A Windrow That Will Not Heat: Manure, Olive Pomace and Broiler Litter
A cooperative in the Limassol hills has 40 t of sheep manure mixed with straw bedding and 15 t of two-week-old olive pomace. They built windrows 3 m wide and 1.5 m high on bare soil in late October. After 18 days the core temperature is 38-42 C and there is a strong ammonia smell; the material is dry and crumbly at the surface but sticky and grey-green inside. The mixture was estimated at C:N 32:1 but no moisture test was done. They plan to spread it in February on 1.5 ha of lettuce and 2 ha of young olive trees, and to sell some bagged compost. A neighbour offers free broiler litter from an intensive poultry house. The cooperative's organic inspector says the compost must be mature and the manure source documented.
1. Diagnose why the windrows failed to heat and describe the rebuild, including the temperatures and turning regime you would require.
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This is slow rotting, not composting. Surface dryness with a sticky grey-green core, 38-42 C and ammonia point to four causes: moisture below the 50-60% target, so microbial activity is limited; particle size too large (long straw, coarse pomace), reducing surface area; poor aeration because the windrow was not turned and sat on bare soil; and nitrogen loss as ammonia, which happens when high-N manure is mixed with too little carbon and pH is high.
Rebuild: chop material to 2-5 cm; re-mix towards C:N 25-30:1, adding straw or woodchip to the pomace and manure; add water until a squeezed handful holds together without dripping; form windrows 2.5-3 m wide and 1.2-1.5 m high on a firm pad with a coarse base layer for drainage and air; cover with breathable fleece to keep rain off while allowing air through.
Turn when the core reaches 55 C, or after three days, moving outer material into the core. Target 55-65 C for at least three consecutive days across the whole mass for hygienisation, then three or four more turns over six to eight weeks. Monitor at three points per 10 m and record the readings. If it still fails to heat, test moisture and C:N before adding anything else; adding more nitrogen will only increase ammonia loss.
2. Decide whether the compost is suitable for the February lettuce crop and explain how maturity, timing and nutrient budgeting should be handled.
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Immature compost is risky on lettuce. Continued decomposition releases ammonia and organic acids, can immobilise nitrogen and burn seedlings, and pathogens may survive if the temperature target was never reached. Maturity indicators are: ambient temperature after turning, earthy smell with no faecal or ammonia odour, C:N below 20, dark crumbly texture, and a cress germination test above 90% with no root shortening. Test before use rather than judging by age.
Timing: apply mature compost three to four weeks before transplanting or sowing, incorporate it into the top 10-15 cm and irrigate so the material stabilises. For lettuce, no raw manure and no compost that has not been hygienised. Keep a nutrient budget: 40 t over 3.5 ha is about 11 t/ha; at 5-7 kg total N/t that is 55-80 kg N/ha, which is reasonable, but first-year N availability is only 10-20%, so do not assume the crop is fully supplied.
Record source, dates, quantities and any analysis. If maturity is doubtful, use that batch on the olives and buy certified compost for the vegetable beds. Selling bagged compost also requires a consistent, tested product, so keep batch records and a labelled analysis.
3. The neighbour offers free broiler litter. Decide whether it can be accepted and what conditions and checks apply.
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It cannot be accepted automatically. Under Reg. (EU) 2018/848, manure from non-organic holdings may be used only under the conditions in Annex II and national rules, it must not come from factory farming (which excludes cage systems), and it must be treated or composted as the control body requires. Source, quantity and dates must be documented.
Broiler litter from an intensive house is also a biosecurity and residue risk: it may contain coccidiostats, antibiotic residues, feathers and high salt, and it is a strong ammonia source. Ask for a written declaration of the production system, confirmation of no cage housing and no growth promoters, and the feed and additive history. Compost it separately for at least eight weeks with a carbon source, reach 55-65 C and test it. Do not spread it on lettuce.
If the documentation is inadequate, refuse it: a cheap input is not worth the certification risk. Also check the Nitrates Directive limit of 170 kg manure N/ha/year for the whole holding before adding another manure stream, and remember that the 40 t already stockpiled counts toward that budget.