Water cost savings from soil biochar amendment: A spatial analysis

Abstract

While a large body of literature exists on the ability of biochar to retain water and nutrients, little research exists connecting these benefits to biochar qualities, water retention mechanisms, and optimal locations for agricultural use. More information is needed for biochar stakeholders to make informed decisions about where deployment should occur. Specifically, we need to know the biochar characteristics that drive changes in soil water properties, how these effects vary geographically, and what financial benefits farmers can expect in their specific region to identify where biochar can be deployed for optimal results. We conducted a meta-analysis of the relationship between biochar properties, application rates and observed change in water holding capacity (WHC) as a function of soil texture. Then we mapped our results across US counties to determine where biochar application could yield the largest improvements in soil water properties and added an economic model designed to predict how biochar-driven changes in soil WHC drive irrigation expenses. Limited data drove our focus to sandy soils, and among these locations, our results suggest that biochar application will be especially effective in the southeast, far north and northeast, and western United States. In a prototype application of our model we predict a 37% reduction in irrigated water use for an instrumented site in Nebraska. Our combined statistical and economic models will be useful for future field experiment proposals, farmers purchasing biochar, and decision makers working to incentivize agricultural advances.