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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #393207
Research Project: Innovative Manure Treatment Technologies and Enhanced Soil Health for Agricultural Systems of the Southeastern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Mineral N suppressed priming effect while increasing microbial C use efficiency and N2O production in sandy soils under long-term conservation management

Author
item PARAJULI, BINAYA - Clemson University
item YE, RONGZHONG - Clemson University
item Szogi, Ariel

Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2022
Publication Date: 9/16/2022
Citation: Parajuli, B., Ye, R., Szogi, A.A. 2022. Mineral N suppressed priming effect while increasing microbial C use efficiency and N2O production in sandy soils under long-term conservation management. Biology and Fertility of Soils. https://doi.org/10.1007/s00374-022-01665-6.
DOI: https://doi.org/10.1007/s00374-022-01665-6

Interpretive Summary: Restoring soil organic carbon (SOC) with residue incorporation is an important component of soil health management. Soil priming is considered a key component of global carbon (C) cycling, and a significant factor determining the capacity of soils to function as sources or sinks of atmospheric carbon dioxide (CO2). Soil priming is the change in the microbial decomposition of soil organic carbon (SOC) in response to fresh C inputs. Therefore, we investigated the interactive effect of residue amendment and mineral nitrogen (N) additions on preserving the added residues and SOC in sandy soils of the Southern Coastal Plain. Soil samples were collected from fields under long-term reduced tillage and incubated with either carbon-labeled crop residues, ammonium nitrate (NH4NO3), both, or neither for 55 days. During the incubation we measured microbial respiration, C biomass, enzyme activities, C use efficiency (CUE), and nitrous oxide (N2O) production (a potent greenhouse gas). Our results showed that the residue amendment stimulated enzyme activities inducing positive priming effect. The mineral N addition reduced priming effects of residue amendment while increasing microbial C use efficiency. The mineral N addition reduced the decomposition of the added residues and augmented the positive impacts of residue amendment on N2O production. These results reinforced the concept that N can regulate SOC dynamics through direct and indirect impacts on soil microbial communities. Combining N fertilization and residue management is seemingly promising to increase SOC stability and preservation in sandy soils. However, the trade-offs of N2O production need to be considered

Technical Abstract: Restoring soil organic carbon (SOC) with residue incorporation is an important component of soil health management. In the present study, we investigated the interactive impacts of residue amendment and mineral nitrogen (N) additions on preserving the added residues and SOC in a sandy Ultisols. Soil samples were collected from fields under long-term reduced tillage and incubated with either carbon-labeled crop residues (13C), ammonium nitrate (NH4NO3), both, or neither for 55 days. Microbial respiration, biomass carbon (C), enzyme activities, and carbon use efficiency (CUE) were measured along with nitrous oxide (N2O) production. Residue amendment increased carbon dioxide (CO2) production by 206% at the end of the incubation, inducing positive priming effects (PE). Mineral N reduced the positive impacts of residue amendment on CO2 production and PE, resulting in higher microbial CUE. However, N addition had no effects on the measured C-cycling enzymes, except for '-glucosidase when residues were present. Additions of mineral N reduced residue decomposition by 89% at the end of the experiment. Total CO2 (R2= -0.56), residue-derived CO2 (R2= -0.62), SOC-derived CO2 (R2= -0.53), and the primed production (R2= -0.52) were all negatively correlated to soil NH4+ concentrations. Residue amendment instantly stimulated N2O production, which was augmented by mineral N addition. Denitrification was seemingly the main N2O production pathway. The results reinforced the concept that N can regulate SOC dynamics through direct and indirect impacts on soil microbial communities. Combining N fertilization and residue management is seemingly promising to increase SOC stability and preservation in sandy soils. However, the trade-offs of N2O production need to be considered.