Often, the soil doesn't hold enough of these nutrients in the quantities needed for desirable growth and production. The nutrients, that are in the soil, are often used up and need to be replaced. Nutrients, such as nitrogen, are easily leached by water and can also be volatilized into the atmosphere. These nutrients are usually not available, in sufficient quantities, from the soil. We add these nutrients by applying fertilizer.
Fertilizer is any material that supplies one or more of the essential nutrients to plants.
Organic fertilizers are derived from living or once living material. These materials include animal wastes, crop residues, compost and numerous other byproducts of living organisms. Several considerations should be made before deciding on a fertilizer choice. First of all, you need to consider the nutritional needs of the crop for optimum performance. Secondly, you need to have you soil analyzed to see what is available in the soil.