Calcium sulfate or coal combustion by-product spread on the soil surface to reduce evaporation, mitigate subsoil acidity and improve plant growth

• Published in: Plant and soil 1996-05, Vol.182 (2), p.209-219
• Main Authors: Ritchey, K.D., Korcak, R.F., Feldhake, C.M., Baligar, V.C., Clark, R.B.
• Format: Article
• Language: English
• Subjects: Acid soils; Acid sulfate soils; Calcium sulfate; Clay soils; Fluidized bed combustion; Gypsiferous soils; Leaching; Orchard soils; Soil depth; Soil water; Sorghum bicolor
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF00029052

Removal of sulfur dioxide from flue gas produced by coal-burning power plants has increased the availability of by-products that may be useful as soil amendments for agriculture. We studied the effects of surface layers (caps) of fluidized bed combustion residue-fly ash mixture (FBCR-FA) or calcium sulfate on reduction of evaporative water losses and improvements in subsurface acid soil chemical characteristics. Caps 3.8 cm thick of porous FBCR-FA, hydrated commercial calcium sulfate (CCS), or soil (check) were placed on columns of coarse-loamy, mixed, mesic Umbric Dystrochrept soil of pH 4.2. After the addition of 40 cm of water during a 16-week period, mean daily water loss from the column with the FBCR-FA cap was 0.51 mm compared to 0.98 mm in the check. Mean increase in soil exchangeable Ca in the 5- to 40-cm depth for the CCS treatment was 0.83 cmolc kg⁻¹ and mean pH (H₂O) increase was 0.21 units. Mean KCl-extractable Al decreased from 6.08 to 5.52 cmolc kg⁻¹. Roots of sudangrass (Sorghum bicolor (L.) Moench) planted in the columns after removal of the caps reached 2 cm depth in the control, 18 cm in the FBCR-FA and 38 cm in the CCS treated columns after 47 days of growth. The gypsum cap was effective in improving deep rooting in acid soils and the FBCR-FA cap reduced evaporative water losses.