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

Abstract

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 CO2-C evolution over a 37-day period. Fly ash applications of 400 and 700 tonne ha-1 reduced CO2-C production significantly compared to 0 and 100 tonne h a -1 treatments. Carbon dioxide-carbon from all treatments was considerably greater than that from soil treated with 1000 ppm CdC12. 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.

Reclamation and revegetation of fly ash disposal sites – Challenges and research needs

“…Although acidic ash (pH 3.5-5.0) seems to have less of an inhibiting effect on microbial activity than alkaline ash (Pichtel, 1990), inhibitory effects on respiration have still been noted (Arthur et al, 1984;Pichtel, 1990). These effects were attributed to toxic levels of available trace metals which become available at low pH (Arthur et al, 1984).…”

Analysis of Coal Ash for Trace Elements and their Geo-environmental Implications

“…Arthur et al (1984) reported significant reductions in microbial respiration upon fly ash addition in soil to trace metals present at potentially toxic concentrations. The microorganism removal also ceases detoxification of trace elements by enzymatic reductive processes.…”

The Effect of Fly Ash Application at Cultivation of Spring Wheat on Chernozem Soils of Northern Kazakhstan

“…Data obtained by Cerevelli, Wong and Pitchel [24][25][26] show that the application of fly ash significantly improves not only the aeration of the soil and the activity of enzymes but enhances also the nitrogen cycle processes in the soil such as nitrification and mineralization. However, Arthur has revealed that excessive application rates of ash (400-700 t/ha) have a negative impact on microbiological activity 27 .…”