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 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.

Sorption of Metribuzin and Metolachlor in Alaskan Subarctic Agricultural Soils

Weed Science ◽  
1992 ◽  
Vol 40 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Jeff S. Graham ◽  
Jeffery S. Conn
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Soil Type ◽  
Surface Soil ◽  
Agricultural Soils ◽  
Freundlich Isotherm ◽  
Organic Carbon Content ◽  
Surface Soils ◽  
Adsorption And Desorption ◽  
Equilibration Temperature

Adsorption and desorption of metribuzin and metolachlor were studied for 0- to 15- and 30- to 45-cm soil depths and at 5 and 28 C temperatures for two subarctic Alaskan agricultural soils. Surface soils had five to eight times the organic carbon content of deeper soils and had lower Freundlich isotherm slopes (1/n) for both herbicides. Surface soil Freundlich coefficients (Kf) were affected by both soil type and equilibration temperature, with soil type accounting for greater than 80% of the variation in Kf. Surface soil mean Kfvalues ranged from 1.5 to 2.4 for metribuzin and 4.4 to 9.2 for metolachlor. For soils from the 30- to 45-cm depth, neither soil type nor temperature affected Kf. Isotherm slopes for desorption were less than adsorption, indicating hysteresis. Regressions between desorption Kfand maximum herbicide adsorbed prior to desorption were highly significant with coefficients of determination (r2) between 0.50 and 0.99.

scholarly journals Laboratory, field and airborne spectroscopy for monitoring organic carbon content in agricultural soils

Geoderma ◽  
2008 ◽  
Vol 144 (1-2) ◽  
pp. 395-404 ◽  
Author(s):  
Antoine Stevens ◽  
Bas van Wesemael ◽  
Harm Bartholomeus ◽  
Damien Rosillon ◽  
Bernard Tychon ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Agricultural Soils ◽  
Organic Carbon Content

scholarly journals Soil organic carbon in a toposequence in the semiarid of Paraíba, Brazil

2020 ◽  
Vol 9 (5) ◽  
pp. e164953365
Author(s):  
Cheila Deisy Ferreira ◽  
Francisco Tibério de Alencar Moreira ◽  
Patrícia Carneiro Souto ◽  
Lyanne dos Santos Alencar ◽  
César Henrique Alves Borges
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Soil Analysis ◽  
Superficial Layer ◽  
The Other ◽  
Organic Carbon Content ◽  
Physical And Chemical ◽  
Upper Third

Organic carbon is a sensible indicator to evaluate the environmental quality of the soil. The objective of this study was to evaluate the organic carbon content of the soil in a toposequence in Serra do Teixeira, municipality of Teixeira, PB. Soil samples were collected in the upper third (UT), upper middle third (UMT), lower middle third (LMT) and lower third (LT) on three depths (0-5, 5-10 and 10-20 cm), with five replicates for each depth, resulting in a total of 60 samples. The organic carbon was evaluated using the methodology of Walkey-Black. Physical and chemical soil analysis were also carried out. The highest mean of carbon content was found in the first 5 cm (19.83 g dm-3), significantly differing from the other depths. It was also observed that the mean content of soil organic carbon on LMT was significantly higher than the other thirds, with 19.39 g dm-3. It is concluded that the highest contents of organic carbon are found on the most superficial layer of the soil. The organic carbon content variations found along the toposequence indicates influence of the relief and the anthropic action.

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.

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