Thirty faults, in alphabetical order

Troubleshooting index

Every fault recorded at this bench: what it looks like, why it happens, and the sequence of things to do about it. Most are fixed by changing one variable and waiting three days.

01 Ammonia smell Too much nitrogen relative to carbon. The pile is releasing nitrogen as ammonia gas instead of fixing it into microbial biomass — common with blood… A sharp, cleaning-product smell at the vent or when the lid is opened, often strongest in the first week.
02 Bokashi bucket smells rotten Putrefaction has overtaken the lactic fermentation. Usually too much liquid in the bucket, too little bran, or the lid has been left off long enough… Rotten eggs, sewage or a strong faecal smell when the bucket is opened, instead of the expected pickle smell.
03 Buried bokashi still sour after weeks Cold soil, heavy clay, or a trench that is too concentrated. Fermented waste needs soil contact and microbial activity to neutralise, and both are… Digging into a bokashi trench after three or four weeks finds recognisable, sharply acidic material.
04 Cold zones found at screening The dry outer shell never entered the hot core on any turn — typical of wide windrows and of piles turned in place. Undigested material with original colour and structure appears at screening, usually from one side of the pile.
05 Disease appearing after using compost Diseased foliage composted in a cold pile or left on the outside of a hot pile, where temperatures never reached the level needed to kill the… Blight, clubroot or damping-off appearing in beds that were dressed with compost containing diseased plant material.
06 Dry outer shell Surface evaporation exceeding the moisture the material can hold. In a windrow this shell can be 15 % of the total volume. The outside 20-30 cm of the pile is dry, light-coloured and unchanged after months, while the core is finished.
07 Finished compost reads pH below 6 A feedstock dominated by fruit waste, coffee grounds or pine needles, and a pile that never exceeded 40 °C, so the organic acids were never broken… A pH meter reading of 5.2-5.9 in finished compost, and poor germination when it is used in a seed mix.
08 Fruit flies around the worm tray Food left on the surface. Fruit flies lay on exposed material and complete a generation in about a week, so a surface feed becomes an infestation… Small flies in the air around the tray, and maggots in any food that is sitting on the surface.
09 Grass through the cardboard seams Overlaps under 15 cm, or sheets laid on uneven ground so that one edge lifts. Grass finds the gap and grows toward the light. Tufts of grass pushing up through the joins in a sheet-mulched bed within four to six weeks.
10 Material balls up in a tumbler Wet kitchen waste without enough dry structure, and over-filling the drum so the contents rotate as a block instead of tumbling. 10-15 cm balls of wet material visible through the hatch, a sour smell at the vent, and a temperature stuck around 40 °C.
11 Matted clumps that will not break up Grass clippings, wet leaves or kitchen waste added in layers thicker than 10-15 cm without being mixed. The outer surface dries and seals while the… Grapefruit-sized or larger balls of material that survive turning and are soggy inside.
12 Mould on material in storage Anaerobic consumption in storage. The material is not composting, it is rotting, and it is losing the sugars and nitrogen that made it a good… A white-grey mould film on coffee grounds, kitchen waste or manure that has been sitting in a sealed bucket for a week.
13 No white mould on the bokashi surface Usually one of three things: the bran is old and the inoculant has died, the bucket is too cold (below 10 °C), or the waste was too dry for… After two weeks the surface shows no white fungal film and the contents look unchanged.
14 Pile is dry and crumbly Moisture below 40 %. Most often caused by using far more dry browns by weight than intended, because they look damp while containing 8-14 % water. The material crumbles rather than clumps, the surface looks dusty, and the temperature is below 40 °C.
15 Pile is frozen solid A small mass, above 65 % moisture, exposed to sustained frost. Ice fills the pore space and biological activity stops rather than merely slowing. The pile is rigid, cannot be forked, and shows ambient or below-ambient temperature at the core.
16 Pile is too dense to aerate Fine, uniform material — sawdust, screened compost, wet manure without structure — packed so there are no air channels. A fork goes in with difficulty, the material feels heavy and clay-like, and the pile heats unevenly or not at all.
17 Pile runs above 70 °C Very large mass, high nitrogen and 55-60 % moisture together. Above 70 °C the useful thermophilic community dies off, nitrogen volatilises and the… Core readings above 70 °C, a sharp smell of scorching, and visible white ash-grey microbial bloom.
18 Plants yellowing after compost or chip mulch Nitrogen immobilisation. High-carbon material dug into soil feeds the microbes that break it down, and they take nitrogen from the surrounding soil… Pale, yellowing lower leaves and stalled growth within two to four weeks of applying wood-based compost or digging in fresh chips.
19 Rodents digging in the pile or bed Food waste left within 20 cm of the surface, or added to an open heap or sheet-mulched bed where animals can reach it. Holes in the side of a heap or in a mulched bed, and food waste visible on the surface.
20 Slimy grass layer Grass added in layers thicker than 15 cm. Fresh clippings seal the surface of a layer within 36 hours and the interior goes anaerobic. A black, slippery layer of grass in the middle of the pile, with a sewage-like smell when it is broken open.
21 Sour or rancid smell Anaerobic conditions. The material has compacted or matted, air can no longer move through it, and acid-producing bacteria have taken over from the… A vinegar, silage or rancid-butter smell, usually with a temperature drop of several degrees.
22 The pile will not heat In order of likelihood: the pile is too small (under 0.9 m³), too dry (under 40 % moisture), too carbon-heavy (over 50:1), or the pieces are too big… Temperature sits within 5 °C of ambient for a week or more. The material looks fine and does not smell.
23 Twisted growth in beds dressed with compost or manure Aminopyralid or clopyralid residue from treated hay, silage or lawn, passed through the animal or through composting and still active in the… Tomato, bean and pea plants with curled, cupped or fern-like new growth, and pods that are deformed or empty.
24 Water pooling in the bin Moisture above 70 %, usually from wet manure or kitchen waste with insufficient carbon, and from no drainage in the container. Liquid visible at the bottom of the bin or in the fork holes, and the lower material is slimy.
25 Weed seedlings in finished compost The pile never held 55 °C for three consecutive days, so seeds survived. Common in cold piles, tumbler batches and piles turned too rarely. Weed seedlings germinating in beds dressed with compost that was cold-composted or never exceeded 55 °C.
26 Wet, sour layer at the base Water draining to the base and no air movement at the soil interface. Common in piles built on concrete or on a compacted surface. The lowest 15 cm of a ground pile is dark, wet and sour-smelling even when the rest of the pile is fine.
27 Whole blocks compacted at the bottom Material added in intact blocks — mushroom substrate, sod, whole root balls, unopened cardboard — without being broken up. The centre of each block… A grey, sour, slimy brick of material found at the base of the bin when it is emptied, with a distinct boundary against the rest.
28 Winter pile never starts Microbial activity roughly halves for every 10 °C drop. A winter pile needs a larger mass, a warm water charge and insulation to reach the… A pile built in November or December sits at 10-15 °C for six weeks or more.
29 Worm tray has gone wet and smells Overfeeding with wet material and not enough dry bedding. Kitchen waste is 80-84 % water and a tray with no carbon to absorb it becomes anaerobic. Liquid at the bottom of the tray, bedding that drips when squeezed, and a sour or ammonia smell.
30 Worms climbing the walls Conditions have become intolerable: too wet, too acidic, too hot (above 28 °C), or a protein-rich feed has heated and soured. Worms leave rather… Worms massed on the inside walls and under the lid, or found dead on the floor around the tray.

If a fault is not here, it has not happened at this bench yet — the list grows when one does.