Mineralisation of organic matter in intact versus sieved/refilled soil cores

Stenger, Roland; Barkle, G. F.; Burgess, Craig

doi:10.1071/sr01003

Cited by 21 publications

(15 citation statements)

References 30 publications

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“…Surprisingly, disturbance of the soil resulted both in lower and higher C mineralization rates, while most other studies found higher C mineralization rates after disturbance of the soil (Balesdent et al 2000;Stenger et al 2002). It has to be mentioned that in these experiments reported in literature the soil was disturbed by sieving, which is far more extreme than the disturbance in our experiment and than an intensive tillage operation in the field.…”

Section: Carbon Mineralization Ratecontrasting

confidence: 54%

The effect of reduced tillage agriculture on carbon dynamics in silt loam soils

D’Haene

Sleutel

Neve

et al. 2008

Nutr Cycl Agroecosyst

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Reduced tillage (RT) agriculture is an effective measure to reduce soil loss from soils susceptible to erosion in the short-term and is claimed to increase the soil organic carbon (SOC) stock. The change in distribution and total SOC stock in the 0-60 cm layer, the stratification of microbial biomass carbon (MB-C) content in the 0-40 cm layer and the carbon (C) mineralization in the upper 0-5 cm layer in silt loam soils in Western Europe with different periods of RT agriculture were evaluated. Ten fields at seven locations, representing the important RT types and maintained for a different number of years, and eight fields under conventional tillage (CT) agriculture with similar soil type and crop rotation were selected. RT agriculture resulted in a higher stratification of SOC in the soil profile than CT agriculture. However, the total SOC stock in the 0-60 cm layer was not changed, even after 20 of years RT agriculture. The MB-C was significantly higher in the 0-10 cm layer under RT agriculture, even after only 5 years, compared to CT agriculture. The higher SOC and MB-C content in the upper 0-5 cm layer of RT fields resulted in a higher C mineralization rate in undisturbed soil in the laboratory. Simulating ploughing by disturbing the soil resulted in inconsistent changes (both lower and higher) of C mineralization rates. A crop rotation with root crops, with heavy soil disturbance every 2 or 3 years at harvest, possibly limited the anticipated positive effect of RT agriculture in our research

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Section: Carbon Mineralization Ratecontrasting

confidence: 54%

The effect of reduced tillage agriculture on carbon dynamics in silt loam soils

D’Haene

Sleutel

Neve

et al. 2008

Nutr Cycl Agroecosyst

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“…Including microscale heterogeneities in the kinetics of SOM models is recognized as a much needed advancement in the field (Manzoni and Porporato, 2009;Sierra and Muller, 2015;Wieder et al, 2015), though only a few attempts have been made in this direction (e.g., Ebrahimi and Or, 2016;Van Oijen et al, 2017). In contrast, there are several examples of upscaling schemes for chemical reaction networks (Tang andRiley, 2013, 2017). The challenge is therefore to develop spatially upscaled models that describe SOM decomposition at the macroscale while taking into account the microscale heterogeneities.…”

Section: Introductionmentioning

confidence: 99%

Dynamic upscaling of decomposition kinetics for carbon cycling models

et al. 2020

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Abstract. The distribution of organic substrates and microorganisms in soils is spatially heterogeneous at the microscale. Most soil carbon cycling models do not account for this microscale heterogeneity, which may affect predictions of carbon (C) fluxes and stocks. In this study, we hypothesize that the mean respiration rate R‾ at the soil core scale (i) is affected by the microscale spatial heterogeneity of substrate and microorganisms and (ii) depends upon the degree of this heterogeneity. To theoretically assess the effect of spatial heterogeneities on R‾, we contrast heterogeneous conditions with isolated patches of substrate and microorganisms versus spatially homogeneous conditions equivalent to those assumed in most soil C models. Moreover, we distinguish between biophysical heterogeneity, defined as the nonuniform spatial distribution of substrate and microorganisms, and full heterogeneity, defined as the nonuniform spatial distribution of substrate quality (or accessibility) in addition to biophysical heterogeneity. Four common formulations for decomposition kinetics (linear, multiplicative, Michaelis–Menten, and inverse Michaelis–Menten) are considered in a coupled substrate–microbial biomass model valid at the microscale. We start with a 2-D domain characterized by a heterogeneous substrate distribution and numerically simulate organic matter dynamics in each cell in the domain. To interpret the mean behavior of this spatially explicit system, we propose an analytical scale transition approach in which microscale heterogeneities affect R‾ through the second-order spatial moments (spatial variances and covariances). The model assuming homogeneous conditions was not able to capture the mean behavior of the heterogeneous system because the second-order moments cause R‾ to be higher or lower than in the homogeneous system, depending on the sign of these moments. This effect of spatial heterogeneities appears in the upscaled nonlinear decomposition formulations, whereas the upscaled linear decomposition model deviates from homogeneous conditions only when substrate quality is heterogeneous. Thus, this study highlights the inadequacy of applying at the macroscale the same decomposition formulations valid at the microscale and proposes a scale transition approach as a way forward to capture microscale dynamics in core-scale models.

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“…Sieving of soil might (1) reduce microbial activity because of physical destruction of populations and substrate, or (2) enhance growth of the microbial biomass because of increased resource availability and, thus, also increase N immobilisation. Stenger et al 15. did not observe differences in changes in microbial biomass during the experiment between intact and sieved soil cores.…”

Section: Discussionmentioning

confidence: 85%

“…Whereas Kristensen et al 23. did not find an effect of sieving of the soil on net N mineralisation, Stenger et al 15. reported lower cumulative net N mineralisation of sieved than of intact soil cores.…”

Section: Discussionmentioning

confidence: 92%

“…We did not include Na 2 MoO 4 because it contains oxygen which might interfere with δ 18 O measurements in NO

_{3}^{−}

used for another purpose. To equilibrate the soil matrix potential, we applied a vacuum of 30 kPa for 2 h, which is known to create optimal conditions for (aerobic) microbial activity 15. On the 1st, 3rd, and 7th day after establishing we leached the soil monoliths with 0.1 L of the nutrient solution by applying a vacuum of 30 kPa.…”

Section: Methodsmentioning

confidence: 99%

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Nitrogen‐15 in NO characterises differently reactive soil organic N pools

Oelmann

Wilcke

Bol³

2005

Rapid Comm Mass Spectrometry

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Intercropping with legumes is known to increase the plant-available nitrogen (N) in soil, but can also increase leaching of NO3- to the groundwater. To minimise NO3- leaching risks, knowledge of the N-release processes is essential, including an estimate of the contribution of legumes to total NO3- concentrations in soil. Our objectives were to answer the questions: (1) whether the presence of legume roots increases N mineralisation, and (2) whether the proportion of legume-derived N in NO3- could be calculated with the help of natural abundance 15N in NO3-. We sampled soil monoliths of a Medicago x varia Martyn monoculture in August 2004 and set up three treatments: 'disturbance' (sieved to <2 mm), 'disturbance-roots' (sieved to <2 mm and visible roots removed), and 'control' (left untreated). During an incubation period of 70 days, an N-free nutrient solution was leached through the samples weekly. In the leachates we measured total N, total organic carbon, NO3-, and NH4+ concentrations. Six of the 13 sampling dates were chosen for N isotope analysis in NO3-. Nitrate was separated as AgNO3. During the incubation, 3 to 6% of the initial total mass of total N (192 to 274 mg N) in soil was mineralised. Nitrogen mineralisation followed zero-order kinetics independent of treatments. Mineralisation rates decreased in the order control (day 70: 3.7 microg NO3-N (mg Ninitial)-1)>disturbance-roots (2.6 microg NO3-N (mg Ninitial)-1)>disturbance (1.9 microg NO3-N (mg Ninitial)-1), indicating that mineralisation of legume roots did not play a major role in N mineralisation. The delta15N values jumped from ca. 3 per thousand to ca. 8 per thousand after 2 weeks of incubation, which we attributed to the contribution of two N pools. An exponential two-pool model could not be fitted to the data. Legume-derived soil organic matter, SOM (pool 1), was mineralised at the same rate as SOM accumulated before establishment of the legumes (pool 2). Fresh legume roots did not contribute significantly to N mineralisation.

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Mineralisation of organic matter in intact versus sieved/refilled soil cores

Cited by 21 publications

References 30 publications

The effect of reduced tillage agriculture on carbon dynamics in silt loam soils

The effect of reduced tillage agriculture on carbon dynamics in silt loam soils

Dynamic upscaling of decomposition kinetics for carbon cycling models

Nitrogen‐15 in NO characterises differently reactive soil organic N pools

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