2026-09-22T06:43:16Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/115948 2023-07-11 col_2142_5131 col_2142_14737 com_2142_5130 com_2142_690 com_2142_397

application/pdf en text Mulvaney, Richard L Arai, Yuji Margenot, Andrew J Boutton, Thomas W 2022-08 Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01 The student, Tanjila Jesmin, accepted the attached license on 2022-07-15 at 15:42. The student, Tanjila Jesmin, submitted this Dissertation for approval on 2022-07-15 at 15:52. This Dissertation was approved for publication on 2022-07-15 at 17:02. DSpace SAF Submission Ingestion Package generated from Vireo submission #18344 on 2022-11-16 at 10:56:30 Understanding the impact of residue and nitrogen inputs on soil carbon and nitrogen dynamics Jesmin, Tanjila 2022-07-15 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 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. Thesis eng https://hdl.handle.net/2142/115948 Copyright 2022 Tanjila Jesmin Ph.D. Dissertation Natural Res & Env Sciences University of Illinois at Urbana-Champaign Natural Res & Env Sci