Does biochar conserve soil and water?

Conserving soil and water under frequent droughts, heat waves, and other extreme weather events is a growing global challenge (Schlaepfer et al. 2017; Moravec et al. 2021). Indeed, soil erosion continues to be one of the major agents of soil degradation globally. For example, in the US Midwest, soil thickness on summit landscape positions has decreased by 1.8 ± 1.2 mm y⁻¹ (0.07 ± 0.05 in yr⁻¹) during the past 150 years according to surveys (Thaler et al. 2022). This reduction in soil thickness is equivalent to about 22.5 ± 15 Mg ha⁻¹ y⁻¹ (10.0 ± 6.7 tn ac⁻¹ yr⁻¹) of soil loss, which is almost twice the tolerable level (11 Mg ha⁻¹ y⁻¹ [4.9 tn ac⁻¹ yr⁻¹]) of soil loss for this region. Rates of soil erosion can be even greater in other regions of the globe with degraded soils. For instance, in some regions of Africa, rates of soil erosion from croplands are as high as 300 Mg ha⁻¹ y⁻¹ (133.8 tn ac⁻¹ yr⁻¹) (Vagen et al. 2005). Despite decades of advocating the importance of conservation practices, soil erosion remains a major global challenge. Improving soil resistance against erosion or reducing soil erodibility (soil susceptibility to erosion) through conservation practices is a priority to maintain soil productivity, reduce soil C loss, and maintain other soil ecosystem services.

Additionally, droughts are another challenge on a global scale (Schlaepfer et al. 2017; Moravec et al. 2021). Some regions of the globe are shifting toward a drier climate due to erratic precipitation (Schlaepfer et al. 2017). Even moderate drought events can …