A tunnel is filled 2 to 2.2 metres deep at about 900 to 1000 kg per square metre, with air pushed up from the plenum below. ICAR-DMR insists that the air above the compost, the compost itself and the plenum differ by no more than 3 °C, or one layer is under-pasteurised while another is over-cooked. On a small farm, probe a covered heap top, middle and bottom.
Finished compost has ammonia below 10 ppm, moisture around 64 to 66 percent with no liquid oozing when squeezed firmly, and a dark crumbly texture.