Plant-Available Phosphorus from Distillers By-Products.

A 56-day incubation was conducted to determine the availability of plant-available P from corn ethanol condensed distiller’s solubles (CDS) with or without the presence of corn (C) or soybean (SB) residue. Average P availability as determined by NaHCO3 extraction (Olsen P test) ranged from 13 to 103 ppm and ranked: soil + C residue + CDS > soil + SB residue + CDS > soil + CDS > soil + C residue ≥ soil + SB residue = soil. Over the 56-day incubation period, the highest average extractable P was at day 0 with 91 ppm P while the lowest was at day 10 with 37 ppm P, respectively. The extractable P levels then increased to nearly 65 ppm at day 56. The data suggests that the CDS contains high levels of ortho-P which appears to be microbially immobilized early in the incubation period but is later remineralized as microbial populations turn over. Implications of using distiller’s CDS as a nutrient source for crops will be discussed.