|Tarkalson, David - UNIVERSITY OF NEBRASKA|
|Hergert, Gary - UNIVERSITY OF NEBRASKA|
|Mccallister, Dennis - UNIVERSITY OF NEBRASKA|
|Kachman, Stephen - UNIVERSITY OF NEBRASKA|
Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 27, 2004
Publication Date: May 15, 2005
Citation: Tarkalson, D.D., Hergert, G.W., Stevens, W.B., Mccallister, D.L., Kachman, S.D. 2005. Fly Ash as a Liming Material for Corn Production. Soil Science. 170:386-398. Interpretive Summary: Fly ash produced as a by-product of sub-bituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was conducted to determine if fly ash produced from the Nebraska Public Power District Gerald Gentleman Power Station located in Sutherland, NE could be used as an alternative liming material. This study had the following objectives: (i) Compare the effects of fly ash on soil pH with other common agricultural lime materials; (ii) determine the effects of fly ash on percent Al saturation in selected soils; and (iii) determine the effects of fly ash on corn grain yields. Results show that fly ash with properties similar to that produced at the Gerald Gentleman Power Station is an acceptable alternative liming material when applied at the rates approximating the recommended rate. No negative effects of fly ash on corn grain yields were observed in this study. The lack of positive corn grain yield response from added lime materials is potentially a result of one or combination of four issues: (i) lack of sufficient lime additions to raise the soil pH to a level in which a response would have been seen, (ii) lack of sufficient tillage to incorporate lime, (iii) higher subsoil pH negated negative effects of surface soil pH, and (iii) soluble Al concentrations in these acid soils were not sufficiently high to reduce yields. Corn is less responsive to changes in pH or soil Al concentrations present in this study. None of the lime materials raised soil pH to the target of 6.5, but continued research is needed to determine the reason for the lack of predicted pH increase at these sites. All the lime materials increased soil pH on all soils, but the differences were not always significant. The increase in pH on the limed treatments above the control took place in the first year of application on the Anselmo, Holdrege, and Hord sites. There were no consistent differences in soil pH over time between the lime materials on the Anselmo, Holdrege, and Hord soils. However, BL did a better job of increasing and maintaining a higher pH than DFA and AGL. Both the Anselmo and Holdrege soils had low initial exchangeable Al compared to the Hord and Valentine soils. McCallister et al. (2002) showed that the exchangeable soil Al in the Anselmo and Hord soils was not significantly reduced after DFA and AGL additions in a laboratory study. Results from the Hord site show that AGL and DFA can significantly reduced percent Al saturation for up to five years after application. Although Mo and Se concentrations in plant tissue was not monitored in this study, past research results and calculated application rates in this study indicate that there is little chance of nutritional toxicities in grazing animals. Results indicate that lime applications could be needed more frequently on the Valentine and Hord soils than on the Anselmo and Holdrege soils. Overall, fly ash is an acceptable alternative liming material when used at the rates tested in this study.
Technical Abstract: Fly ash produced as a by-product of sub-bituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was conducted to determine if fly ash produced from the Nebraska Public Power District Gerald Gentleman Power Station located in Sutherland, NE could be used as an alternative liming material. This study had the following objectives: (i) Compare the effects of fly ash on soil pH with other common agricultural lime materials; (ii) determine the effects of fly ash on percent Al saturation in selected soils; and (iii) determine the effects of fly ash on corn grain yields. Combinations of dry fly ash (DFA), wet fly ash (WFA), beet lime (by-product of sugar beet [Beta vulgaris L.] processing) (BL), and agricultural lime (AGL) were applied at rates ranging from 0.43 to 1.62 times the recommended lime rate to plots on four acidic soils (Anselmo fine sandy loam, Hord fine sandy loam, Holdrege sandy loam, and Valentine fine sand). Soil samples were collected to a depth of 0.2 m from plots and analyzed for pH prior to lime applications and twice periodically after lime application. The Hord and Valentine soils were analyzed for exchangeable Ca, Mg, K, Na, and Al for determination of percent Al saturation on selected treatments and sampling dates. Corn grain yields were determined annually. Depending on the lime source, soil pH increased in the upper 0.2 m of soil the year after application compared to the pre-application soil pH values for some sites and years while in others there were no significant increases in pH. However, all lime materials at each site failed to raise the soil pH in the upper 0.2 m of all the treatments and soil types to the target pH of 6.5. Fly ash and AGL treatments did not significantly increase corn grain yields compared to the control on the Anselmo, Hord, and Holdrege soils. At the Hord site, AGL and DFA significantly reduced percent Al saturation by 3.1 and 3.7% compared to the control five years after application, respectively. Fly ash did not negatively affect corn grain yields compared to AGL. Yields were 12,472, 12,233, and 12,177 kg ha-1 for the Anselmo, Holdrege, and Hord sites averaged over all treatments and years. The lack of yield response to lime additions was potentially a result of lime materials not raising the soil pH to sufficient levels, higher subsoil pH values, or the exchangeable Al not being high enough prior to lime material application to reduce grain yields in these soils. We conclude that the fly ash utilized in this study and applied at rates in this study, increases soil pH comparable to agricultural lime and is an appropriate alternative liming material.