Biosolids is now widely being used for crop production in the United States. In fact, nearly half of the production of biosolids in the United States is being used to benefit soils—add much-needed nutrients like nitrogen, potassium, and phosphorus. However, most are being confused by what “land application” means and what regulations does it fall under.
In a nutshell, land application is the application of biosolids to land with the purpose of conditioning the soil for plant use or fertilizing crops or growing vegetation. Biosolids in the United States can either be applied and sold in bulk for large-scale manufacturers of organic products or in bags for smaller units of land such as lawns and home gardens.
Generally, biosolids is applied on agricultural land, forests, and reclamation sites or collectively called nonpublic contact sites. This means that these are areas not frequented by the public. The material can also be applied on public parks, plant nurseries, roadsides, golf courses, lawns, and home gardens or public contact sites. These are areas frequented by the public.
However, the EPA or the Environmental Protection Agency does not regard lawns and home gardens as public contact sites. In fact, there are only a number of biosolids that can be applied on lawns and home gardens. For example, CPLR biosolids cannot be applied on home gardens because of the difficulty in tracking cumulative levels of metals in biosolids applied to such sites.
There are a number of techniques for the land application of biosolids. Among these are spraying or spreading the material on the soil surface (for pastures, lawn, or range and forest land) or tilted into the soil (for producing row crops and other vegetation and for establishing lawns).
If the biosolids is in a liquid state, it can be applied with the use of tractors, tank wagons, irrigation systems, or special application vehicles. On the other hand, dewatered biosolids makes use of the same equipment used to apply commercial fertilizers, animal manures, or limestones. Liquid and dewatered biosolids can be applied to land without previous or subsequent incorporation into the soil.
Applying the biosolids directly into the soil and even incorporating them into the base layers of the soil is safe for crop and food production and even vegetation. The EPA Part 503 Biosolids Rule made sure of this through various government regulations on the application of biosolids, especially as it refers to the direct contact on land used for crop production and farming.