Abstract

The use of biochar in agricultural soils appears to be promising because it is known to improve soil properties and increase crop production. However, few studies have been conducted with biochar on volcanic soils. Two field experiments were conducted simultaneously to evaluate the effect of oat hull biochar (OBC) on various physical-chemical properties of two volcanic soils, an ‘Inceptisol’ and an ‘Ultisol’, and to evaluate the resulting effects on the yields of barley (Hordeum vulgare) grown on these soils. The OBC doses applied to field microplots were equivalent to 0, 5, 10 and 20 Mg ha-1. The results showed that pH, total exchangeable bases, and electrical conductivity increased at the highest dose of OBC in both soils. Glomalin-related soil protein (GRSP) was significantly high in the Ultisol at a rate of 20 Mg OBC ha-1. Water-stable aggregates (WSA) and mean weight diameter (MWD) were enhanced at the highest doses of OBC in both soils. However, water-holding capacity (WHC) only increased in the Ultisol when amended with OBC at rates of 10 and 20 Mg ha-1. Barley yield (grain weight m-2) significantly increased at the highest OBC dose by 31.3% and 21.9% for crops grown on the Inceptisol and Ultisol, respectively. Significant relationships were observed between WHC and glomalin fractions (r = 0.81, p < 0.01 for easily extractable-GRSP and r = 0.62, p < 0.01 for Total-GRSP) as well as between organic C and WSA and both glomalin fractions. According to this study, biochar may be used effectively to improve the quality of these two volcanic soils and promote sustainable grain production.