Presentation on theme: "Manure Composting: Opportunities and Challenges Katherine Buckley, PhD PAg Small Market Sustainability – Size Matters! Solid Waste Association of North."— Presentation transcript:
Manure Composting: Opportunities and Challenges Katherine Buckley, PhD PAg Small Market Sustainability – Size Matters! Solid Waste Association of North America/Canadian Public Works Association May 11-14, 2009 Winnipeg, Manitoba
odour from the storage transportation of nutrients nutrient application and accumulation issues flexibility in window for application public perception pathogens Challenges to livestock production partially mitigated by composting:
Manure composting challenges: Specifications/regulations for composting site (land requirements) Hauling distance from feedlot to composting site Suitable equipment Climatic effects Nitrogen retention Product quality and consistency, plant response Composting of low-solids manure and layer manure Deriving an economic value for compost use Acceptability for organic production (has to be derived from organically managed livestock) Behavior change in fertilizer use
Specifications/regulations for compost sites Lack of details for compost site construction –Every site is different – some have natural slope and underlying impervious layer –Some sites may require runoff collection, others might be better served by grassed strips that could be harvested to remove nutrients. –Requirement for security These specifications need to be consistently applied across the province
Clear guidelines are needed Locational criteria: –surface and ground water protection; distance from existing right–of-way; protection measures within a floodplain. Construction/Design Criteria: –Specify minimum requirements for pad surface; identify need for collection, containment, and use of all waters within the site confines. Operational requirements –Methods of operations at the facility; analytical data for leachate detection; manure (compost) management plan; control of public/animal access
Composting systems - In-vessel Aerated agitated bedRotating aerated drum High capital costs Not suitable for large livestock operation
Climatic effects Hot, windy weather results in need for additional moisture –Can result in decrease in moisture below a critical level for good compost activity –Difficult to rehydrate straw amended composts Extremely wet conditions result in need for frequent turning to restore porosity –Wet weather late in the composting process can result in a soggy product –Inability to turn wet compost can increase odour potential Cold, snowy conditions can hinder composting operation
Controlling climatic effects Curing and finished compost should be covered to prevent rewetting
Factors affecting nitrogen loss: total nitrogen content carbon content pH moisture temperature Nitrogen retention
Product consistency Compost properties, can differ greatly in NPK values, physical characteristics, salt levels, density and porosity. Characteristics depend on species, bulking agent and process intensity.
Factors affecting consistency of plant response The decomposition and mineralization of compost is dependent upon: Carbon content - lower decomposition rate at a high C:N ratio. Soil temperature – slower at low temperatures. Soil moisture – slower in dry soils. Soil texture - faster mineralization rate on sandy soils. Soil nutrient status - inherent fertility, pH and microbial diversity. A better understanding of multiple crop response to compost over time would improve marketing opportunities
Benefits of Composting (cont’d) Manure Composting Opportunities Pathogen and weed seed destruction Good source of phosphorus, potassium and micro-nutrients More predicable source of nutrients for crop production than raw manure Improved handling characteristics and transportation Improved soil quality Control of soil-borne plant diseases Improved economics of crop production
Physical changes during composting Water content Decreases from 70 to 30% Dry matter Mass loss of 20-30% Bulk density Increases 3-4 fold Implications for transportation of product!
Improved Handling and Application Apply the equivalent amount of manure as raw manure and as finished compost. (Larney et al., 1999) Fresh Manure Compost Wet wt: 22.3 t Wet wt: 7.9 t Wet BD: 0.3 t/m 3 Wet BD: 0.7 t/m 3 1 (10 m 3 ) Truck = 3.3 t 1 (10 m 3 ) Truck = 7 t # Truckloads = 7 # Truckloads = 1.1
Improved soil quality Reduced water erosion and soil crusting
Control of plant disease USA – potting mixes with composted animal manure suppressed diseases caused by Pythium and Rhizoctonia. Spain – field trials with composted chicken litter reduced root-knot nematodes in tomato and pepper plants. Canada – early indications that cattle manure composts may suppress potato diseases.
Control of plant disease Mechanisms of action: Competition for nutrients Secretion of antibiotics for suppression of disease. Parasitism of plant pathogens and consumption. “Systemic acquired resistance” may occur, where plants grown in compost have a higher level of an enzyme associated with disease resistance.
Control of plant disease The composting process must be done properly to obtain a disease-suppressive product: a poorly composted product will actually increase the risk of disease, while an over-mature product has little microbial activity. Future research will provide guidelines on using composts for disease control. It is expected that “inoculated” composts will become commercially available to prevent specific diseases in specific crop situations.
Economic value of compost Increase in soil aggregate (crumb) stability → improved water absorbing capacity and permeability during heavy precipitation → higher moisture reserves during drought. Compaction protection, increase of soil resilience → improved traffic tolerance → decrease in draft weight and fuel. Enhanced soil biological activity → increased mineralization. The quantity of N, P, K, Zn, Cu and other trace elements. Value of compost ~ $200/tonne
Acknowledgements Agriculture and Agri-Food Canada “GAPS” program Manitoba Conservation “WRAPP” program Manitoba Rural Adaptation Council Western Grains Research Council Manitoba Agriculture Food and Rural Initiatives “Green Cover” program