Plant nutrition is the study of absorption, translocation, and function of essential elements or nutrients in plants. Essential elements are chemical elements that meet criteria that determine that the elements are required for plant growth and development and therefore are called plant nutrients. Soil fertility is the study of delivery of essential elements from the soil to the plant. Soil fertility involves chemical, physical, and biological properties of soils. Some chemical properties of soil fertility are supply of plant nutrients and soil acidity. Some physical properties that affect soil fertility are texture, structure, depth, drainage, aeration, water, and temperature. Biological properties refer effects of organisms on soil fertility and may include harmful organisms such as diseases, insect pests, and weeds or beneficial organisms such as bacteria that conduct processes of mineralization and nitrification. It is difficult to sort properties of soil fertility into chemical, physical, and biological factors because of the interrelations and similarities of these factors.