Biosolids are an excellent fertilizer. They are high in nutrients, organic matter and are stringently tested on a quarterly basis to ensure high quality. Biosolids are hauled, at no charge, injected evenly throughout a field and spread at a rate to meet the nitrogen need of the next crop. Corn for instance can receive up to 145 lbs. of nitrogen per acre, minus any nitrogen residual.
The nutrient phosphorus is also found in biosolids. Although, beneficial for crop production, field runoff containing phosphorus should be controlled. If runoff containing phosphorus finds its way into a stream or lake, unwanted algae blooms may result. This is more of a concern for land that has been fertilized with manure or commercial fertilizer. In these forms, the phosphorus is found to be in a soluble in water state. However, in biosolids, the phosphorus binds itself organically to the soil as it is injected into the soil, and is found to be insoluble in water. Therefore, when biosolids are applied to these approved farm sites, phosphorus runoff is of little concern.
Biosolids application has changed through the years. Instead of a large field tanker being pulled back and forth through a field, a dragline method is now used to minimize soil compaction. Low-till discs are also used to incorporate the biosolids into the ground instead of plows to minimize disruption of the soil.
Fields that receive biosolids must first be qualified through the Wisconsin Department of Natural Resources (DNR). In general, fields that are dry with little or no slope and away from residences and bodies of water usually qualify. Biosolids cannot be applied to areas of a field with a high water table or having greater than a 6% slope. Required setback distances do not allow biosolids to be applied within 25 feet from a property line, 200 feet from a residence, 250 feet from a private well or 100 feet from surface water. Also, the pH of the soil must be neutral. A recent soil test must show the pH to be at least 5.5 or higher.
The guidelines outlined above are in place to ensure safe utilization, minimize the chance of runoff and maximize the fertilizer benefit. If you are a landowner within 15 miles of Marshfield, WI and would be interested in receiving biosolids on your acreage, call Marshfield Wastewater Treatment Facility at (715) 486-2007.