Impact of Biochar Treatment on Chemical Properties of a Sandy Spodosol Developed from Marine Sediments.

An experiment using leaching columns was conducted for 72 weeks to determine the impact of biochar treatment on a sandy Spodosol. Biochar treatment was found to have a positive impact on soil chemical properties. The treated topsoil had higher exchangeable K, Ca and Mg compared to the control. Due to low clay and organic matter content, much of the cations released by biochar could not be retained in that zone. This is evidenced by the increased concentration of elements in leachates collected from the leaching columns. It means that a significant portion of the nutrients, initially in insoluble form, was susceptible to leaching or podzolization. Some of the nutrients were transported downwards and subsequently retained in the spodic horizon. The biochar treatment increased soil pH, total C and the CEC of the spodic layer with the CEC increase being positively correlated with C content. Notwithstanding, the ameliorative impact of biochar treatment is at best short-term. The application of high amounts of biochar is necessary to raise soil fertility to the level suitable for crop production. Hence, it is recommended that biochar be applied in combination with some NPK fertilizers to sustain crop growth/production in the long term. [ABSTRACT FROM AUTHOR]