effect of compost maturity on plant growth was evaluated by growing two ryegrass crops and one barley crop in succession in compost-amended soil under greenhouse conditions. Potential phytotoxicity from compost was assessed by growing tomato seedlings in compost-amended soil. The rate of N release from composts was srongly related to compost fiber and lignin concentration and to the Maturity Index, but not to total C, total N, and C:N ratio. Trends in C decomposition were similar. Ryegrass harvested 35 and 70 d after compost application was not strongly affected by compost maturity, and relatively immature composts were phytotoxic to tomato seedlings. Methods of characterizing compost maturity that more realistically reflect the composting process are better predictors of N release and potential plant inhibition after incorporation into soil.

Technical Abstract: Improved predictive relationships between compost maturity and nitrogen (N) availability would be helpful in managing these soil amendments as nutrient inputs. We collected 13 compost samples from a single windrow over a 91 d period, beginning when the compost met minimal National Organic Program standards. Compost maturity and stability were assessed using both standard chemical analyses (total C and N, mineral N, total volatile solids) and other methods (CO2 evolution, commercial maturity kits, neutral detergent fiber, and lignin). Compost N and carbon (C) were evaluated during a 130 d aerobic incubation in a sandy loam soil after each compost was applied at 200 mg total N/kg soil. The effect of compost maturity on plant growth was evaluated by growing two ryegrass (Lolium perenne L.) crops and one barley (Hordeum vulgare L.) crop in succession in compost-amended soil under greenhouse conditions. Potential phytotoxicity from compost was assessed by growing tomato (Lypersicum esculentum L.) seedlings in compost-amended soil. The N mineralization rate during the first 48 d of incubation was strongly correlated to compost fiber and lignin concentration and to the Maturity Index, but not to total C, total N, and C:N ratio. Trends in C mineralization were similar. Ryegrass harvested 35 and 70 d after compost application was not strongly affected by compost maturity, and relatively immature composts were phytotoxic to tomato seedlings. Methods of characterizing compost maturity that more realistically reflect the composting process are better predictors of N release and potential plant inhibition after incorporation into soil.