Maintaining a good soil for plant growth requires some effort. Regular additions of organic matter, such as compost, manure or crop residues are necessary.
Organic matter provides energy for biological activity. It also attracts and holds plant nutrients in an available state, reducing the amount of nutrients lost through leaching. It improves soil structure, so that air reaches plant roots and the soil retains moisture. Well-rotted composts and manures also suppress plant diseases by boosting the population of soil microorganisms that compete with disease-causing organisms.