8. Efficacy of Corncob and Rice Husk Biochar as Liming Agent and Phosphorus Source for Growth of Soybean in Two Acid Soils
Abstract
Soil acidity, unavailability and high cost of conventional liming materials are major constraints to soybean production in the Western Region of Ghana. Research has shown that biochar produced from agricultural waste has high concentration of basic cations and available P that could be exploited for use as liming material and/or P source. However, the biochar type that will provide an ideal soil pH and P availability for soybean production in acid soils has received little attention. Therefore, for this study, two acid soils namely; Ankasa Series (Typic Hapludox) and Tikobo Series (Typic Hapludult) were amended with corncob and rice husk biochar types charred at 500 and 700 oC at a rate of 80 tons/ha in a pot experiment in a screen house to ascertain the efficacy of the biochar types as agricultural lime and P sources for soybean growth. The Ca equivalent of the biochar types from CaCO3 was amended to the soils to serve as realistic control. The soils were arranged in a completely randomized design in a screen house to allow for pH equilibration. After pH equilibration, inoculated soybean seeds were sown at stake. Nitrogen was applied at rates of 0 kg/ha and 10 kg/ha. Phosphorus from TSP was applied at 0 and biochar P equivalent to the non-biochar-amended soils. Extra 30 kg P/ha from TSP was applied to some of the biochar amended soils to ascertain if any, the combined effect of synthetic and biochar P on soybean growth. At flower initiation, the crops were harvested, root volume and P uptake determined. Amended with rice husk biochar charred at 700 oC, the shoot P uptake was 1.3 times more in both the Typic Hapludox and the Typic Hapludult than the same soils amended with conventional lime with equivalent biochar P from the synthetic source.
