A Comparison of Variable Economic Costs Associated with Two Proposed Biochar Application Methods

The addition of biochar to agricultural soils has been shown to improve crop productivity and sequester carbon in soils over a millennial timeline. However, little formal research has assessed the logistics or economics of transitioning to a biochar economy. This paper examines the problem of biochar application to soil. Specifically, we look at two methods of application-broadcast-and-disk and trench-and-fill and provide cost estimates for each under varying rates of saturation. Our findings show that the broadcast process is generally cheaper; however, we consider a trench-and-fill method to be more suitable for storing large quantities of biochar in soil. For broadcast application, we found that at saturation rates of 2.5, 5, 10, 25, and 50 tons per acre, a respective cost per acre is $29, $44, $72, $158, and $300. Our examination of the trench-and-fill process revealed that cost depended on several variables, including saturation rate, trench depth, and operator efficiency. We found that at saturation rates of 5, 10, 25, 50, and 75 tons per acre, with trenches 2 feet deep, and at trenching and application rates of 15 feet per minute, a respective cost per acre of applied biochar is $34, $85, $171, $341, and $512. In both methods, we found results that suggest biochar application could constitute a considerable cost, many times greater than typical agricultural processes. Although our findings offer only a basic guide to calculating the cost of * Corresponding author: Phone 970-618-5005, e-mail: [email protected]. application, the intent of this paper is to serve as a launching pad for the much-needed additional research into the costs and other potential constraints of biochar application to agricultural soils.