scholarly journals Soil organic carbon in northern Spain (Galicia, Asturias, Cantabria and País Vasco)

2015 ◽  
Vol 5 ◽  
Author(s):  
Elías Luis Calvo ◽  
Francisco Casás Sabarís ◽  
Juan Manuel Galiñanes Costa ◽  
Natividad Matilla Mosquera ◽  
Felipe Macías Vázquez ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Forest Soils ◽  
Agricultural Soils ◽  
Calcareous Soils ◽  
Mean Annual Precipitation ◽  
Moisture Regime ◽  
Organic Carbon Content ◽  
Northern Spain ◽  
Pais Vasco

The soil organic carbon content was analyzed in more than 7 000 soil samples under different land uses, climates and lithologies from northern Spain (Galicia, Asturias, Cantábria y País Vasco). GIS maps (1:50 000) were made of the % SOC and SOC stocks. The % SOC varies according to land use (higher in forest and scrub soils and lower in agricultural soils) and climate, and there is a highly significant correlation between SOC content and mean annual precipitation. There are significant differences between the soils of Galicia/Western Asturias (GA<sub>w</sub>) and those of the rest of the study area (Central and Eastern Asturias, Cantabria and País Vasco) (A<sub>ce</sub>CV), although these are neighbouring regions. In forest and/or scrub soils with a <em>udic</em> soil moisture regime, in GA<sub>w</sub>, the SOC is usually &gt; 7% and the average stocks 260 t ha<sup> -1</sup> (0-30 cm), and &gt;340 t ha<sup>-1</sup> (0-50 cm) in soils with thick organic matter rich horizons (&gt; 40 cm); these values greatly exceed the average contents observed in forest soils from temperate zones. Under similar conditions of vegetation and climate in soils of A<sub>ce</sub>CV the SOC average is 3% and the mean stocks 90-100 t ha<sup>-1</sup> (0-30 cm). The <em>andic</em> character of acid forest soils in GA<sub>w</sub> and the formation of C-Al,Fe complexes are pointed out as the SOC stabilization mechanism, in contrast to the neutral and calcareous soils that predominate in A<sub>ce</sub>CV, where the main species of OC are easily biodegradable.

Physical and chemical protection of soil organic carbon in three agricultural soils with different contents of calcium carbonate

Soil Research ◽  
2000 ◽  
Vol 38 (5) ◽  
pp. 1005 ◽  
Author(s):  
A. Clough ◽  
J. O. Skjemstad
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Organic Material ◽  
Agricultural Soils ◽  
Calcareous Soils ◽  
High Energy ◽  
Organic Carbon Content ◽  
Photo Oxidation ◽  
Active Organic Carbon ◽  
Physical And Chemical

The amount of organic carbon physically protected by entrapment within aggregates and through polyvalent cation–organic matter bridging was determined on non-calcareous and calcareous soils. The composition of organic carbon in whole soils and <53 m soil fractions was determined by 13C NMR analysis. High energy photo-oxidation was carried out on <53 m fractions and results from the NMR spectra showed 17–40% of organic carbon was in a condensed aromatic form, most likely charcoal (char). The concept that organic material remaining after photo-oxidation may be physically protected within aggregates was investigated by treating soils with a mild acid prior to photo-oxidation. More organic material was protected in the calcareous than the non-calcareous soils, regardless of whether the calcium occurred naturally or was an amendment. Acid treatment indicated that the presence of exchangeable calcium reduced losses of organic material upon photo-oxidation by about 7% due to calcium bridging. These results have implications for N fertiliser recommendations based upon organic carbon content. Firstly, calcium does not impact upon degradability of organic material to an extent likely to affect N fertiliser recommendations. Secondly, standard assessment techniques overestimate active organic carbon content in soils with high char content.

scholarly journals Earthworms accelerate rice straw decomposition and maintenance of soil organic carbon dynamics in rice agroecosystems

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9870
Author(s):  
Ke Song ◽  
Lijuan Sun ◽  
Weiguang Lv ◽  
Xianqing Zheng ◽  
Yafei Sun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Agricultural Soils ◽  
Carbon Mineralization ◽  
Basal Respiration ◽  
Organic Carbon Content ◽  
Straw Decomposition ◽  
Soil Basal Respiration ◽  
Short Period

Background To promote straw degradation, we inoculated returned farmland straw with earthworms (Pheretima guillelmi). Increasing the number of earthworms may generally alter soil organic carbon (SOC) dynamics and the biological activity of agricultural soils. Methods We performed soil mesocosm experiments with and without earthworms to assess the decomposition and microbial mineralization of returned straw and soil enzyme activity across different time periods. Results When earthworms were present in soil, the surface residues were completely consumed during the first four weeks, but when earthworms were absent, most of the residues remained on the soil surface after 18 weeks. On day 28, the SOC content was significantly higher in the treatment where both earthworms and residue had been added. The SOC content was lower in the treatment where earthworms but no residue had been added. The organic carbon content in water-stable macroaggregates showed the same trend. During the first 14 weeks, the soil basal respiration was highest in the treatments with both residues and earthworms. From weeks 14 to 18, basal respiration was highest in the treatments with residues but without earthworms. We found a significant positive correlation between soil basal respiration and soil dissolved organic carbon content. Earthworms increased the activity of protease, invertase, urease and alkaline phosphatase enzymes, but decreased β-cellobiohydrolase, β-glucosidase and xylosidase activity, as well as significantly reducing ergosterol content. Conclusion The primary decomposition of exogenous rice residues was mainly performed by earthworms. Over a short period of time, they converted plant carbon into soil carbon and increased SOC. The earthworms played a key role in carbon conversion and stabilization. In the absence of exogenous residues, earthworm activity accelerated the decomposition of original organic carbon in the soil, reduced SOC, and promoted carbon mineralization.

Space-time monitoring of soil organic carbon content across a semi-arid region of Australia

2021 ◽  
Vol 24 ◽  
pp. e00367
Author(s):  
Patrick Filippi ◽  
Stephen R. Cattle ◽  
Matthew J. Pringle ◽  
Thomas F.A. Bishop
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Arid Region ◽  
Space Time ◽  
Organic Carbon Content ◽  
Soil Organic Carbon Content ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Influence of Slope Gradient and Aspect on Soil Organic Carbon Content in the Region of Niš, Serbia

2021 ◽  
Vol 13 (15) ◽  
pp. 8332
Author(s):  
Snežana Jakšić ◽  
Jordana Ninkov ◽  
Stanko Milić ◽  
Jovica Vasin ◽  
Milorad Živanov ◽  
...  
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Slope Aspect ◽  
Available Phosphorus ◽  
Organic Carbon Content ◽  
Slope Gradient ◽  
Phosphorus And Potassium ◽  
Uncultivated Land

Topography-induced microclimate differences determine the local spatial variation of soil characteristics as topographic factors may play the most essential role in changing the climatic pattern. The aim of this study was to investigate the spatial distribution of soil organic carbon (SOC) with respect to the slope gradient and aspect, and to quantify their influence on SOC within different land use/cover classes. The study area is the Region of Niš in Serbia, which is characterized by complex topography with large variability in the spatial distribution of SOC. Soil samples at 0–30 cm and 30–60 cm were collected from different slope gradients and aspects in each of the three land use/cover classes. The results showed that the slope aspect significantly influenced the spatial distribution of SOC in the forest and vineyard soils, where N- and NW-facing soils had the highest level of organic carbon in the topsoil. There were no similar patterns in the uncultivated land. No significant differences were found in the subsoil. Organic carbon content was higher in the topsoil, regardless of the slope of the terrain. The mean SOC content in forest land decreased with increasing slope, but the difference was not statistically significant. In vineyards and uncultivated land, the SOC content was not predominantly determined by the slope gradient. No significant variations across slope gradients were found for all observed soil properties, except for available phosphorus and potassium. A positive correlation was observed between SOC and total nitrogen, clay, silt, and available phosphorus and potassium, while a negative correlation with coarse sand was detected. The slope aspect in relation to different land use/cover classes could provide an important reference for land management strategies in light of sustainable development.

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