Chemical Response of Soils to Traditional and Industrial Byproduct Wood Biochars

Abstract

ABSTRACT Soil degradation and a global focus on carbon (C) sequestration in soils have resulted in growing societal interest in soil health practices. Biochar has a high C content, porosity, pH, and cation exchange capacity that benefit soil properties. Here we described an incubation study that aims to evaluate the influences of biochar additions on representative forest organic, forest mineral, blueberry, potato, and mixed vegetable soils from Maine, USA. The experiment consisted of amendments of either a lime stabilized industrial byproduct softwood pulp biochar (SPB) or pine wood biochar (PB) at application rates equivalent to 0, 5, 10, 25, 50, and 100 t ha−1. Here we report influences of biochar addition on soil pH, loss-on-ignition (LOI), water-holding capacity (WHC), and exchangeable cations. In general, both SPB and PB increased the value of these soil properties in all mineral soils, with significant increases often being found at a rate of 100 t ha−1. Forest organic soils, however, were more variable attributable to the high organic C concentration of this substrate. Soil response to SPB amendments was strongly influenced by the lime component, although few significant differences were found between SPB and PB amended soils. Analysis of carbon dioxide (CO2) emissions from SPB amendments due to lime dissolution and acid neutralization represented less than 3% of the total carbon added in SPB treated soils, leaving SPB and PB both important potential soil amendments. This suggests that both traditional and industrial byproduct biochars have potential for soil health and C sequestration management goals.