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

Jesmin, Tanjila

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

Description

Title

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

Author(s)

Jesmin, Tanjila

Issue Date

2022-07-15

Director of Research (if dissertation) or Advisor (if thesis)

Mulvaney, Richard L

Doctoral Committee Chair(s)

Arai, Yuji

Committee Member(s)

• Margenot, Andrew J
• Boutton, Thomas W

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

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

Abstract

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.

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Tanjila Jesmin

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