Fate of rice shoot and root residues, rhizodeposits, and microbe-assimilated carbon in paddy soil: I. Decomposition and priming effect

Mapping Intimacies ◽

10.5194/bg-2016-86 ◽

2016 ◽

Cited By ~ 1

Author(s):

Zhenke Zhu ◽

Guanjun Zeng ◽

Tida Ge ◽

Yajun Hu ◽

Chengli Tong ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Priming Effect ◽

Paddy Soils ◽

Ch4 Emission ◽

Untreated Soil ◽

Organic C ◽

Soil C ◽

Rice Roots ◽

Native Soil

Abstract. The input of recently photosynthesized C has significant implications on soil organic carbon sequestration, and in paddy soils, both plants and soil microbes contribute to the overall C input. In the present study, we investigated the fate and priming effect of organic C from different sources by conducting a 300-d incubation study with four different 13C-labelled substrates: rice shoots (Shoot-C), rice roots (Root-C), rice rhizodeposits (Rhizo-C), and microbe-assimilated C (Micro-C). The efflux of both 13CO2 and 13CH4 indicated that the mineralization of C in Shoot-C-, Root-C-, Rhizo-C-, and Micro-C-treated soils rapidly increased at the beginning of the incubation and then decreased gradually afterwards. In addition, the highest level of C mineralization was observed in Root-C-treated soil (45.4 %), followed by Shoot-C- (31.9 %), Rhizo-C- (7.9 %), and Micro-C-treated (7.7 %) soils, which corresponded with mean residence times of 33.4, 46.1, 62.9, and 192 d, respectively. Furthermore, the cumulative mineralization of native soil organic carbon in Shoot-C-treated soils was 1.48- fold higher than in untreated soils, and the priming effect of Shoot-C on CO2 and CH4 emission was strongly positive over the entire incubation. However, Root-C failed to exhibit a significant priming effect, which suggests that it could potentially be used to mitigate CH4 emission. Although the total C contents of Rhizo-C- (1.89 %) and Micro-C-treated soils (1.9 %) were higher than those of untreated soil (1.8 %), no significant differences in total C emissions were observed. However, the 13C emissions of Rhizo-C- and Micro-C-treated soils gradually increased over the entire incubation period, which indicated that soil organic C-derived emissions were lower in Rhizo-C- and Micro-C-treated soils than in untreated soil, and that rhizodeposits and microbe-assimilated C could be used to reduce the mineralization of native soil organic carbon and to effectively improve soil C sequestration. The contrasting behaviours of the different photosynthesized C substrates suggests that recycling rice roots in paddies is more beneficial than recycling shoots and reveals the importance of increasing rhizodeposits and microbe-assimilated C in paddy soils via nutrient management.

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Fate of rice shoot and root residues, rhizodeposits, and microbe-assimilated carbon in paddy soil – Part 1: Decomposition and priming effect

Biogeosciences ◽

10.5194/bg-13-4481-2016 ◽

2016 ◽

Vol 13 (15) ◽

pp. 4481-4489 ◽

Cited By ~ 31

Author(s):

Zhenke Zhu ◽

Guanjun Zeng ◽

Tida Ge ◽

Yajun Hu ◽

Chengli Tong ◽

...

Keyword(s):

Priming Effect ◽

Nutrient Management ◽

C Sequestration ◽

Paddy Soils ◽

Soil Organic C ◽

Untreated Soil ◽

Organic C ◽

Soil C ◽

Rice Roots ◽

Native Soil

Abstract. The input of recently photosynthesized C has significant implications on soil organic C sequestration, and in paddy soils, both plants and soil microbes contribute to the overall C input. In the present study, we investigated the fate and priming effect of organic C from different sources by conducting a 300-day incubation study with four different 13C-labelled substrates: rice shoots (shoot-C), rice roots (root-C), rice rhizodeposits (rhizo-C), and microbe-assimilated C (micro-C). The efflux of both 13CO2 and 13CH4 indicated that the mineralization of C in shoot-C-, root-C-, rhizo-C-, and micro-C-treated soils rapidly increased at the beginning of the incubation and decreased gradually afterwards. The highest cumulative C mineralization was observed in root-C-treated soil (45.4 %), followed by shoot-C- (31.9 %), rhizo-C- (7.90 %), and micro-C-treated (7.70 %) soils, which corresponded with mean residence times of 39.5, 50.3, 66.2, and 195 days, respectively. Shoot and root addition increased C emission from native soil organic carbon (SOC), up to 11.4 and 2.3 times higher than that of the control soil by day 20, and decreased thereafter. Throughout the incubation period, the priming effect of shoot-C on CO2 and CH4 emission was strongly positive; however, root-C did not exhibit a significant positive priming effect. Although the total C contents of rhizo-C- (1.89 %) and micro-C-treated soils (1.90 %) were higher than those of untreated soil (1.81 %), no significant differences in cumulative C emissions were observed. Given that about 0.3 and 0.1 % of the cumulative C emission were derived from labelled rhizo-C and micro-C, we concluded that the soil organic C-derived emissions were lower in rhizo-C- and micro-C-treated soils than in untreated soil. This indicates that rhizodeposits and microbe-assimilated C could be used to reduce the mineralization of native SOC and to effectively improve soil C sequestration. The contrasting behaviour of the different photosynthesized C substrates suggests that recycling rice roots in paddies is more beneficial than recycling shoots and demonstrates the importance of increasing rhizodeposits and microbe-assimilated C in paddy soils via nutrient management.

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Estimates of soil organic carbon stocks in central Canada using three different approaches

Canadian Journal of Forest Research ◽

10.1139/x01-122 ◽

2002 ◽

Vol 32 (5) ◽

pp. 805-812 ◽

Cited By ~ 47

Author(s):

J S Bhatti ◽

M J Apps ◽

C Tarnocai

Keyword(s):

Surface Layer ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Soil Depth ◽

Peat Soil ◽

Regression Line ◽

Organic C ◽

Soil C ◽

Total Soil

This study compared three estimates of carbon (C) contained both in the surface layer (030 cm) and the total soil pools at polygon and regional scales and the spatial distribution in the three prairie provinces of western Canada (Alberta, Saskatchewan, and Manitoba). The soil C estimates were based on data from (i) analysis of pedon data from both the Boreal Forest Transect Case Study (BFTCS) area and from a national-scale soil profile database; (ii) the Canadian Soil Organic Carbon Database (CSOCD), which uses expert estimation based on soil characteristics; and (iii) model simulations with the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS2). At the polygon scale, good agreement was found between the CSOCD and pedon (the first method) total soil carbon values. Slightly higher total soil carbon values obtained from BFTCS averaged pedon data (the first method), as indicated by the slope of the regression line, may be related to micro- and meso-scale geomorphic and microclimate influences that are not accounted for in the CSOCD. Regional estimates of organic C from these three approaches for upland forest soils ranged from 1.4 to 7.7 kg C·m2 for the surface layer and 6.2 to 27.4 kg C·m2 for the total soil. In general, the CBM-CFS2 simulated higher soil C content compared with the field observed and CSOCD soil C estimates, but showed similar patterns in the total soil C content for the different regions. The higher soil C content simulated with CBM-CFS2 arises in part because the modelled results include forest floor detritus pool components (such as coarse woody debris, which account for 412% of the total soil pool in the region) that are not included in the other estimates. The comparison between the simulated values (the third method) and the values obtained from the two empirical approaches (the first two methods) provided an independent test of CBM-CFS2 soil simulations for upland forests soils. The CSOCD yielded significantly higher C content for peatland soils than for upland soils, ranging from 14.6 to 28 kg C·m2 for the surface layer and 60 to 181 kg C·m2 for the total peat soil depth. All three approaches indicated higher soil carbon content in the boreal zone than in other regions (subarctic, grassland).

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Decomposition of carbon adsorbed on iron (III)-treated clays and their effect on the stability of soil organic carbon and external carbon inputs

Biogeochemistry ◽

10.1007/s10533-021-00873-w ◽

2021 ◽

Author(s):

Mengyang You ◽

Xia Zhu-Barker ◽

Timothy A. Doane ◽

William R. Horwath

Keyword(s):

Organic Carbon ◽

Layer Structure ◽

Mineral Soil ◽

Clay Mineralogy ◽

Plant Residue ◽

C Mineralization ◽

Organic C ◽

Soil C ◽

Native Soil ◽

The Stability

AbstractThe interaction of organic carbon (OC) with clay and metals stabilizes soil carbon (C), but the influence of specific clay-metal-OC assemblages (flocs) needs further evaluation. This study aimed to investigate the stability of flocs in soil as affected by external C inputs. Flocs representing OC-mineral soil fractions were synthesized using dissolved organic C (DOC) combined with kaolinite (1:1 layer structure) or montmorillonite (2:1 layer structure) clays in the absence or presence of two levels of Fe (III) (named low or high Fe). Flocs were mixed with soil (classified as Luvisol) and incubated with or without 13C labelled plant residue (i.e., ryegrass) for 30 days. The CO2 emissions and DOC concentrations as well as their 13C signatures from all treatments were examined. Total C mineralization from flocs was approximately 70% lower than non-flocced DOC. The flocs made with montmorillonite had 16–43% lower C mineralization rate than those made with kaolinite with no Fe or low Fe. However, when flocs were made with high Fe, clay mineralogy did not significantly affect total C mineralization. A positive priming effect (PE) of flocs on native soil OC was observed in all treatments, with a stronger PE found in lower Fe treatments. The high-Fe clay flocs inhibited ryegrass decomposition, while the flocs made without clay had no impact on it. Interestingly, flocs significantly decreased the PE of ryegrass on native soil OC decomposition. These results indicate that the adsorption of DOC onto clay minerals in the presence of Fe (III) stabilizes it against decomposition processes and its stability increases as Fe in flocs increases. Flocs also protect soil OC from the PE of external degradable plant C input. This study showed that Fe level and clay mineralogy play an important role in controlling soil C stability.

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A review of sampling designs for the measurement of soil organic carbon in Australian grazing lands

The Rangeland Journal ◽

10.1071/rj09043 ◽

2010 ◽

Vol 32 (2) ◽

pp. 227 ◽

Cited By ~ 66

Author(s):

D. E. Allen ◽

M. J. Pringle ◽

K. L. Page ◽

R. C. Dalal

Keyword(s):

Microbial Biomass ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Plant Growth ◽

Temporal Change ◽

Organic C ◽

Soil C ◽

Efficient Sampling ◽

Soc Stock ◽

Grazing Lands

The accurate measurement of the soil organic carbon (SOC) stock in Australian grazing lands is important due to the major role that SOC plays in soil productivity and the potential influence of soil C cycling on Australia’s greenhouse gas emissions. However, the current sampling methodologies for SOC stock are varied and potentially conflicting. It was the objective of this paper to review the nature of, and reasons for, SOC variability; the sampling methodologies commonly used; and to identify knowledge gaps for SOC measurement in grazing lands. Soil C consists of a range of biological materials, in various SOC pools such as dissolved organic C, micro- and meso-fauna (microbial biomass), fungal hyphae and fresh plant residues in or on the soil (particulate organic C, light-fraction C), the products of decomposition (humus, slow pool C) and complexed organic C, and char and phytoliths (inert, passive or resistant C); and soil inorganic C (carbonates and bicarbonates). Microbial biomass and particulate or light-fraction organic C are most sensitive to management or land-use change; resistant organic C and soil carbonates are least sensitive. The SOC present at any location is influenced by a series of complex interactions between plant growth, climate, soil type or parent material, topography and site management. Because of this, SOC stock and SOC pools are highly variable on both spatial and temporal scales. This creates a challenge for efficient sampling. Sampling methods are predominantly based on design-based (classical) statistical techniques, crucial to which is a randomised sampling pattern that negates bias. Alternatively a model-based (geostatistical) analysis can be used, which does not require randomisation. Each approach is equally valid to characterise SOC in the rangelands. However, given that SOC reporting in the rangelands will almost certainly rely on average values for some aggregated scale (such as a paddock or property), we contend that the design-based approach might be preferred. We also challenge soil surveyors and their sponsors to realise that: (i) paired sites are the most efficient way of detecting a temporal change in SOC stock, but destructive sampling and cumulative measurement errors decrease our ability to detect change; (ii) due to (i), an efficient sampling scheme to estimate baseline status is not likely to be an efficient sampling scheme to estimate temporal change; (iii) samples should be collected as widely as possible within the area of interest; (iv) replicate of laboratory analyses is a critical step in being able to characterise temporal change. Sampling requirements for SOC stock in Australian grazing lands are yet to be explicitly quantified and an examination of a range of these ecosystems is required in order to assess the sampling densities and techniques necessary to detect specified changes in SOC stock and SOC pools. An examination of techniques that can help reduce sampling requirements (such as measurement of the SOC fractions that are most sensitive to management changes and/or measurement at specific times of the year – preferably before rapid plant growth – to decrease temporal variability), and new technologies for in situ SOC measurement is also required.

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Stability and storage of soil organic carbon in a heavy-textured Karst soil from south-eastern Australia

Soil Research ◽

10.1071/sr13296 ◽

2014 ◽

Vol 52 (5) ◽

pp. 476 ◽

Cited By ~ 13

Author(s):

Eleanor Hobley ◽

Garry R. Willgoose ◽

Silvia Frisia ◽

Geraldine Jacobsen

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Profile ◽

C Sequestration ◽

Mineral Association ◽

Radiocarbon Dates ◽

Organic C ◽

Soil C ◽

Eastern Australia ◽

Particle Size Fractionation

Both aggregation and mineral association have been previously found to enhance soil organic carbon (SOC) storage (the amount of organic C retained in a soil), and stability (the length of time organic C is retained in a soil). These mechanisms are therefore attractive targets for soil C sequestration. In this study, we investigate and compare SOC storage and stability of SOC associated with fine minerals and stored within aggregates using a combination of particle-size fractionation, elemental analysis and radiocarbon dating. In this heavy-textured, highly aggregated soil, SOC was found to be preferentially associated with fine minerals throughout the soil profile. By contrast, the oldest SOC was located in the coarsest, most highly aggregated fraction. In the topsoil, radiocarbon ages of the aggregate-associated SOC indicate retention times in the order of centuries. Below the topsoil, retention times of aggregate-SOC are in the order of millennia. Throughout the soil profile, radiocarbon dates indicate an enhanced stability in the order of centuries compared with the fine mineral fraction. Despite this, the radiocarbon ages of the mineral-associated SOC were in the order of centuries to millennia in the subsoil (30–100 cm), indicating that mineral-association is also an effective stabilisation mechanism in this subsoil. Our results indicate that enhanced SOC storage does not equate to enhanced SOC stability, which is an important consideration for sequestration schemes targeting both the amount and longevity of soil carbon.

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Differential long-term effects of climate change and management on stocks and distribution of soil organic carbon in productive grasslands

Biogeosciences Discussions ◽

10.5194/bgd-9-1055-2012 ◽

2012 ◽

Vol 9 (1) ◽

pp. 1055-1096 ◽

Cited By ~ 1

Author(s):

A. M. G. De Bruijn ◽

P. Calanca ◽

C. Ammann ◽

J. Fuhrer

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Climate Change Scenarios ◽

Long Term Effects ◽

Organic C ◽

Soil C ◽

The Impact ◽

Soc Stocks

Abstract. We studied the impact of climate change on the dynamics of soil organic carbon (SOC) stocks in productive grassland systems undergoing two types of management, an intensive type with frequent harvests and fertilizer applications and an extensive system where fertilization is omitted and harvests are fewer. The Oensingen Grassland Model was explicitly developed for this study. It was calibrated using measurements taken in a recently established permanent sward in Central Switzerland, and run to simulate SOC dynamics over 2001–2100 under three climate change scenarios assuming different elements of IPCC A2 emission scenarios. We found that: (1) management intensity dominates SOC until approximately 20 yr after grassland establishment. Differences in SOC between climate scenarios become significant after 20 yr and climate effects dominate SOC dynamics from approximately 50 yr after establishment, (2) carbon supplied through manure contributes about 60% to measured organic C increase in fertilized grassland. (3) Soil C accumulates particularly in the top 10 cm soil until 5 yr after establishment. In the long-term, C accumulation takes place in the top 15 cm of the soil profile, while C content decreases below this depth. The transitional depth between gains and losses of C mainly depends on the vertical distribution of root senescence and root biomass. We discuss the importance of previous land use on carbon sequestration potentials that are much lower at the Oensingen site under ley-arable rotation and with much higher SOC stocks than most soils under arable crops. We further discuss the importance of biomass senescence rates, because C balance estimations indicate that these may differ considerably between the two management systems.

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Negative priming effect of three kinds of biochar on the mineralization of native soil organic carbon

Land Degradation and Development ◽

10.1002/ldr.3147 ◽

2018 ◽

Vol 29 (11) ◽

pp. 3985-3994 ◽

Cited By ~ 7

Author(s):

Yuxue Liu ◽

Ying Chen ◽

Yuying Wang ◽

Haohao Lu ◽

Lili He ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Negative Priming ◽

Priming Effect ◽

Negative Priming Effect ◽

Native Soil

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Differential long-term effects of climate change and management on stocks and distribution of soil organic carbon in productive grasslands

Biogeosciences ◽

10.5194/bg-9-1997-2012 ◽

2012 ◽

Vol 9 (6) ◽

pp. 1997-2012 ◽

Cited By ~ 11

Author(s):

A. M. G. De Bruijn ◽

P. Calanca ◽

C. Ammann ◽

J. Fuhrer

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Climate Change Scenarios ◽

Long Term Effects ◽

Organic C ◽

Soil C ◽

The Impact ◽

Soc Stocks

Abstract. We studied the impact of climate change on the dynamics of soil organic carbon (SOC) stocks in productive grassland systems undergoing two types of management, an intensive type with frequent harvests and fertilizer applications and an extensive system without fertilization and fewer harvests. Simulations were conducted with a dedicated newly developed model, the Oensingen Grassland Model. It was calibrated using measurements taken in a recently established permanent sward in Central Switzerland, and run to simulate SOC dynamics over 2001–2100 under various climate change scenarios assuming different elements of IPCC A2 emission scenarios. We found that: (1) management intensity dominates SOC until approximately 20 years after grassland establishment. Differences in SOC between climate scenarios become significant after 20 years and climate effects dominate SOC dynamics from approximately 50 years after establishment. (2) Carbon supplied through manure contributes about 60 % to measured organic C increase in fertilized grassland. (3) Soil C accumulates particularly in the top 10 cm of the soil until 5 years after establishment. In the long-term, C accumulation takes place in the top 15 cm of the soil profile, while C content decreases below this depth. The transitional depth between gains and losses of C mainly depends on the vertical distribution of root senescence and root biomass. We discuss the importance of previous land use on carbon sequestration potentials that are much lower at the Oensingen site under ley-arable rotation with much higher SOC stocks than most soils under arable crops. We further discuss the importance of biomass senescence rates, because C balance estimations indicate that these may differ considerably between the two management systems.

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Decomposition of Carbon Adsorbed on Iron (III)-Treated Clays and Their Effect on the Stability of Soil Organic Carbon and External Carbon Inputs

10.21203/rs.3.rs-300654/v1 ◽

2021 ◽

Author(s):

Mengyang You ◽

Xia Zhu-Barker ◽

Timothy A. Doane ◽

William R. Horwath

Keyword(s):

Organic Carbon ◽

Layer Structure ◽

Mineral Soil ◽

Clay Mineralogy ◽

C Mineralization ◽

Organic C ◽

Soil C ◽

Native Soil ◽

Decomposition Processes ◽

The Stability

Abstract The interaction of organic carbon (OC) with clay and metals stabilizes soil carbon (C), but the influence of specific clay-metal-OC assemblages (flocs) needs further evaluation. Clay-metal-OC assemblages representing OC-mineral soil fractions were synthesized using dissolved organic C (DOC) combined with kaolinite (1:1 layer structure) or montmorillonite (2:1 layer structure) clays in the absence or presence of two levels of Fe (III). Flocs were mixed with soil and incubated for 30 days. Total C mineralization from flocs was approximately 70% lower than non-flocced DOC. The flocs made with montmorillonite had 16–43% lower C mineralization rate than those made with kaolinite with no Fe or low Fe. However, when flocs were made with high Fe, clay mineralogy did not significantly affect total C mineralization. A positive priming effect (PE) of flocs on native soil OC was observed in all treatments, with a stronger PE found in lower Fe treatments. The high-Fe clay flocs inhibited ryegrass decomposition, while the flocs made without clay had no impact on it. Interestingly, flocs significantly decreased the PE of ryegrass on native soil OC decomposition. These results indicate that the adsorption of DOC onto clay minerals in the presence of Fe (III) stabilizes it against decomposition processes and its stability increases as Fe in flocs increases. Flocs also protect soil OC from the PE of external degradable plant C input. This study showed that Fe level and clay mineralogy play an important role in controlling soil C stability.

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