Trouble-shooting Small-Scale Compost Systems R. Henry, and R. D. Peters Agriculture and Agri-Food Canada, Crops and Livestock Research Centre, 440 University Ave., Charlottetown, PE C1A 4N6
Project Objective High quality compost Waste management Specialty compost
Common Problems Air / oxygen or lack of it Moisture excess or not enough Carbon - amount relative to Nitrogen; C:N ratio Nitrogen too much or not enough Pile porosity ph Phosphorous Equipment required vs available Site preparation and selection
Carbon Required by the microbes to use up the Nitrogen in the feedstocks such as manure/food waste, fish etc Lack of carbon will cause odours Some types of carbon more available than others Amount of carbon varies; 250 : 1 down to 5 :1 Start-up require a ratio of 25 40 : 1 Availability of carbon depends on source Molasses leaves straw wood materials Different characteristics to final product
Sawdust C:N 250:1 Issues
Alternative Carbon Sources Peat C:N 200:1 Paper Mill Sludge C:N 250 :1
C:N Ratio of Feedstocks Straw 80 :1, will be slow to rot on its own as not sufficient N to rot quickly Hay 25:1, once hay is wet, rots quickly as hay has about 25 parts C to each part N.
Know Your Feedstock Sources Analyze all ingredients unless familiar with the material Detailed analysis of all new ingredients should include: Dry matter Carbon and Nitrogen C:N ph Other major nutrients possibly are deficient Minor nutrients not an issue other than to know them (Mo) Heavy metals Other contaminants
Know Your Feedstock Sources Availability of each, carbon often an issue Effects of each on the final product Additional requirements, containment of odour, liquid waste Contamination with unwanted materials
C:N Ratio Parts C to Parts N or %C / %N 25:1 ideal for initial mix of raw ingredients 40:1 max for initial mix of raw ingredients Need below 20:1 to ensure will not tie up N in the soil 15:1 will release ½ the nitrogen that season Hay 25:1, once hay is wet, rots quickly as hay has about 25 parts C to each part N. Straw 80 :1, will be slow to rot on its own as not sufficient N to rot quickly
Wood waste carbon sources Contain most carbon of all sources Very good at absorbing liquid Very good at absorbing odour Will take longer to breakdown Likely require addition of more N later in the process, When completed will loose the sawdust texture Porosity varies
Pile Formation What options are available? Loader, manure spreader, specialized eq.
Specialized Equipment used to form piles or windrows Lobster Potatoes
Seafood Compost @ 35 days 44 C, with good odour and texture Day 12 no heat, added water and more waste Turned twice weekly for aeration
Making a potato based compost, with wood waste Lay down 12 inch layer of straw Add 18 inches of sawdust Trench sawdust, add potatoes
Potato based compost Top with manure or woodash Turn 3-4 times to chop and mix
Potato based compost @ 35 days pile wet, 30 C, higher C:N Requires more N and address moisture More potatoes requiring disposal Added dry grass clipping help the N and moisture
Moisture levels of compost Moisture - 60% + pile will start to go anaerobic and there will be some leachate at pile base Moisture - less 40% the pile is too dry and microbes stop Ideally one should be set up to add water, generally people do not take the time Squeeze test
Site Selection and Preparation Seasonal or year round Base Slope Leachate Collection Important to have site set up before feedstocks arrive!
Water Problems Piles too close Poor Site
Site on high ground low fertility part of field Pile shape, size and structure?
Temperatures during composting Heat - measure of microbial activity - 30 C composting very slow - Low loss of N and C - 55 C+ ; very active composting - potential for high amount of Carbon and Nitrogen loss - Over 40 C; kills weed seeds - 55C for 3 days; pathogen kill
Good working pile water needs, time of year?
Amount of turning required
Too Dry high porosity, good N, no available water
Compost Maturity Colour Odour Texture C:N ratio Reheating potential
Compost Maturity More mature, more humus, less raw manure/o. m. More mature, less odour, darker in colour, more options for use, pastures & field crops 3 Month old 9 Month old
Nutrient Content of Compost Generally assume compost is 50% water Results of lab analysis are either on as basis or dry matter basis Average values on as is basis are: N.35 1 % P.25 -.50 % K.10 -.80 % Special feedstock can increase other nutrients, shellfish high Ca, cardboard high B, woodwaste high Mo
Using Compost -- Potato Yield (tonne/ha) Banded Treatment 2002 2003 Broadcast 2002 2003 Compost 20.9b 18.5a 19.6b 17.6a Fertilizer 29.5a 21.9a 25.5ab 19.8a Raw Lob waste 6.6c 24.3a 30.0a 19.9a
Using Compost -- Additional Benefits Waste management Soil Health Disease suppression Mean severity of black scurf - NOVEMBER (% of potato tuber surface covered) Compost Banded Compost Broadcast Fertilizer Banded Fertilizer Broadcast Raw Broadcast 3.9 ab 5.0 a 5.0 a 5.7 a 3.0 b
Possible mechanisms of disease control antimicrobial properties stimulation of host resistance mechanisms enhance complement of beneficial bacteria and fungi
Blessings to all