Effect of paper mill lime sludge as an acid soil amendment

The possibility of using paper mill lime sludge as a soil amendment in an acid soil was investigated. Sludge used contained 58.4% calcium carbonates plus a small amount of heavy metals. A pot experiment was conducted with an acid soil and Sorghum vulgaris variety speed seed as test plant. Treatments with three replicates consisted of 0, 0.5 and 1, 2 and 4% paper mill lime sludge (L0, L0.5, L1, L2 and L4, respectively). Shoot were harvested after 60 days and dry matter yield was determined after drying of the harvested shoots at 70°C for 48h. Subsamples of dry shoots were ground and then dryashed in a furnace at 550°C and then extracted with 2N HCl. The concentrations of P, K, Fe, Mn and Zn were measured in the extracts. Results showed that paper mill sludge significantly increased pH, which was proportional to the application rate of paper mill sludge. The application of 2% sludge (based on soil dry mass) remarkably increased shoot dry matter and P, K, Fe, Mn, K and P uptake.