Manure may be defined as the materials of plant and animal origin under varying stages of decomposition, which on application to soil can improve the soil characteristics. It is generally organic in nature.
Organic matter is any accumulated biological debris, crop and animal residues such as leaves, stem, and animal byproducts. The amount retained and incorporated into the soils depends on temperature, moisture, aeration, microbial activities and soil pH as well as the quantity and chemical makeup of the materials.
There is always more organic matter near the surface and less at lower soil.
Soil organic matter refers to the non-living materials in soil coming from plants, animals, microorganisms and which occupies 5% of total soil volume.
When organic matter completes its process of decomposition all that is left back or dark coloured material is known as humus.
Or Humus bay be defined as the highly decomposed organic matter which is fairly stable, amorphous, brown to black material formed as a result of decomposition of plant and animal residues.
Fertilizers are the chemical substances manufactured in the factories and are used to supply one or more nutrient elements to the soil for successful crop production.
Or any chemical compound, which is used to supply one or more essential plant nutrients, is known as fertilizer. It is generally inorganic in nature.