| Amending litter with aluminum sulfate (Al-S) has proven to be effective in reducing water-soluble P but there are concerns that it could result in soil pH reduction and increase levels of extractable soil Al if applied to acidic soils. A glasshouse study with soybean (Glycine max, L Merr) and cotton (Gossypium hirsutum L) as test crops was conducted to determine the impact of applying litter amended with Al-S at 0, 10 and 20% to an acidic sandy loam soil. These treatments were applied to meet N needs of a crop grown in soil with pH levels of 4.5, 5.0, 5.5 and 6.5. The experimental design was a randomized complete block.;Application of BL + 20% Al-S to soil with initial pH of 4.5 or 5.0 significantly decreased the pH compared to BL. The decrease in soil pH with application of BL + 20% Al-S was attributed to high concentrations of geochemically labile Al which released hydrogen ions upon hydrolysis. Both BL and BL + 10% Al-S increased the initial soil pH and decreased extractable soil Al. Application of BL + 20% Al-S resulted in significant higher levels of extractable soil Al than BL and the differences were greater in the lower pH soils. Mehlich-3 extractable soil P, K, Mg, Ca, and Cu decreased with BL + 10 or 20% Al-S relative to BL. Soybean or cotton biomass from BL + 20% Al-S fertilization was significantly decreased relative to BL fertilized soils with initial pH of 4.5 or 5.0. Biomass with BL + 10% Al-S application were not statistically different from those fertilized with BL. Fertilizing cotton or soybean with BL + Al-S decreased tissue Al, N and P concentration. BL and BL + 10% Al-S showed the potential to increase soil pH and reduce extractable soil Al in acid soils but need further field evaluation. |
