A body of emerging research shows the promise of charcoal soil amendments (“biochars”) in restoring fertility in degraded agricultural and forest soils. “Sustainable biochars” derived from locally produced waste biomass and produced near the application site are of particular interest. We tested the effects of surface applications of wood-derived biochars (applied at 7.5 t·ha−1) on soil physiochemical properties (N, P, K, pH, soil moisture content, organic matter content, and bulk density) in three land-use types: agriculture (Camellia sinensis monoculture), agroforestry (C. sinensis with shade trees), and secondary forest (Dipterocarpus dominated) assessed over seven months. We found significant positive effects of biochar on soil physiochemical properties in all land-use types, with the strongest responses in the most degraded tea monoculture sites. Although biochar had no significant effect on soil N and K, it improved soil P—the primary nutrient most commonly limiting in tropical soils. Biochar also enhanced soil moisture and organic matter content, reduced bulk density, and increased soil pH in monoculture sites. Our results support the general hypothesis that biochar can improve the fertility of degraded soils in agricultural and forest systems in Bangladesh and suggest that biochar additions may be of great benefit to the most degraded soils.
Biochar Effects on Soil Physiochemical Properties in Degraded Managed Ecosystems in Northeastern Bangladesh
