Use of Fly Ash as a Liming Material of Corn and Soybean Production on an Acidic Sandy Soil

Fly ash (FA) produced from subbituminous coal combustion can potentially serve as a lime material for crop production in acidic soils. A five-year study was conducted to determine if FA was an effective liming material in an acid sandy soil under corn and soybean grain production. Fly ash and pelletized lime (PL) were surface applied at rates ranging from 3,200 to 6,400 and 1,416 to 5,658 kg/ha (0.5 to 2 times the recommended rate) at two sites near Brunswick, NE, respectively. At Site A, lime source additions increased soil pH by 0.7 units and decreased soil exchangeable Al by 7.3 mg/kg to a depth of 20 cm. Lime applications resulted in pH increase during the first year (2004) at the 0 to 10-cm depth, and in 2007 at the 10 to 20-cm depth. At Site B, soil pH data suggested that one or more past lime applications may have occurred. Corn and soybean grain yields were not different during each year between the control and lime source treatments at both sites. This lack of difference was likely due to soluble Al concentrations not being great enough to affect grain yield. Fly ash did not negatively affect grain yields in this study. Boron concentration (400 mg/kg) in FA were likely too low to adversely affect yields. The FA applied at rates in this study, increased pH comparable to PL and is an appropriate liming material.