Pine chip and poultry litter derived biochars affect C and N dynamics in two Georgia, USA, Ultisols

Authors: Weyers, Sharon; DAS, KESHAV - UNIVERSITY OF GEORGIA; GASKIN, JULIA - UNIVERSITY OF GEORGIA; LIESCH, AMANDA - UNIVERSITY OF FLORIDA

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2023
Publication Date: 2/12/2023
Citation: Weyers, S.L., Das, K.C., Gaskin, J.W., Liesch, A.M. 2023. Pine chip and poultry litter derived biochars affect C and N dynamics in two Georgia, USA, Ultisols. Agronomy. 13(2). Article 531. https://doi.org/10.3390/agronomy13020531.
DOI: https://doi.org/10.3390/agronomy13020531

Interpretive Summary: Biochar made from high temperature, low oxygen combustion of plant or waste materials may have environmental benefits when applied to the soil. Researchers from the ARS in Morris, MN, and the University of Georgia conducted short-term laboratory incubations to evaluate prospects of carbon sequestration and nutrient delivery from addition of a poultry litter-based or pine chip-based biochars to two Georgia soils. Application of poultry litter biochar increased soil carbon content and nitrogen availability in both Cecil and Tifton soils. Application of pine chip biochar had no effect on microbial processes in Tifton soil so would be a good candidate for carbon sequestration. However, application of pine chip biochar resulted in short-term carbon loss, but increased nitrogen availability. Selective addition of either of these biochars to field soils will likely improve soil quality by increasing long-term soil carbon content and improving nutrient cycling processes. Scientists, land managers, and policy makers will benefit from this applying this research to develop recommendations for achieving environmental benefits from biochar land application.

Technical Abstract: Some biochars produced by pyrolysis of biomass have the potential to sequester C and enhance nutrient supplies in agricultural soils. A 28-day lab incubation was used to assess the potential effects of biochars derived from pine chips (PC) or poultry litter (PL) applied at five application rates (0, 22.5, 45.0, 67.5, and 90 Mg ha-1 equivalent). Biochars were applied to two acidic Ultisols, a Cecil sandy loam and a Tifton loamy sand, found in Georgia, USA. Cumulative basal soil respiration was measured over the 28-day incubation. Other soil properties measured before and after incubation were soil pH, total soil organic carbon (SOC), total soil N, soluble organic C (OC), soil mineral nitrogen (NH4+-N and NO3--N), and microbial biomass C (MBC). Before incubation, addition of both PC and PL biochars increased soil pH, total SOC, and C:N ratio in both soils. Addition of the PL biochar increased total soil N, soluble OC, and NO3--N in both soils, MBC in Tifton soil, and NH4+-N in Cecil soil. Addition of the PC biochar decreased NO3--N in Cecil soil but increased it in Tifton soil. After the 28-day incubation, averaged across soils, pH increased in the 22.5 Mg ha-1 PC and 22.5 and 67.5 Mg ha-1 PL treatments, total SOC declined in the 45 and 67.5 Mg ha-1 PC treatments, and the C:N increased in soil controls and decreased in the 67.5 Mg ha-1 PC treatment. In Cecil soil, the MBC declined in PL treatments except at 90 Mg ha-1, and NH4+-N declined in the 90 Mg ha-1 PC treatments. In Tifton soil, MBC increased in the 45 Mg ha-1 PL treatment, and NH4+-N increased in all but the 22.5 Mg ha-1 PL treatments. Total N and NO3--N did not change with incubation. Basal respiration was not affected by biochar, though it was generally greater in Cecil than Tifton soil. Net SOC loss and the initial increase in soluble OC and MBC indicated potential C priming from adding both biochars. Increased NH4+-N with time in Tifton PL treatments indicated potential N priming. In Cecil soil, the PC biochar may have immobilized NH4+-N, but PL biochar likely supplied it. In Tifton soil, PC biochar appeared to be generally inert, but PL biochar supplied soluble OC and NH4+-N, although it might have inhibited nitrification.