Biosolids Application to No-Till Dryland Agroecosytems

Dryland agroecosystems are generally ideal environments for recycling biosolids. However, what is the efficacy of biosolids addition to a no-till dryland management agroecosystem? From 2000 to 2010, we studied application of biosolids from the Littleton/Englewood, CO Wastewater Treatment Plant versus commercial nitrogen fertilizer in dryland no-till wheat (Triticum aestivum, L.)-fallow (WF) and wheat-corn (Zea mays, L.)-fallow (WCF) rotations at a site approximately 50 miles east of Denver, CO. We tested if biosolids would produce the same yields and grain phosphorus, zinc, and barium concentrations as an equivalent rate of nitrogen fertilizer, that biosolids-borne phosphorus, zinc, and barium would not migrate below the 4 inch soil depth, and that biosolids application would result in the same quantity of residual nitrate-nitrogen as the equivalent nitrogen fertilizer rate. Biosolids and nitrogen fertilizer produced similar wheat and corn yields; but, biosolids application resulted in smaller wheat grain barium due to the soil formation of barium sulfate. Biosolids application produced greater soil nitrate-nitrogen concentrations than nitrogen fertilizer in the 1 to 2 foot and 2 to 3 foot depths for the WF rotation and all but the 2 to 4 inch and the 4 to 5 foot depths for the WCF rotation. We concluded that biosolids application in a no-till managed dryland agroecosystem is an efficacious method of recycling this nutrient source