Fly ash as a soil ameliorant for improving crop production--a review.

Among traditional fossil fuel sources, coal exists in quantities capable of supplying a large portion of our future energy needs. According to the President's National Energy Plan, annual productions of 1.2 × 109 t by 1989 and 1.91 × 109 t by the year 2000 are anticipated. It appears reasonable to expect an increase in the percentage as well as the number of coal‐fired power plants. The increased use of coal will produce additional quantities of fly ash, one of the waste products of burning pulverized coal. Fly ash constitutes about 70% of the total amount of residue generated in coal‐fired power plants equipped with electrostatic precipitators or bag filters. Fly ash contains various substances of which trace metals, although present in a small fraction, are of special interest due to their cumulative build up, long life, and high toxicity to man, plants, and animals through air, water, and soil. Several estimates made by the Bureau of Mines suggest that the fly ash released into the atmosphere appears t...

Fly ash dynamics in soil‐water systems

Restoration of drastically eroded land using coal fly ash and poultry biosolid.

Unweathered, acidic fly ash from a coal-fired power plant was applied to alfalfa meal-amended agricultural soil at levels equivalent to 0, 100, 400, and 700 tonne ha−1. Amended soils were placed in respirometer jars and monitored for C02-C evolution over a 37-day period. Fly ash applications of 400 and 700 tonne ha−1 reduced C02-C production significantly compared to 0 and 100 tonne ha−1 treatments. Carbon dioxide-carbon from all treatments was considerably greater than that from soil treated with 1000 ppm CdCl2. The results suggest that soil heterotrophic microbial activity may be impacted minimally by relatively low levels of fly ash application, but may be inhibited by higher levels of fly ash. Several metals were present at potentially toxic levels in the fly ash employed and may have accounted for the inhibition of CO2 C evolution. The availability of some of these metals was indicated in companion plant uptake experiments.

Effects of fly ash on microbial C02 evolution from an agricultural soil

Huge quantities of solid wastes are generated as a result of mining and mineral processing activities in the United States. Over the years, the majority of these by-products have been disposed of in unsightly dumping areas which are aesthetically unattractive and often degrading to the environment. However, many of these wastes, because of their similarity to conventional soils and aggregates, represent potentially useful sources of material for a variety of applications.

L.M. Adams

Papers

Reclamation of acidic coal-mine spoil with fly ash