The effectiveness of lime, chicken manure and leaf litter ash in ameliorating acidity in a soil previously under black wattle (Acacia mearnsii) plantation

There are about 130,000 hectares of land in South Africa that have been under black wattle plantation for a long time and whose soils have become more acidic than those from contiguous land without the tree. This incubation study investigated the effectiveness of lime, chicken manure and leaf litter ash to ameliorate the soil acidity. Lime and chicken manure were applied in pots at rates equivalent to 0, 5, 10 and 20 Mg ha−1 while ash was applied at 0, 3 and 5 Mg ha−1. In comparison to the control, the application of all the three amendments caused significant increases in soil pHKCL (4.1–5.6) and reduced the exchangeable acidity. The liming effectiveness of the amendments varied with rate and type of amendment and were in the order: lime>chickenmanure>ash. A similar trend was evident in the concentration of exchangeable bases (Ca, Mg and K) in the soil. The effectiveness of ash and chicken manure as liming material was 0.12 and 0.26 respectively compared to lime. The difference in liming effect between ash and chicken manure was related to their alkalinity concentration. It was concluded that both amendments have the potential to be used as liming materials and merit further field evaluation.