Answer:
28 true. Humus: the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.
29 false, Soil organic matter is the fraction of the soil that consists of plant or animal tissue in various stages of breakdown (decomposition). Most of our productive agricultural soils have between 3 and 6% organic matter. Soil organic matter contributes to soil productivity in many different ways.
