Peanut residues supply minimal plant-available nitrogen on a major soil series in the USA peanut basin

Authors: JANI, ARUN - University Of Florida; MULVANEY, MICHAEL - University Of Florida; Balkcom, Kipling; WOOD, C. WESLEY - University Of Florida; JORDAN, DAVID - North Carolina State University; WOOD, BRENDA - Pensacola State College; DEVKOTA, PRATAP - University Of Florida

Submitted to: Soil Use and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2019
Publication Date: 11/27/2019
Citation: Jani, A.D., Mulvaney, M.J., Balkcom, K.S., Wood, C., Jordan, D.L., Wood, B.H., Devkota, P. 2019. Peanut residues supply minimal plant-available nitrogen on a major soil series in the USA peanut basin. Soil Use and Management. 36:274-284. https://doi.org/10.1111/sum.12563.
DOI: https://doi.org/10.1111/sum.12563

Interpretive Summary: Field observations have shown that a substantial portion of peanut leaves separate from stems during pod curing, leading to an uneven distribution of leaves and stems following peanut. Possible differences in nitrogen (N) mineralization rates between peanut leaf and stem residues may lead to variability of available N for subsequent crops. University of Florida and North Carolina State researchers in conjunction with an ARS scientist in Auburn, AL conducted an experiment to to quantify N mineralization in soil amended with different peanut residue components under simulated conventional and conservation tillage. A 252-day microlysimeter incubation was conducted in which peanut leaves, stems, and a 1:1 mixture of leaves:stems from three varieties were incorporated or placed on the soil surface to simulate conventional or conservation tillage, respectively. Soils were periodically leached to assess N mineralization compared to a soil-only control. Over the duration of the incubation, peanut leaves supplied only 25 kg N ha-1 at the 0-15 cm depth, which would likely not produce a yield response for a subsequent crop. These results confirm previous reports that peanut residue N contributions to subsequent crop are minimal across the southeastern USA.

Technical Abstract: Field observations have shown that a substantial portion of peanut leaves abscise in windrows during pod curing, leading to an uneven distribution of leaves and stems when residues are spread during harvest. Possible differences in nitrogen (N) mineralization rates between peanut leaf and stem residues may lead to spatial and temporal variability in available N during subsequent crops. The objective of this study was to quantify N mineralization in soil amended with different peanut residue components under simulated conventional and conservation tillage practices. A 252-day microlysimeter incubation was conducted in which peanut leaves, stems, and a 1:1 mixture of leaves:stems from three varieties were incorporated or placed on the soil surface to simulate conventional or conservation tillage, respectively. Soils were periodically leached to assess N mineralization compared to a soil-only control. Nitrogen mineralization was driven solely by residue component. Soil amended with leaves mineralized 10% more N relative to the control or soil containing stems. On a mass basis, it was estimated that leaves supplied 25 kg N ha-1 over 252 days at 0-15 cm soil depth, which would likely be insufficient to induce a yield response by a subsequent crop. This study suggests that uneven distribution of peanut leaf and stem residues following harvest causes only minor spatial and temporal variability in available N during subsequent crop growth. Additionally, these results support the growing body of evidence indicating that peanut residue N contributions to subsequent crops are negligible in the peanut basin of the southeastern USA.