Why is soil that is rich in humus important to farmers?

The addition of humus to the soil has physical and chemical effects. Physically humus absorbs and detains moisture; it raises the temperature of the soil and maintains it in an equable condition; it keeps the particles of sand and clay asunder and therefore improves the aeration and porosity; it detains the heat, and thus prevents the roots of plants being frozen during hard frost. But humus performs other important functions in the soil, especially in connection with the nutrition of many trees and shrubs and crenelate plants generally

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