scholarly journals Are human activities main drivers of soil organic carbon losses in mountain rainfed agroecosystems?

2020 ◽  
Author(s):  
Ivan Lizaga ◽  
Leticia Gaspar ◽  
Laura Quijano ◽  
Maria Concepción Ramos ◽  
Ana Navas
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Human Activities ◽  
Surface Soil ◽  
Extreme Event ◽  
Extreme Rainfall ◽  
Storm Event ◽  
Land Uses ◽  
Rainfed Agriculture ◽  
Carbon Fraction

<p>One of the principal soil degradation problems affecting European agroecosystems is the loss of topsoil by water erosion. In dry climates, soil erosion is led by two main factors, human activities such as agriculture and extreme episodic rainfalls. However, agriculture plays a crucial role in leaving the soils unprotected during part of the year. Thus, extreme rainfall can easily remove the topsoil with the subsequent removal of nutrients in surface soil layers and the reduction of soil quality.</p><p>To assess the effects of extreme storms in rainfed agriculture catchments on soil organic carbon removal, surface soil samples from different land uses were collected in a medium-sized catchment at the foot of Santo Domingo range. The study area was mostly cultivated at the beginning of the 19th century but changed to rangeland and afforestation forest in the last 50 years. The remaining cropland area is mostly rainfed agriculture that leaves soils unprotected in periods when erosive storms occur (autumn convective rainfalls). The main land uses are croplands, pine afforestation, scrubland and Mediterranean forest. To track the export of soil organic carbon associated to mobilised sediment occurring under storm events, channel bed sediment samples were collected along the principal streams of the drainage network during regular flow, after a regular storm event, and after an extreme storm event. The contents of soil organic carbon (SOC), SOC fractions and grain size were analysed and compared for the three sampling campaigns.  The results show a gradual decrease of the fine fraction from regular flood samples to samples collected after the extreme event. However, the SOC showed a sharp decrease in the post-extreme event samples, with higher decreases in the active carbon fraction (ACF) than in the stable carbon fraction (SCF).</p><p>Our findings highlight the substantial in situ hazards of extreme rainfall events removing soil organic carbon from topsoils and exporting fine sediment and nutrients out of the catchment with important indirect impacts on water resources both quantity and quality.</p>

Soil organic carbon stock in different urban land uses: high stock evidence in urban parks

2019 ◽  
Vol 23 (1) ◽  
pp. 159-171 ◽  
Author(s):  
Claudia Canedoli ◽  
Chiara Ferrè ◽  
Davide Abu El Khair ◽  
Emilio Padoa-Schioppa ◽  
Roberto Comolli
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Stock ◽  
Urban Parks ◽  
Urban Land ◽  
Land Uses ◽  
Soil Organic Carbon Stock ◽  
Organic Carbon Stock

scholarly journals Impact of carbonates on the mineralisation of surface soil organic carbon in response to shift in tillage practice

Geoderma ◽  
2019 ◽  
Vol 339 ◽  
pp. 94-105 ◽  
Author(s):  
Promil Mehra ◽  
Binoy Sarkar ◽  
Nanthi Bolan ◽  
Saikat Chowdhury ◽  
Jack Desbiolles
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Surface Soil ◽  
Tillage Practice

scholarly journals Soil organic carbon sequestration in soil aggregates in the karst Critical Zone Observatory, Southwest China

2019 ◽  
Vol 65 (No. 5) ◽  
pp. 253-259 ◽  
Author(s):  
Man Liu ◽  
Guilin Han ◽  
Zichuan Li ◽  
Qian Zhang ◽  
Zhaoliang Song
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Southwest China ◽  
Critical Zone ◽  
Soil Aggregation ◽  
Research Station ◽  
Land Uses ◽  
Farmland Abandonment ◽  
Critical Zone Observatory ◽  
Farmland Soils

Soil organic carbon (SOC) sequestration in aggregates under land use change have been widely concerned due to intimate impacts on the sink (or source) of atmospheric carbon dioxide (CO<sub>2</sub>). However, the quantitative relationship between soil aggregation and SOC sequestration under land uses change has been poorly studied. Distribution of aggregates, SOC contents in bulk soils and different size aggregates and their contributions to SOC sequestration were determined under different land uses in the Puding Karst Ecosystem Observation and Research Station, karst Critical Zone Observatory (CZO), Southwest China. Soil aggregation and SOC sequestration increased in the processes of farmland abandonment and recovery. SOC contents in micro-aggregates were larger than those in macro-aggregates in restored land soils, while the opposite results in farmland soils were obtained, probably due to the hindrance of the C-enriched SOC transport from macro-aggregate into micro-aggregate by the disturbance of agricultural activities. SOC contents in macro-aggregates exponentially increased with their proportions along successional land uses. Macro-aggregates accounted for over 80% on the SOC sequestration in restored land soils, while they accounted for 31–60% in farmland soils. These results indicated that macro-aggregates have a great potential for SOC sequestration in karst soils.

The chemical and physical stability soil organic carbon in the top 1 m of the soil profile under different land uses in the UK

2020 ◽  
Author(s):  
Dedy Antony ◽  
Jo Clark ◽  
Chris Collins ◽  
Tom Sizmur
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Profile ◽  
Soil Depth ◽  
Physical Stability ◽  
Silty Clay ◽  
Land Uses ◽  
Total N

&lt;p&gt;Soils are the largest terrestrial pool of organic carbon and it is now known that as much as 50% of soil organic carbon (SOC) can be stored below 30 cm. Therefore, knowledge of the mechanisms by which soil organic carbon is stabilised at depth and how land use affects this is important.&lt;/p&gt;&lt;p&gt;This study aimed to characterise topsoil and subsoil SOC and other soil properties under different land uses to determine the SOC stabilisation mechanisms and the degree to which SOC is vulnerable to decomposition. Samples were collected under three different land uses: arable, grassland and deciduous woodland on a silty-clay loam soil and analysed for TOC, pH, C/N ratio and texture down the first one metre of the soil profile. Soil organic matter (SOM) physical fractionation and the extent of fresh mineral surfaces were also analysed to elucidate SOM stabilisation processes.&lt;/p&gt;&lt;p&gt;Results showed that soil texture was similar among land uses and tended to become more fine down the soil profile, but pH did not significantly change with soil depth. Total C, total N and C/N ratio decreased down the soil profile and were affected by land use in the order woodland &gt; grassland &gt; arable. SOM fractionation revealed that the free particulate organic matter (fPOM) fraction was significantly greater in both the topsoil and subsoil under woodland than under grassland or arable. The mineral associated OC (MinOC) fraction was proportionally greater in the subsoil compared to topsoil under all land uses: arable &gt; grassland &gt; woodland. Clay, Fe and Mn availability play a significant role (R&lt;sup&gt;2&lt;/sup&gt;=0.87) in organic carbon storage in the top 1 m of the soil profile.&lt;/p&gt;&lt;p&gt;It is evidently clear from the findings that land use change has a significant effect on the dynamics of the SOC pool at depth, related to litter inputs to the system.&lt;/p&gt;

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