Relationships between 137Cs and soil organic carbon (SOC) in cultivated and never-cultivated soils: An Australian example

Post agricultural development of traditionally intensively cultivated high fertility soils is a relevant question in surroundings of towns affected by urban sprawl, where extent areas of former cultivated soils are converted into residential, industrial or infrastructural surfaces. Part of these areas will covered by artificially sealed soils, but always extent areas remain for green areas, managed with different intensity, which allows recharge of soil organic carbon stocks and soil regeneration processes. In our study agricultural and post agricultural soils were sampled in a Chernozemic landscape affected by urbanization processes. Besides of other regeneration processes, concerning to the improvement of soil structure, we found that soil organic carbon stocks in the 0-30 cm soil layer are significantly higher in post agricultural soils (9.4&#177;0.5 kg&#183;m-2) as in ploughed (6.4&#177;0.8 kg&#183;m-2) or in ploughed plus irrigated (5.6&#177;0.7 kg&#183;m-2) profiles. The difference was found to be significant not only until the depth of the cultivated layer (30 cm), but until the sampled 70 cm depth throughout (17.8&#177;0.9; 10.8&#177;3.3 and 10.6&#177;2.7 kg&#183;m-2 respectively). Our results point on the high carbon recovery potential of suburban areas converted from fertile cultivated soils.

Download Full-text

Soil organic carbon and nitrogen losses due to soil erosion and cropping in a sloping terrace landscape

Soil Research ◽

10.1071/sr14151 ◽

2015 ◽

Vol 53 (1) ◽

pp. 87 ◽

Cited By ~ 23

Author(s):

J. H. Zhang ◽

Y. Wang ◽

F. C. Li

Keyword(s):

Soil Erosion ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Surface Soil ◽

Soil Horizon ◽

Small Scale ◽

Cultivated Land ◽

N Losses ◽

Uncultivated Land ◽

Cultivated Soils

Effects of soil erosion and cropping on soil organic carbon (SOC) stocks need to be addressed to better understand the processes of SOC loss following the conversion of natural ecosystems to agriculture. The aims of the present study were to: (1) understand the mechanism of SOC and total nitrogen (TN) losses in a small-scale agricultural landscape with sloping terraces; and (2) quantitatively assess vertical changes in SOC and TN of soil profiles at specific landscape positions and the lateral distribution of SOC and TN in areas with different soil erosion and deposition rates. Soil samples from cultivated land were collected at 5-m intervals along toposequences in different parts of hilly areas of the Sichuan Basin, China; uncultivated land was used as a reference for 137Cs, SOC and TN. The profile shape of SOC and total N depth distribution was markedly different between cultivated and uncultivated soils, with differences in descriptive coefficients of 2.1–3.4- and 2.0–3.2-fold for a, 1.2–2.2- and 1.0–1.8-fold for b, respectively, in the equation y = –aln(x) + b, where y is the depth SOC or TN concentration and x is the depth from the soil surface. SOC and TN concentrations in the surface soil horizon were significantly higher on uncultivated land (17.5 g kg–1) than on cultivated land (7.06–9.81 g kg–1). In particular, the 0–5 cm surface layer of uncultivated soils had 1.3-, 1.7-, and 2.3-fold higher SOC concentrations than that of the depositional, weak erosional and strong erosional areas, respectively, in cultivated soils. However, there were no significant differences in SOC and TN concentrations in subsoil layers between cultivated and uncultivated lands, suggesting that cropping is one of the factors causing SOC and N losses. SOC and TN inventories exhibited an increasing trend from the upper to toe proportions of the cultivated toposequences. In all the cultivated soils, SOC and TN concentrations of the surface soil horizon and inventories of SOC and TN were closely associated with 137Cs inventories (P < 0.001, P < 0.01, P < 0.0001 and P < 0.0001, respectively), suggesting that soil erosion has an important impact on SOC and TN dynamics in the cultivated landscape. The results of this study suggest that soil erosion and cropping result in SOC and N losses, and that soil erosion contributes to marked variations in SOC and N distribution along the slope transect within individual sloping terraces, as well as in the entire landscape.

Download Full-text

Spatial changes in soil organic carbon density and storage of cultivated soils in China from 1980 to 2000

Global Biogeochemical Cycles ◽

10.1029/2008gb003428 ◽

2009 ◽

Vol 23 (2) ◽

pp. n/a-n/a ◽

Cited By ~ 45

Author(s):

Yanyan Yu ◽

Zhengtang Guo ◽

Haibin Wu ◽

Julia A. Kahmann ◽

Frank Oldfield

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Density ◽

Spatial Changes ◽

Soil Organic Carbon Density ◽

And Storage ◽

Cultivated Soils

Download Full-text

Effect of lime (CaCO3) application on soil structural stability of a red earth

Soil Research ◽

10.1071/s97054 ◽

1998 ◽

Vol 36 (1) ◽

pp. 73 ◽

Cited By ~ 33

Author(s):

K. Y. Chan ◽

D. P. Heenan

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Structural Stability ◽

Wagga Wagga ◽

Lime Treatment ◽

Temporary Reduction ◽

Red Earth ◽

Lime Application ◽

Soil Structural Stability ◽

Cultivated Soils

Changes in soil structural stability as a result of lime application (1·5 t/ha) were monitored over 3 years in a red earth with contrasting initial pH, organic carbon, and structural stability conditions at Wagga Wagga, NSW. The lime was applied to the surface of the direct drilled-soil without any incorporation, but in the case of the cultivated soils, the lime was incorporated into the top 10 cm by scarifying. After liming, an initial temporary reduction in macroaggregate (>2 µm) stability was detected in the immediate surface (0-2·5 cm) of the direct-drilled soil where the highest increases in pH, losses in soil organic carbon, and increases in microbial biomass were also observed. The decrease in structural stability was attributed to lime-induced increases in biological decomposition and the resulting soil organic carbon losses. Subsequent samplings did not detect any difference in either macro- or micro- (<50 µm) aggregate stability of this soil as a result of lime treatment. In contrast, for the 2 cultivated soils which had lower initial structural stability and organic carbon levels, a decline in stability was not observed. Instead, significant increases in macroaggregate and microaggregate stability were detected 1·5 years after lime application. By the end of 3 years, macroaggregate stability of the limed cultivated soils approached that of the direct-drilled soil. The improvement in structural stability extended to 7·5 cm depth 3 years after lime application. Wet-sieving experiments using prolonged periods of shaking indicated enhanced stability of the water-stable aggregates of the limed cultivated soils but not the direct-drilled soils.

Download Full-text

Does agricultural practices impact the quantity and the forms of organic carbon stored in cultivated soils of the Senegal groundnut basin? A Rock-Eval approach

10.5194/egusphere-egu2020-11229 ◽

2020 ◽

Author(s):

Oscar Pascal Malou ◽

David Sebag ◽

Patricia Moulin ◽

Tiphaine Chevallier ◽

Yacine Badiane Ndour ◽

...

Keyword(s):

Thermal Analysis ◽

Standard Deviation ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Agricultural Practices ◽

Sandy Soils ◽

Organic Wastes ◽

Rock Eval ◽

Cultivated Soils

Soil organic carbon (SOC) is a key element in the functioning of agrosystems. It ensures soil quality and productivity of cultivated systems in the Sahelian region. This study uses Rock-Eval pyrolysis to examine how cultural practices impact SOC quantity and quality of cultivated sandy soils in the Senegal groundnut basin. Such thermal analysis method provides cost-effective information on SOC thermal stability that has been shown to be qualitatively related to SOC biogeochemical stability. Soils were sampled within 2 villages agricultural plots representative of local agricultural systems and for local preserved areas. Total SOC concentrations ranged from 1.8 to 18.5 g.kg-1 soil (mean &#177; standard deviation: 5.6 &#177; 0.4 g.kg-1 soil) in the surface layer (0-10 cm) and from 1.5 to 11.3 g.kg-1 soil (mean &#177; standard deviation: 3.3 &#177; 0.2 g.kg-1 soil) in 10-30 cm deep layer. SOC of cultivated soils significantly (p-value < 0.0001) decreased according to treatments in the following order: +organic wastes > +manure > +millet residues > no input. Our results show that the quantity and the quality of SOC are linked to each other and both depend on land-use and agricultural practices, especially the nature of organic inputs. This correlation is very strong in the tree plantation (R&#178; = 0.98) and in the protected shrubby savanna (R&#178; = 0.97). It remains important for cultivated soils receiving organic wastes (R&#178; = 0.82), manure (R&#178; > 0.75), or millet residues (R2 = 0.91) but it&#8217;s no more significant in no-input situations. The Rock-Eval based indexes were depicted in a I/R diagram that illustrate the level of SOC stabilization and plotted against comparable results from literature. The Senegalese sandy soils have thermal signatures showing an inversion of the I and the R indexes compared to data from the literature and highlighting SOC stabilization as a function of soil depth. Indeed, the studied soils were characterized by a more abundant refractory pool (A5 which ranged from 7.7 to 21.3 % in 0-10 cm layer and from 12.5 to 24.3 % in 10-30 cm, respectively) compared to other tropical soils. The SOC in these sandy soils while positively affected by organic inputs is dominated by labile forms that mineralize quickly which is excellent for the needs of productivity of these agrosystems but not for mitigation of climate change.Keywords: Soil organic carbon; Organic inputs; Thermal analysis; Agrosystems; West Africa

Download Full-text