Opening the black box: Soil microcosm experiments reveal soot black carbon short-term oxidation and influence on soil organic carbon mineralisation

Black carbon (BC), the product of the incomplete combustion of fossil fuels and biomass, is ubiquitous in soils globally. Although BC is a major soil carbon pool, its effects on the global carbon cycle have not yet been resolved. It is deemed to represent a large stable pool in soils turning over on geological timescales, but research suggests it can alter soil biogeochemical cycling including that of ecosystem-derived organic carbon. Here, we established two soil microcosm chamber experiments: experiment one added 13C organic carbon to soil with and without added BC (soot and biochar) to investigate whether it suppressed organic carbon mineralisation; experiment two added 13C BC (soot) to soil to establish whether it is mineralised in soil over a short timescale. Gases were sampled over six-months and analysed using isotope ratio mass spectrometry. In experiment one we found that the efflux of 13C organic carbon from the soil decreased over time, but the addition of soot to soil significantly reduced the mineralisation of organic carbon from 32% of the total supplied without soot to 14% of the total supplied with soot. In contrast, there was not a significant difference after the addition of biochar in the flux of &#948; 13CO2 from the organic carbon added to the soil. In experiment two, we found that the efflux 13C from soil with added 13C labelled soot significantly differed from the control, but this efflux declined over time. There was a cumulative loss of 0.17% 13C from soot over the experiment.These experimental results represent a step-change in understanding the influence of BC continuum on carbon dynamics, which has major consequences for the way we measure, monitor and manage soils for carbon storage and sequestration in the future.

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Stover management modifies soil organic carbon dynamics in the short-term under semiarid continuous maize

Soil and Tillage Research ◽

10.1016/j.still.2021.105143 ◽

2021 ◽

Vol 213 ◽

pp. 105143

Author(s):

Jorge Álvaro-Fuentes ◽

Samuel Franco-Luesma ◽

Victoria Lafuente ◽

Pablo Sen ◽

Asun Usón ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Dynamics ◽

Short Term ◽

Continuous Maize ◽

Soil Organic Carbon Dynamics

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Effects of Management and Hillside Position on Soil Organic Carbon Stratification in Mediterranean Centenary Olive Grove

Agronomy ◽

10.3390/agronomy11040650 ◽

2021 ◽

Vol 11 (4) ◽

pp. 650

Author(s):

Jesús Aguilera-Huertas ◽

Beatriz Lozano-García ◽

Manuel González-Rosado ◽

Luis Parras-Alcántara

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Quality ◽

Management Practices ◽

Soil Management ◽

Olive Grove ◽

No Tillage ◽

Short Term ◽

Degradation Degree

The short- and medium—long-term effects of management and hillside position on soil organic carbon (SOC) changes were studied in a centenary Mediterranean rainfed olive grove. One way to measure these changes is to analyze the soil quality, as it assesses soil degradation degree and attempts to identify management practices for sustainable soil use. In this context, the SOC stratification index (SR-COS) is one of the best indicators of soil quality to assess the degradation degree from SOC content without analyzing other soil properties. The SR-SOC was calculated in soil profiles (horizon-by-horizon) to identify the best soil management practices for sustainable use. The following time periods and soil management combinations were tested: (i) in the medium‒long-term (17 years) from conventional tillage (CT) to no-tillage (NT), (ii) in the short-term (2 years) from CT to no-tillage with cover crops (NT-CC), and (iii) the effect in the short-term (from CT to NT-CC) of different topographic positions along a hillside. The results indicate that the SR-SOC increased with depth for all management practices. The SR-SOC ranged from 1.21 to 1.73 in CT0, from 1.48 to 3.01 in CT1, from 1.15 to 2.48 in CT2, from 1.22 to 2.39 in NT-CC and from 0.98 to 4.16 in NT; therefore, the soil quality from the SR-SOC index was not directly linked to the increase or loss of SOC along the soil profile. This demonstrates the time-variability of SR-SOC and that NT improves soil quality in the long-term.

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Short-Term Crop Rotation and Tillage Effects on Soil Organic Carbon on the Canadian Prairies

Agricultural Practices and Policies for Carbon Sequestration in Soil ◽

10.1201/9781420032291-31 ◽

2016 ◽

pp. 311-320

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Crop Rotation ◽

Short Term ◽

Canadian Prairies

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Soil organic carbon accumulation and carbon dioxide emissions during a 6-year study in irrigated continuous maize under two tillage systems in semiarid Mediterranean conditions

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2021191-16260 ◽

2021 ◽

Vol 19 (1) ◽

pp. e1102

Author(s):

Maroua Dachraoui ◽

Aurora Sombrero

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Temperature ◽

Grain Yield ◽

Co2 Emissions ◽

Carbon Dioxide Emissions ◽

Carbon Accumulation ◽

No Tillage ◽

Short Term ◽

The Impact

Aim of study: To evaluate the effects of conventional tillage (CT) and no tillage (NT) systems on the soil organic carbon (SOC) changes, CO2 emissions and their relation with soil temperature and grain yield in a monoculture of irrigated maize during six years.Area of study: In Zamadueñas experimental field in the Spanish province of Valladolid, from 2011 to 2017.Material and methods: The SOC content was determined by collecting soil samples up to 30 cm in November at two years interval. Short-term CO2 emissions were measured simultaneously with soil temperature using a respiration chamber and a hand-held probe immediately before, after every tillage operation and during the maize cycle.Main results: The SOC stock of the top 30 cm soil layers was 13% greater under NT than CT. Short-term CO2 emissions were significantly higher under CT ranging from 0.8 to 3.4 g CO2 m-2 h-1 immediately after tillage while under NT system, soil CO2 fluxes were low and stable during this study period. During the first 48 h following tillage, cumulative CO2 emissions ranged from 0.6 to 2.4 Mg CO2 ha-1 and from 0.2 to 0.3 Mg CO2 ha-1 under CT and NT systems, respectively. Soil temperature did not show significant correlation with CO2 emissions; however, it depended mostly on the time of measurement.Research highlights: No tillage increased the SOC accumulation in the topsoil layer, reduced CO2 emissions without decreasing maize grain yield and minimized the impact on climate change compared to CT system.

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