Humus

vegetable mold. Humus is commonly of a dark brown or black color. It is produced by the decay of vegetable matter exposed to little air. Soils otherwise rich require the presence of humus to become productive. Earth partly composed of forest leaves or half rotten turf is rich in humus. Florists prefer usually sand in their flowerpots and greenhouses, but they heap up huge piles of thin sod and allow it to decay as an enriching material. It supplies the humus required by the roots of plants. The farmer dresses his fields with barnyard manure. As it undergoes decay this litter adds a coarse humus to the soil. Old straw decaying underground furnishes a supply of this desired ingredient. See Soil; Clover; Agriculture