ABSTRACT
Plant nutrients can be subdivided into major nutrients and minor or micronutrients. Three of the major nutrients, nitrogen, phosphorus, and potassium, are the most important and are utilized to the greatest extent. These three plant nutrients are the ingredients listed on fertilizers sold at stores. When biosolids are incorporated into the soil, the organic matter immediately begins to decompose by the microbes in the soil or those in the biosolids, as long as temperatures are above freezing and there is sufficient moisture. Even at low temperatures and under drought, decomposition proceeds at a very slow pace as a result of the heat and moisture of the decomposing organisms. Microorganisms utilize the carbon as a source of energy, and the nitrogen for cell development and growth. When biosolids are applied to land, the predominantly organic nitrogen undergoes numerous transformations. Immobilization is the tying up of nitrogen by soil organisms.
