Effects of Elevated CO2 in the Atmosphere on Soil C and N Turnover

The importance of labile soil carbon (C) and nitrogen (N) in soil biogeochemical processes is now well recognized. However, the quantification of labile soil C and N in soils and the assessment of their contribution to ecosystem C and N budgets is often constrained by limited information on spatial variability. To address this, we examined spatial variability in dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) in a Sitka spruce forest in central Ireland. The results showed moderate variations in the concentrations of DOC and DTN based on the mean, minimum, and maximum, as well as the coefficients of variation. Residual values of DOC and DTN were shown to have moderate spatial autocorrelations, and the nugget sill ratios were 0.09% and 0.10%, respectively. Distribution maps revealed that both DOC and DTN concentrations in the study area decreased from the southeast. The variability of both DOC and DTN increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. The cokriging technique performed better than the ordinary kriging for predictions of DOC and DTN, which are highly correlated. This study provides a statistically based assessment of spatial variations in DOC and DTN and identifies the sampling effort required for their accurate quantification, leading to improved assessments of forest ecosystem C and N budgets.

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Impacts of irrigation on soil C and N stocks in grazed grasslands depends on aridity and irrigation duration

Geoderma ◽

10.1016/j.geoderma.2021.115109 ◽

2021 ◽

Vol 399 ◽

pp. 115109

Author(s):

Paul L. Mudge ◽

Jamie Millar ◽

Jack Pronger ◽

Alesha Roulston ◽

Veronica Penny ◽

...

Keyword(s):

Soil C ◽

Soil C And N ◽

C And N

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C and N urban soil budget and its spatial differentiation in comparison with natural areas in the Wroclaw region of Poland

E3S Web of Conferences ◽

10.1051/e3sconf/20184500085 ◽

2018 ◽

Vol 45 ◽

pp. 00085

Author(s):

Izabela Sówka ◽

Yaroslav Bezyk ◽

Maxim Dorodnikov

Keyword(s):

Urban Soil ◽

Spatial Differentiation ◽

Clay Content ◽

Dry Mass ◽

Microbial Biomass C ◽

Natural Areas ◽

Soil C ◽

Soil C And N ◽

C And N ◽

Natural Grassland

An assessment of C and N balance in urban soil compared to the natural environment was carried out to evaluate the influence of biological processes along with human-induced forcing. Soil C and N stocks were quantified on the samples (n=18) collected at 5 - 10 cm depth from dominated green areas and arable lands in the city of Wroclaw (Poland) and the relatively natural grassland located ca. 36 km south-west. Higher soil carbon and nitrogen levels (C/N ratio = 11.8) and greater microbial biomass C and N values (MBC = 95.3, MBN = 14.4 mg N kg-1) were measured in natural grassland compared with the citywide lawn sites (C/N ratio = 15.17, MBC = 84.3 mg C kg-1, MBN = 11.9 mg N kg-1), respectively. In contrast to the natural areas, the higher C and N concentration was measured in urban grass dominated soils (C = 2.7 % and N = 0.18 % of dry mass), which can be explained mainly due to the high soil bulk density and water holding capacity (13.8 % clay content). The limited availability of soil C and N content was seen under the arable soil (C = 1.23 %, N = 0.13 %) than in the studied grasslands. In fact, the significantly increased C/N ratios in urban grasslands are largely associated with land conversion and demonstrate that urban soils have the potential to be an important reservoir of C.

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Simulation of protozoa-induced mineralization of bacterial carbon and nitrogen

Canadian Journal of Soil Science ◽

10.4141/cjss92-020 ◽

1992 ◽

Vol 72 (3) ◽

pp. 201-216 ◽

Cited By ~ 17

Author(s):

P. M. Rutherford ◽

N. G. Juma

Keyword(s):

N Mineralization ◽

Ecological Research ◽

Clay Loam ◽

Glucose Addition ◽

Soil C ◽

Carbon And Nitrogen ◽

Soil C And N ◽

C And N ◽

Typic Cryoboroll ◽

Bacterial C

Modelling in soil ecological research is a means of linking the dynamics of microbial and faunal populations to soil processes. The objectives of this study were (i) to simulate bacterial-protozoan interactions and flows of C and N in clay loam Orthic Black Chernozemic soil under laboratory condtions; and (ii) to quantify the flux of C and N (inputs and outputs) through various pools using the simulation model. The unique features of this model are: (i) it combines the food chain with specific soil C and N pools, and (ii) it simultaneously traces the flows of C, 14C, N and 15N. It was possible to produce a model that fitted the data observed for the soil. The simulated CO2-C evolved during the first 12 d was due mainly to glucose addition (171 μg C g−1 soil) and cycling of C in the soil (160 μg C g−1 soil). During this interval, bacterial C uptake was 5.5-fold greater than the initial bacterial C pool size. In the first 12 d protozoa directly increased total CO2-C evolution by 11% and increased NH4-N mineralization 3-fold, compared to soil containing only bacteria. Mineralization of C and N was rapid when bacterial numbers were increased as a result of glucose addition. Key words: Acanthamoeba sp., modelling, N mineralization-immobilization, organic matter, Pseudomonas sp., Typic Cryoboroll

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