To view these files, it may be necessary to download the Adobe Acrobat Reader. Biosolids are, in effect, a slow release nitrogen fertilizer with low concentrations of other plant nutrients. In addition to significant amounts of nitrogen, biosolids also contain phosphorus, potassium, and essential micronutrients such as zinc and iron.
Many western soils are deficient in micronutrients.
Biosolids are rich in organic matter that can improve soil quality by improving water holding capacity, soil structure and air and water transport. Proper use of biosolids can ultimately decrease top soil erosion. Colorado State University agronomists have shown continuous application of three dry tons per acre every other year to dryland wheat produces comparable yields, higher protein content, and larger economic returns compared with the use of 50-60 pounds per acre of commercial nitrogen fertilizer. Most simply, biosolids is the new name for what had previously had been referred to as sewage sludge. Sewage sludge now refers to untreated primary and secondary organic solids.