STABILIZING CATTLE FEEDLOT SOIL WITH FLUIDIZED BED COMBUSTOR ASH

Abstract

Many cattle feedlots are operated on bare soil because it is expensive to cover the entire lot with concrete. During heavy rainfalls, feedlots built on clay-rich soils often become muddy as their soils lose strength. These soils cannot support the weight of animals or equipment. As a result, the animals’ rate of gain suffers, and feedlot management becomes difficult. Fluidized Bed Combustor (FBC) ash from the Iowa State University Physical Plant was used to produce a significant increase in soil strength on a cattle feedlot near Nevada, Iowa. FBC ash is the residue from burning high-sulfur coal in fluidized bed combustors. Limestone (calcium carbonate) enters the combustor with the coal as a sorbent to reduce sulfur dioxide emissions. FBC ash is considered a “nuisance” waste, and the cost for disposal exceeds US$20 per metric ton.Stabilizing cattle feedlot soil with FBC ash represents a recovery of resources because the ash, when combined with clay soil and water, has cementious properties. Research was conducted with three objectives: (1) to determine whether FBC ash can be used to increase the strength of feedlot soil when applied at a level of quality control attainable by using ordinary agricultural tillage equipment; (2) to compare feedlot soil stabilized with FBC ash to non-stabilized feedlot soil in both laboratory and field tests; and (3) to develop a low-cost alternative to paving a feedlot with concrete. Field results from a feedlot treated with FBC ash show that soil strength was improved 200% to 300% when compared with an adjacent untreated feedlot.