material, such as wood chips, added to compost primarily to help create good pore structure for air flow. Often provides part of the carbon source as well.

            H - M

bringing about the contact of the compost with air through turning, or ventilating to allow microbial aerobic metabolism.

occurring in the presence of oxygen. For successful composting, sufficient oxygen should be provided to keep the system aerobic. This ensures that the composting proceeds rapidly and with minimal odour.

temperature outside the compost pile.

occurring in the absence of oxygen. Anaerobic composting proceeds slowly and is odiferous.

the potential of an organic substance to be broken down into simpler compounds or molecules through the action of microorganisms.

the mass of a unit volume of soil, generally expressed in gm/cm3. The volume includes both solids and pores. Thus soils that are light and porous will have low bulk densities, while heavy or compact soils will have high bulk densities.

a measure of the negative charge on soils (primarily on clays and organic matter). It is expressed as the quantity of cations (positive ions) that can be adsorbed by the soil and is expressed in centimoles of charge/kg of soil (6x1023 charged particles are contained in one mole of charge).

unwanted material. Physical contaminants of compost include glass, plastic, and stones, and chemical contaminants include trace heavy metals and toxic compounds.