Understanding the impact of residue and nitrogen inputs on soil carbon and nitrogen dynamics

The effect of N fertilization on residue decomposition has been studied extensively; however, contrasting results reflect differences in residue quality, the form of N applied, and the type of soil studied. Two 60-d laboratory incubation experiments were conducted to compare the effect of synthetic N addition (as NH4+ or NO3–) on the decomposition of corn (Zea mays L.) stover, in which (1) a Mollisol was treated with high and low C:N ratio residues; or (2) a single residue was incorporated in two Alfisols of contrasting N supply. In both projects, CO2 emissions were monitored continuously with or without atmospheric 13C analysis and periodic measurement of active biomass, microbial biomass C and N, enzyme activities involved in C (cellulase and β-glucosidase) and N (protease and deaminase) cycling, and gross N mineralization and immobilization by 15N pool dilution. Cumulative CO2 production was greater for the high than low N residue treatment, and was significantly increased by the addition of exogenous N. The stimulatory effect of mineral N was greater for the low- than high-N supplying soil and more prominent in the first than in the second month of incubation, as would be expected due to more rapid substrate depletion from microbial C utilization previously enhanced by greater N availability. The stimulatory effect of exogenous N was verified with respect to microbial indicators, all of which were significantly correlated with cumulative CO2 production. No consistent soil- or treatment-specific differences occurred in measuring gross N mineralization and immobilization; however, net immobilization was usually observed in both studies. Intensive N fertilization in modern corn production increases the input of residues but is not conducive to soil C sequestration.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Jesmin, Tanjila

Contributors dc:contributor

• Mulvaney, Richard L
• Arai, Yuji
• Margenot, Andrew J
• Boutton, Thomas W

• Soil fertility
• C mineralization
• C sequestration
• 13C
• Incubation study
• CO2 production
• Gross N mineralization/immobilization
• Active biomass
• Microbial biomass
• Cellulase
• Protease
• B-glucosidase
• Deaminase
• Residue decomposition
• N fertilization

Statement dc:rights

• Copyright 2022 Tanjila Jesmin

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115948

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115948