Location: Soil, Water & Air Resources Research
Project Number: 5030-12210-004-005-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Feb 1, 2026
End Date: Jan 31, 2030
Objective:
Objective 1: Determine the mechanisms by which biochar influences the cycling and
stabilization of manure C in soil environments.
Objective 2: Evaluate the mixing of swine manure with biochar for (a) its impact on soil health and environmental performance, and (b) the effects of mixing time between biochar and manure before land application on its field efficacy.
Objective 3: Develop specific management recommendations as to whether swine manure and biochar should be mixed and/or incubated before land application.
Objective 4: Transfer our findings on the efficacy of mixing biochar and manure through workshops, meetings, and podcasts targeted to key stakeholders, including livestock and crop producers and regulators.
ARS will contribute to Objectives 1 and 2.
Approach:
The overall project will evaluate the potential of pine vs corn stover biochars to reduce nutrient losses and increase carbon stability of swine manure applied to agricultural soils. Cooperators will field-apply the biochars via either a pre-incubated mixture together with manure or instead a separate field application near the time of manure application. Cooperators will subsequently perform all field activities and modeling of results. ARS will collect soil samples at the beginning of the three-year field study and again after the three years. Accumulation of new carbon in the three-year soil samples will
be determined for each field treatment first by separating its soil into larger (more labile) vs smaller (less labile) aggregate size classes, followed by extraction of each aggregate size class for multiple fractions of soil organic matter that differ in their cycling rates-particulate organic matter, two humic acid fractions extracted by alkali, and the unextractable humin. Each organic matter fraction will be analyzed for monomers of carbohydrates, amino compounds, phenols, and fatty acids. Some of these compounds serve as biomarkers, as they can identify whether newly sequestered carbon was derived from either
the biochar, manure, or microbial processing of these amendments. Results will describe the relative efficacy of each manure-biochar treatment to promote soil carbon stability within the three-year span of the proposed field research. This detailed soil fractionation and biochemical analyses will also be performed on the initial soil sample set to confirm the value of this complex approach to study soil organic matter cycling and sequestration.