Short-Term Effect of Sugarcane Straw on Soil Organic Carbon Pools

This study aimed to evaluate the short-term effect of sugarcane straw on soil organic carbon (SOC) stocks in tropical soils. The treatments simulated the maintenance of different rates of sugarcane straw (0, 2.2, 5.1, 7.8 and 12 t ha-1) applied on the soil surface, with four replication, and evaluated chemical and biological attributes in four depths (0-0.05; 0.05-0.10; 0.10-0.20; 0.20-0.40 m). Results from soil samples collected in the rainy and dry seasons showed evidence of positive short-term effects of green harvest either on labile and humified soil organic matter (SOM) pools. For the total SOC stocks, we observed linear responses with straw rates in both sampling seasons. A decreased humification index in the topsoil suggests more labile C pools available in the soil, resulting in a significant increase in microbial activity. Microbial indicators point towards a steady equilibrium in SOC turnover, which can lead to future lower increases in SOC stocks if high straw amounts are maintained on the soil surface. Therefore, long-term studies under low-latitude areas are necessary to model the potential of C sequestration in sugarcane green harvest systems.

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Increased Iron-Carbon Interactions Under Long-Term Acid Deposition Enhance Soil Organic Carbon Sequestration in A Tropical Forest in Southern China

10.21203/rs.3.rs-570953/v1 ◽

2021 ◽

Author(s):

Jingwen Chen ◽

Yuanliu Hu ◽

Steven J. Hall ◽

Dafeng Hui ◽

Jianling Li ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Tropical Forest ◽

Acid Deposition ◽

Southern China ◽

Base Cations ◽

Tropical Soils ◽

C Sequestration ◽

Ph Sensitive ◽

Soil C

Abstract Atmospheric acid deposition remains a widespread problem that may influence the protection of carbon (C) in soil by altering organo-mineral interactions. However, the impacts of additional acidity on organo-mineral interactions and soil C sequestration in naturally acidic tropical soils with a high content of reactive iron (Fe) phases have not been well studied. Here we sampled a nearly 10-yr field experiment with a gradient of acidity treatments (0, 9.6, 32, 96 mol H+ ha− 1 yr− 1 as nitric acid + sulfuric acid) to examine how acidification alters organo-mineral interactions and soil organic carbon (SOC) pools in a tropical forest in southern China. As expected, soil acidification significantly enhanced the leaching of base cations (e.g., Ca2+), and it also altered the solubility and composition of Fe and Al phases. The acidity treatments converted more crystalline Fe (oxyhydr)oxides to short-range-ordered phases, resulting in a large increase in Fe-bound C vs. a relatively small decrease in Ca-bound C. Overall, the acidity treatments increased the mineral-associated C stock to 32.5–36.4 Mg C ha− 1 vs. 28.8 Mg C ha− 1 in the control, accounting for 71–83% of the observed increase in total SOC stock. These findings highlight the importance of pH-sensitive geochemical changes and the key roles of Fe in regulating the response of SOC to further inputs of acid deposition even in highly weathered and naturally acidic soils. The magnitude of SOC changes observed here indicates the importance of including pH-sensitive geochemistry in Earth system models to predict ecosystem C budgets under future acid deposition scenarios.

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Global distribution of soil organic carbon – Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world

SOIL ◽

10.5194/soil-1-351-2015 ◽

2015 ◽

Vol 1 (1) ◽

pp. 351-365 ◽

Cited By ~ 138

Author(s):

M. Köchy ◽

R. Hiederer ◽

A. Freibauer

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Bulk Density ◽

Tropical Soils ◽

Frequency Distributions ◽

Tropical Regions ◽

The World ◽

Global Soil ◽

Soc Stocks

Abstract. The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg when using the original values for bulk density. Adjusting the HWSD's bulk density (BD) of soil high in organic carbon results in a mass of 1230 Pg, and additionally setting the BD of Histosols to 0.1 g cm−3 (typical of peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols alone introduces a range of −56 to +180 Pg C into the estimate of global SOC mass in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. With more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils, whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

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Soil carbon market-based instrument pilot – the sequestration of soil organic carbon for the purpose of obtaining carbon credits

Soil Research ◽

10.1071/sr19331 ◽

2021 ◽

Vol 59 (1) ◽

pp. 12 ◽

Cited By ~ 1

Author(s):

Warwick Badgery ◽

Brian Murphy ◽

Annette Cowie ◽

Susan Orgill ◽

Andrew Rawson ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Organic Amendments ◽

C Sequestration ◽

Total Carbon ◽

Emissions Reduction ◽

Reduced Tillage ◽

Permanent Pasture ◽

Soc Stocks

Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha–1 year–1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha–1 year–1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.

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Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

Biogeosciences ◽

10.5194/bg-14-1003-2017 ◽

2017 ◽

Vol 14 (4) ◽

pp. 1003-1019 ◽

Cited By ~ 13

Author(s):

Mathias Hoffmann ◽

Nicole Jurisch ◽

Juana Garcia Alba ◽

Elisa Albiac Borraz ◽

Marten Schmidt ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Spatial Heterogeneity ◽

Temporal Dynamics ◽

Small Scale ◽

Short Term ◽

C Cycle ◽

Spatial Differences ◽

Northeastern Germany ◽

Soc Stocks

Abstract. Carbon (C) sequestration in soils plays a key role in the global C cycle. It is therefore crucial to adequately monitor dynamics in soil organic carbon (ΔSOC) stocks when aiming to reveal underlying processes and potential drivers. However, small-scale spatial (10–30 m) and temporal changes in SOC stocks, particularly pronounced in arable lands, are hard to assess. The main reasons for this are limitations of the well-established methods. On the one hand, repeated soil inventories, often used in long-term field trials, reveal spatial patterns and trends in ΔSOC but require a longer observation period and a sufficient number of repetitions. On the other hand, eddy covariance measurements of C fluxes towards a complete C budget of the soil–plant–atmosphere system may help to obtain temporal ΔSOC patterns but lack small-scale spatial resolution. To overcome these limitations, this study presents a reliable method to detect both short-term temporal dynamics as well as small-scale spatial differences of ΔSOC using measurements of the net ecosystem carbon balance (NECB) as a proxy. To estimate the NECB, a combination of automatic chamber (AC) measurements of CO2 exchange and empirically modeled aboveground biomass development (NPPshoot) were used. To verify our method, results were compared with ΔSOC observed by soil resampling. Soil resampling and AC measurements were performed from 2010 to 2014 at a colluvial depression located in the hummocky ground moraine landscape of northeastern Germany. The measurement site is characterized by a variable groundwater level (GWL) and pronounced small-scale spatial heterogeneity regarding SOC and nitrogen (Nt) stocks. Tendencies and magnitude of ΔSOC values derived by AC measurements and repeated soil inventories corresponded well. The period of maximum plant growth was identified as being most important for the development of spatial differences in annual ΔSOC. Hence, we were able to confirm that AC-based C budgets are able to reveal small-scale spatial differences and short-term temporal dynamics of ΔSOC.

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Spatial variability in organic carbon stocks on level sites: Relation to vertical penetration of the A horizon

Canadian Journal of Soil Science ◽

10.4141/cjss08068 ◽

2009 ◽

Vol 89 (4) ◽

pp. 455-459 ◽

Cited By ~ 1

Author(s):

C Chan ◽

B D Kay ◽

E G Gregorich

Keyword(s):

Carbon Sequestration ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Spatial Variability ◽

Soil Profile ◽

Soil Surface ◽

Carbon Stocks ◽

Sampling Strategies ◽

Repeated Sampling ◽

Soc Stocks

Understanding the source of spatial variability in soil organic carbon (SOC) stocks will contribute to improved sampling strategies to detect changes in stocks. Most of the variability in SOC stocks in cores collected from small (2 × 3 m) level plots on seven soils with similar cropping histories was related to variation in A horizon depth. Increased variability in horizon depth within plots coincided with the development of zones where the A horizon penetrated to greater depths. Consequently, accurate estimates of SOC stocks cannot be made from shallow measurements at the soil surface (e.g., 10 cm) and minimizing the spatial variability in locations of repeated sampling is necessary when characterizing changes in SOC stocks.Key words: Carbon sequestration, soil organic carbon, spatial variability, soil profile, A horizon

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Global distribution of soil organic carbon, based on the Harmonized World Soil Database – Part 1: Masses and frequency distribution of SOC stocks for the tropics, permafrost regions, wetlands, and the world

SOIL Discussions ◽

10.5194/soild-1-327-2014 ◽

2014 ◽

Vol 1 (1) ◽

pp. 327-362 ◽

Cited By ~ 6

Author(s):

M. Köchy ◽

R. Hiederer ◽

A. Freibauer

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Bulk Density ◽

Tropical Soils ◽

Organic Soils ◽

Soil Database ◽

The World ◽

Global Soil ◽

Soc Stocks

Abstract. The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget. We review current estimates of soil organic carbon stocks (mass/area) and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg. Correcting the HWSD's bulk density of organic soils, especially Histosols, results in a mass of 1062 Pg. The uncertainty of bulk density of Histosols alone introduces a range of −56 to +180 Pg for the estimate of global SOC in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arc minutes, the areal masses of SOC and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. Incorporating more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Data Base (496 Pg SOC) and tropical peatland carbon, global soils contain 1324 Pg SOC in the upper 1 m including 421 Pg in tropical soils, whereof 40 Pg occur in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

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Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

10.5194/bg-2016-332 ◽

2016 ◽

Cited By ~ 1

Author(s):

Mathias Hoffmann ◽

Nicole Jurisch ◽

Juana Garcia Alba ◽

Elisa Albiac Borraz ◽

Marten Schmidt ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Spatial Heterogeneity ◽

Temporal Dynamics ◽

Small Scale ◽

Ground Moraine ◽

Short Term ◽

Ne Germany ◽

C Cycle ◽

Soc Stocks

Abstract. Carbon (C) sequestration in soils plays a key role in the global C cycle. It is therefore crucial to adequately monitor dynamics in soil organic carbon (∆SOC) stocks when aiming to reveal underlying processes and potential drivers. However, small-scale spatial and temporal changes in SOC stocks, particularly pronounced on arable lands, are hard to assess. The main reasons for this are limitations of the well-established methods. On the one hand, repeated soil inventories, often used in long-term field trials, reveal spatial patterns and trends in ∆SOC but require a longer observation period and a sufficient number of repetitions. On the other hand, eddy covariance measurements of C fluxes towards a complete C budget of the soil-plant-atmosphere system may help to obtain temporal ∆SOC patterns but lack small-scale spatial resolution. To overcome these limitations, this study presents a reliable method to detect both short-term temporal as well as small-scale spatial dynamics of ΔSOC. Therefore, a combination of automatic chamber (AC) measurements of CO2 exchange and empirically modeled aboveground biomass development (NPPshoot) was used. To verify our method, results were compared with ΔSOC observed by soil resampling. AC measurements were performed from 2010 to 2014 under a silage maize/winter fodder rye/sorghum-Sudan grass hybrid/alfalfa crop rotation at a colluvial depression located in the hummocky ground moraine landscape of NE Germany. Widespread in large areas of the formerly glaciated Northern Hemisphere, this depression type is characterized by a variable groundwater level (GWL) and pronounced small-scale spatial heterogeneity in soil properties, such as SOC and nitrogen (Nt). After monitoring the initial stage during 2010, soil erosion was experimentally simulated by incorporating topsoil material from an eroded midslope soil into the plough layer of the colluvial depression. SOC stocks were quantified before and after soil manipulation and at the end of the study period. AC-based ∆SOC values corresponded well with the tendencies and magnitude of the results observed in the repeated soil inventory. The period of maximum plant growth was identified as being most important for the development of spatial differences in annual ΔSOC. Hence, we were able to confirm that AC-based C budgets are able to reveal small-scale spatial and short-term temporal dynamics of ∆SOC.

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A Newspaper’s Effect on the Strength of Automatic Associations in Memory

Journal of Media Psychology Theories Methods and Applications ◽

10.1027/1864-1105/a000057 ◽

2012 ◽

Vol 24 (1) ◽

pp. 1-8 ◽

Cited By ~ 12

Author(s):

Florian Arendt

Keyword(s):

Treatment Group ◽

Term Effect ◽

Control Group ◽

Implicit Measure ◽

Short Term ◽

Short Term Treatment ◽

Short Term Effect ◽

Automatic Associations ◽

Foreign Nationality ◽

The Impact

A test was done to see if reading a newspaper which consistently overrepresents foreigners as criminals strengthens the automatic association between foreign country and criminal in memory (i.e., implicit cultivation). Further, an investigation was done to find out if reading articles from the same newspaper produces a short-term effect on the same measure and if (1) emotionalization of the newspaper texts, (2) emotional reactions of the reader (indicated by arousal), and (3) attributed text credibility moderate the short-term treatment effect. Eighty-five participants were assigned to one of three experimental conditions. Participants in the control group received short factual crime texts, where the nationality of the offender was not mentioned. Participants in the factual treatment group received the same texts, but the foreign nationality was mentioned. Participants in the emotionalized treatment group received emotionalized articles (i.e., texts which are high in vividness and frequency) covering the same crimes, with the foreign nationality mentioned. Supporting empirical evidence for implicit cultivation and a short-term effect was found. However, only emotionalized articles produced a short-term effect on the strength of the automatic association, indicating that newspaper texts must have a minimum of stimulus intensity to overcome an effect threshold. There were no moderating effects of arousal or credibility pertaining to the impact on the implicit measure. However, credibility moderated the short-term effect on a first-order judgment (i.e., estimated frequency of foreigners of all criminals). This indicates that a newspaper’s effect on the strength of automatic associations is relatively independent from processes of propositional reasoning.

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