Boron Release from Fly Ash and its Uptake by Corn

Abstract

Abstract The increasing costs of disposing of fly ash create an urgent need to find potential uses, one of which is land application to improve physical or chemical properties of soils. Because fly ash contains considerable amounts of B, which is often deficient in Southeastern soils, B release from fly ash and its uptake by corn ( Zea mays L. ) were investigated initially under greenhouse conditions. Two fly ashes from Georgia were tested as a source of B for corn grown on two soils of different texture (Cecil: clayey, kaolinitic, thermic Typic Kanhapludult, and Lakeland: thermic, coated Typic Quartzipsamment). Fresh (unweathered) fly ash was applied to Cecil soil at rates equal to 0.0, 3.1, 6.3, 12.5, 25, 50, and 100 g kg −1 soil, while the Lakeland soil being sandier received one‐half of these rates. Hot water extractable B content of fly ash increased with decreasing pH and both soils showed a linear relationship between fly ash rate and hot water extractable soil B. Soil pH was the main factor influencing B release from fly ash in soil‐fly ash systems (at given fly ash rate). Increased rates of B application in fly ash resulted in much higher tissue B contents and caused marked reductions in growth on both soils. Tissue B contents on the sandy Lakeland soil were higher at the same ash rate than on the heavier Cecil soil. Hot water extractable soil B is a good diagnostic criterion for evaluation of B availability to plants on fly ash amended soils.