Characterization of Soil Carbon Stocks in the City of Johannesburg

Soil organic carbon (SOC) is a crucial indicator of soil health and soil productivity. The long-term implications of rapid urbanization on sustainability have, in recent years, raised concern. This study aimed to characterize the SOC stocks in the Johannesburg Granite Dome, a highly urbanized and contaminated area. Six soil hydropedological groups; (recharge (deep), recharge (shallow), responsive (shallow), responsive (saturated), interflow (A/B), and interflow (soil/bedrock)) were identified to determine the vertical distribution of the SOC stocks and assess the variation among the soil groups. The carbon (C) content, bulk density, and soil depth were determined for all soil groups, and thereafter the SOC stocks were calculated. Organic C stocks in the A horizon ranged, on average, from 33.55 ± 21.73 t C ha−1 for recharge (deep) soils to 17.11 ± 7.62 t C ha−1 for responsive (shallow) soils. Higher C contents in some soils did not necessarily indicate higher SOC stocks due to the combined influence of soil depth and bulk density. Additionally, the total SOC stocks ranged from 92.82 ± 39.2 t C ha−1 for recharge (deep) soils to 22.81 ± 16.84 t C ha−1 for responsive (shallow) soils. Future studies should determine the SOC stocks in urban areas, taking diverse land-uses and the presence of iron (Fe) oxides into consideration. This is crucial for understanding urban ecosystem functions.

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Spatial variability in terrestrial and aquatic carbon stocks and fluxes in boreal forested catchments

10.5194/egusphere-egu2020-5558 ◽

2020 ◽

Author(s):

Nora Casson ◽

Adrienne Ducharme ◽

Geethani Amarawansha ◽

Geoff Gunn ◽

Scott Higgins ◽

...

Keyword(s):

Spatial Variability ◽

Soil Depth ◽

Organic C ◽

Soil C ◽

C Pools ◽

Sampling Campaign ◽

C Stocks ◽

Doc Export ◽

Rain Events ◽

C Pools And Fluxes

<p>Canada&#8217;s boreal zone is a complex mosaic of forests, wetlands, streams and lakes.&#160; The pool of carbon (C) stored in each of these ecosystem components is vast, and significant to the global C balance.&#160; However, C pools and fluxes are heterogeneous in time and space, which contributes to uncertainty in predicting how a changing climate will affect the fate of C in these sensitive ecosystems. The objective of this study was to investigate factors controlling spatial variability in soil C stocks and stream C export and assess the sensitivity of these stocks and fluxes to climatic factors. We conducted a detailed examination of soil C stocks and stream dissolved organic C (DOC) export from a 320 ha boreal forested catchment located in northwestern Ontario, Canada. High-frequency stream chemistry and discharge samples were collected from three inflow streams during snowmelt and rain events from 2016-2017. An intensive soil C sampling campaign resulting in 47 surface (0 &#8211; 30 cm) samples were collected during the summer of 2019. Stream hysteresis analysis revealed marked differences in flowpaths among sub-catchments during snowmelt and rain events. In the wetland-dominated catchment, near-stream sources contributed most of the DOC export during both rainstorms and snowmelt events, but in upland-dominated catchments, the sources of DOC depended on antecedent moisture conditions. Rainstorms in these catchments following prolonged droughts resulted in DOC flushing from distal regions of the catchment. Soil C stocks were also highly spatially variable, with much of the variability being explained by local-scale factors (e.g. gravel content, soil depth, distance to the nearest ridge). Taken together, these two findings emphasize the need to consider sub-catchment scale variability when calculating C pools and fluxes in boreal catchments. This is also important when predicting how C dynamics will shift in the future as a result of shorter winters, longer droughts and more intense rainstorms.</p>

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Assessment of soil carbon stock of some selected agroecological zones of Bangladesh

Bangladesh Journal of Agricultural Research ◽

10.3329/bjar.v38i4.18947 ◽

2014 ◽

Vol 38 (4) ◽

pp. 625-635 ◽

Cited By ~ 1

Author(s):

PK Saha ◽

MS Rahman ◽

M Khatun ◽

ATMS Hossain ◽

MA Saleque

Keyword(s):

Bulk Density ◽

Soil Depth ◽

Soil Bulk Density ◽

Piedmont Plain ◽

Soil Carbon Stock ◽

Agroecological Zones ◽

Soc Stock ◽

Land Types ◽

Brahmaputra Floodplain ◽

Soc Stocks

The present investigation assessed the soil organic carbon (SOC) stocks of four AEZs in Bangladesh which included AEZ 1 (Old Himalayan Piedmont Plain), AEZ 3 (Tista Meander Floodplain), AEZ 4 (Karatoya-Bangali Floodplain), and AEZ 9 (Old Brahmaputra Floodplain). Three land types high land (HL), medium high and (MHL) and low and (LL) were considered in the SOC assessment. The SOC stock was estimated by multiplying SOC (%) with bulk density (g/cc) and soil depth (cm). Across the AEZs and land types, the SOC (%) decreased with the increase in soil depth. The SOC (%) was the highest in the low land and the lowest in the high land over the AEZs. The soil bulk density in every AEZ increased with soil depth. Bulk density of soil for medium high and varied from 1.26 g/cc to 1.67 g/cc, for high and from 1.33 g/cc to 1.55 g/cc, and for low land it was 1.13 g/cc to 1.44 g/cc. The SOC stock at 0-20 cm depth was higher (14.19-4.67 t/ha) in low land followed by medium high land (8.25-4.58 t/ha) and high land (6.46-3.39 t/ha) for all AEZs. Among the four AEZs, the highest SOC stock was found in AEZ 1 irrespective of land types. DOI: http://dx.doi.org/10.3329/bjar.v38i4.18947 Bangladesh J. Agril. Res. 38(4): 625-635, December 2013

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A cost-efficient method to assess carbon stocks in tropical peat soil

Biogeosciences ◽

10.5194/bg-9-4477-2012 ◽

2012 ◽

Vol 9 (11) ◽

pp. 4477-4485 ◽

Cited By ~ 39

Author(s):

M. W. Warren ◽

J. B. Kauffman ◽

D. Murdiyarso ◽

G. Anshari ◽

K. Hergoualc'h ◽

...

Keyword(s):

Soil Carbon ◽

Bulk Density ◽

National Parks ◽

Original Data ◽

Carbon Stocks ◽

Carbon Density ◽

Organic C ◽

C Stocks ◽

Soil Carbon Density ◽

Belowground Carbon

Abstract. Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m−3; Cd) as a function of bulk density (gC cm−3; Bd), which can be used to rapidly estimate belowground carbon storage using Bd measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (Cd = Bd × 495.14 + 5.41, R2 = 0.93, n = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm−3, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation Cd = Bd × 468.76 + 5.82, with R2 = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease Cd estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%.

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Increasing soil carbon stocks in eight permanent forest plots in China

Biogeosciences ◽

10.5194/bg-17-715-2020 ◽

2020 ◽

Vol 17 (3) ◽

pp. 715-726 ◽

Cited By ~ 1

Author(s):

Jianxiao Zhu ◽

Chuankuan Wang ◽

Zhang Zhou ◽

Guoyi Zhou ◽

Xueyang Hu ◽

...

Keyword(s):

Forest Soils ◽

Direct Evidence ◽

Net Primary Production ◽

Soil Depth ◽

Field Measurements ◽

Organic C ◽

Soil Carbon Stocks ◽

Soc Stock ◽

Soc Stocks ◽

Different Climates

Abstract. Forest soils represent a major stock of organic carbon (C) in the terrestrial biosphere, but the dynamics of soil organic C (SOC) stock are poorly quantified, largely due to lack of direct field measurements. In this study, we investigated the 20-year changes in SOC stocks in eight permanent forest plots, which represent boreal (1998–2014), temperate (1992–2012), subtropical (1987–2008), and tropical forest biomes (1992–2012) across China. SOC contents increased significantly from the 1990s to the 2010s, mostly in the upper 0–20 cm soil depth, and soil bulk densities do not change significantly during the same period. As a result, the averaged SOC stocks increased significantly from 125.2±85.2 Mg C ha−1 in the 1990s to 133.6±83.1 Mg C ha−1 in the 2010s across the forest plots, with a mean increase of 127.2–907.5 kg C ha−1 yr−1. This SOC accumulation resulted primarily from increasing leaf litter and fallen logs, which accounts 3.6 %–16.3 % of above-ground net primary production. Our findings provided direct evidence that China's forest soils have been acting as significant C sinks, although their strength varies in forests with different climates.

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Quantifying the effects of switchgrass (Panicum virgatum) on deep organic C stocks using natural abundance 14C in three marginal soils

10.1101/2020.07.07.190587 ◽

2020 ◽

Author(s):

Eric W. Slessarev ◽

Erin E. Nuccio ◽

Karis J. McFarlane ◽

Christina Ramon ◽

Malay Saha ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Panicum Virgatum ◽

Sandy Loam ◽

Mixing Model ◽

Bioenergy Crops ◽

Organic C ◽

C Stocks ◽

C Stock ◽

Soc Stocks

AbstractPerennial bioenergy crops have been shown to increase soil organic carbon (SOC) stocks, potentially offsetting anthropogenic C emissions. The effects of perennial bioenergy crops on SOC are typically assessed at shallow depths (< 30 cm), but the deep root systems of these crops may also have substantial effects on SOC stocks at greater depths. We hypothesized that deep (> 30 cm) soil organic carbon (SOC) stocks would be greater under bioenergy crops relative to stocks under shallow-rooted conventional crop cover. To test this, we sampled soils to between 1- and 3-meters depth at three sites in Oklahoma with 10-20 year old switchgrass (Panicum virgatum) stands, and collected paired samples from nearby fields cultivated with shallow rooted annual crops. We measured root biomass, total organic C, 14C, 13C, and other soil properties in three replicate soil cores in each field and used a mixing model to estimate the proportion of recently fixed C under switchgrass based on 14C. The subsoil C stock under switchgrass (defined over 500-1500 kg m-2 equivalent soil mass, approximately 30-100 cm depth) exceeded the subsoil stock in neighboring fields by 1.5 kg C m-2 at a sandy loam site, 0.6 kg C m-2 at a site with loam soils, and showed no significant difference at a third site with clay soils. Using the mixing model, we estimated that additional SOC introduced after switchgrass cultivation comprised 31% of the subsoil C stock at the sandy loam site, 22% at the loam site, and 0% at the clay site. These results suggest that switchgrass can contribute significantly to subsoil organic C—but also indicated that this effect varies across sites. Our analysis shows that agricultural strategies that emphasize deep-rooted grass cultivars can increase soil C relative to conventional crops while expanding energy biomass production on marginal lands.

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Effective Water Use—Irrigation

Handbook of Soils for Landscape Architects ◽

10.1093/oso/9780195121025.003.0010 ◽

1999 ◽

Author(s):

Robert F. Keefer

Keyword(s):

Soil Texture ◽

Soil Depth ◽

Ground Cover ◽

Rooting Depth ◽

Additional Increase ◽

Available Water ◽

Water Equilibrium ◽

Water Plants ◽

Shallow Soils ◽

Deep Soils

Soils that are suitable for irrigation are deep soils that are permeable and have a high available water-holding capacity (usually containing much organic matter). Limitations for irrigation include presence of restrictive layers (pans), erodible soils, sloping land, susceptibility to stream overflow, salinity or alkalinity, stoniness, and hazard of soil blowing. The amount of plant-available water in a soil depends on rooting depth and soil texture. Coarse textured sands hold much less available water than finer textured clayey soils. Available water increases as the texture becomes finer up to a silt loam. Any soil texture finer than that results in no additional increase in available water. In shallow soils, the rooting depth is limited by the soil depth. In deep soils, root depth is determined by the kind of plants present: . . . Trees and large shrubs 48 inches depth Medium shrubs and vines 40 inches depth Small shrubs and ground cover 24 inches depth . . . A number of techniques can be used to determine when water should be applied to soil in which plants are growing. These techniques include observing the plants, especially for wilting; feeling the soil; using tensiometers or electrical resistance meters installed in the soil; and measuring temperatures of plant leaves. Wilting—When plants begin to lose water they droop and wilting results. If plants remain in this condition very long, they soon die. It is better to water plants before they become wilted. Any plant that is wilted will require some time to reestablish its water equilibrium, thereby slowing the growth of that plant. The amount of moisture in a soil can be roughly estimated by the “feel method”. The degree of moisture can be determined by rolling or squeezing the soil into a ball. The soil moisture condition can be divided into six categories from dry to very wet: . . . a. If a ball will not form → soil is too dry for plants. b. If the ball formed will not crumble when rubbed → soil is too wet for plants. . . .

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Long-term effects of different land use and soil management on various organic carbon fractions in an Inceptisol of subtropical India

Soil Research ◽

10.1071/sr06077 ◽

2007 ◽

Vol 45 (1) ◽

pp. 33 ◽

Cited By ~ 15

Author(s):

T. J. Purakayastha ◽

P. K. Chhonkar ◽

S. Bhadraray ◽

A. K. Patra ◽

V. Verma ◽

...

Keyword(s):

Land Use ◽

Bulk Density ◽

Soil Depth ◽

Soil Layer ◽

Soil Management ◽

Irrigated Rice ◽

Organic C ◽

Microbial Quotient ◽

Uncultivated Soil ◽

Agro Forestry

Land use changes, especially the conversion of native forest vegetation to cropland and plantations in tropical regions, can potentially alter soil C dynamics. A study was conducted to assess the effects of various land uses and soil managements (agro-forestry plantation, vegetable field, tube-well irrigated rice–wheat, sewage-irrigated rice–wheat, and uncultivated soils) on soil pH, bulk density, soil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), C mineralisation (Cmin), microbial quotient, and microbial metabolic quotient (qCO2) in 0−0.05, 0.05−0.10, and 0.10−0.20 m soil depths. At 0−0.05 m, the bulk density was lowest (1.29 Mg/m3) in agro-forestry soil, whereas the uncultivated soil (jointly with vegetable field soil) showed highest bulk density (1.48 Mg/m3). Sewage-irrigated rice–wheat soil showed lowest pH particularly in the 0−0.05 and 0.10−0.20 m soil layer. Irrespective of soil depths, agro-forestry plantation showed greater SOC followed by sewage-irrigated rice–wheat soil. Nevertheless, agro-forestry soil also showed highest stock of SOC (33.7 Mg/ha), POC (3.58 Mg/ha), and MBC (0.81 Mg/ha) in the 0−0.20 m soil layer. Sewage-irrigated rice–wheat jointly with agro-forestry soil showed greatest Cmin in the 0−0.20 m soil layer, although the former supported lower SOC stock. The decrease in SOC (SOC0−0.05 m/SOC0.10−0.20 m) and Cmin (Cmin 0−0.05 m/Cmin 0.10−0.20 m) along soil depth was significantly higher in the agro-forestry system than in most of the other land use and soil management systems. Microbial quotient was highest in sewage-irrigated rice–wheat soil, particularly in the 0−0.05 m soil depth, whereas qCO2 was greater in uncultivated soil. In general, microbial quotients decreased, whereas qCO2 increased down the soil profile.

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Sustainable Management of Soil for Carbon Sequestration

Science & Technology Journal ◽

10.22232/stj.2017.05.02.10 ◽

2017 ◽

Vol 5 (2) ◽

pp. 132-140 ◽

Cited By ~ 1

Author(s):

Kewat Sanjay Kumar ◽

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Sustainable Management ◽

Management Practices ◽

Atmospheric Co2 ◽

Carbon Pools ◽

Carbon Stabilization ◽

Organic C ◽

Soil Ecosystems ◽

C Stocks

Mechanisms governing carbon stabilization in soils have received a great deal of attention in recent years due to their relevance in the global carbon cycle. Two thirds of the global terrestrial organic C stocks in ecosystems are stored in below ground components as terrestrial carbon pools in soils. Furthermore, mean residence time of soil organic carbon pools have slowest turnover rates in terrestrial ecosystems and thus there is vast potential to sequester atmospheric CO2 in soil ecosystems. Depending upon soil management practices it can be served as source or sink for atmospheric CO2. Sustainable management systems and practices such as conservation agriculture, agroforestry and application of biochar are emerging and promising tools for soil carbon sequestration. Increasing soil carbon storage in a system simultaneously improves the soil health by increase in infiltration rate, soil biota and fertility, nutrient cycling and decrease in soil erosion process, soil compaction and C emissions. Henceforth, it is vital to scientifically explore the mechanisms governing C flux in soils which is poorly understood in different ecosystems under anthropogenic interventions making soil as a potential sink for atmospheric CO2 to mitigate climate change. Henceforth, present paper aims to review basic mechanism governing carbon stabilization in soils and new practices and technological developments in agricultural and forest sciences for C sequestration in terrestrial soil ecosystems.

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The Soil Organic Matter in Connection with Soil Properties and Soil Inputs

Agronomy ◽

10.3390/agronomy11040779 ◽

2021 ◽

Vol 11 (4) ◽

pp. 779

Author(s):

Václav Voltr ◽

Ladislav Menšík ◽

Lukáš Hlisnikovský ◽

Martin Hruška ◽

Eduard Pokorný ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Texture ◽

Management Practices ◽

Soil Depth ◽

Operating Conditions ◽

Hot Water ◽

Natural Soil ◽

Soil Productivity ◽

Linear Regression Models

The content of organic matter in the soil, its labile (hot water extractable carbon–HWEC) and stable (soil organic carbon–SOC) form is a fundamental factor affecting soil productivity and health. The current research in soil organic matter (SOM) is focused on individual fragmented approaches and comprehensive evaluation of HWEC and SOC changes. The present state of the soil together with soil’s management practices are usually monitoring today but there has not been any common model for both that has been published. Our approach should help to assess the changes in HWEC and SOC content depending on the physico-chemical properties and soil´s management practices (e.g., digestate application, livestock and mineral fertilisers, post-harvest residues, etc.). The one- and multidimensional linear regressions were used. Data were obtained from the various soil´s climatic conditions (68 localities) of the Czech Republic. The Czech farms in operating conditions were observed during the period 2008–2018. The obtained results of ll monitored experimental sites showed increasing in the SOC content, while the HWEC content has decreased. Furthermore, a decline in pH and soil´s saturation was documented by regression modelling. Mainly digestate application was responsible for this negative consequence across all soils in studied climatic regions. The multivariate linear regression models (MLR) also showed that HWEC content is significantly affected by natural soil fertility (soil type), phosphorus content (−30%), digestate application (+29%), saturation of the soil sorption complex (SEBCT, 21%) and the dose of total nitrogen (N) applied into the soil (−20%). Here we report that the labile forms (HWEC) are affected by the application of digestate (15%), the soil saturation (37%), the application of mineral potassium (−7%), soil pH (−14%) and the overall condition of the soil (−27%). The stable components (SOM) are affected by the content of HWEC (17%), soil texture 0.01–0.001mm (10%), and input of organic matter and nutrients from animal production (10%). Results also showed that the mineral fertilization has a negative effect (−14%), together with the soil depth (−11%), and the soil texture 0.25–2 mm (−21%) on SOM. Using modern statistical procedures (MRLs) it was confirmed that SOM plays an important role in maintaining resp. improving soil physical, biochemical and biological properties, which is particularly important to ensure the productivity of agroecosystems (soil quality and health) and to future food security.

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