Equal-area spline functions applied to a legacy soil database to create weighted-means maps of soil organic carbon at a continental scale

Geoderma ◽  
2012 ◽  
Vol 189-190 ◽  
pp. 153-163 ◽  
Author(s):  
Nathan P. Odgers ◽  
Zamir Libohova ◽  
James A. Thompson
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spline Functions ◽  
Equal Area ◽  
Soil Database ◽  
Continental Scale ◽  
Weighted Means

scholarly journals The Study of Gaining More Detailed Variability Information of Soil Organic Carbon in Surface Soils and Its Significance to Enriching the Existing Soil Database

2020 ◽  
Vol 12 (12) ◽  
pp. 4866
Author(s):  
Zhongqi Zhang ◽  
Jingzhang Li ◽  
Chun-Chih Tsui ◽  
Zueng-Sang Chen
Keyword(s):  
Environmental Management ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Significant Variation ◽  
Soil Mapping ◽  
Digital Soil Mapping ◽  
Actual Distribution ◽  
Equal Area ◽  
Soil Database ◽  
The Mean

To meet the increasing demands of precision agricultural and environmental management, more abundant and accurate information is needed to describe soil organic carbon (SOC) vertical variation. Based on 923 soil profiles (collected at the depths of 0–15, 15–30, 30–60, 60–90, 90–120, and 120–150 cm) in the central area of Changhua County, Taiwan, the distribution curve of the SOC content of each profile was fitted by the equal-area spline model, and it was possible to obtain the SOC content at all depths. Taking the 0–5 cm (L1), 5–10 cm (L2), and 10–15 cm (L3) sub-layers as examples, their SOC contents and stocks were compared to the mean values of the average 5-cm-thick sub-layers (Lm) derived from the value of the 0–15 cm layer. The results indicated that the SOC contents and stocks both reduced with increasing soil depths. The mean SOC contents of L1, L2, and L3 were 22.1, 21.0, and 18.7 g·kg−1, respectively, with significant variation, and the values of L2 and L3 were 5.0% and 15.4% lower than that of L1. Similarly, the mean SOC stocks were 1.29, 1.25, and 1.16 kg·m−2 of the L1, L2, and L3 layers, also with significant variation, and the values of L2 and L3 were 4.0% and 10.1% lower than that of L1. Meanwhile, it was found that the SOC content and stock of Lm were both close to the corresponding values in L2, but were significantly different to that of L1 and L3. Furthermore, the interpolation contours of the SOC contents and stocks in L1, L2, and L3 by digital soil mapping also presented regular variation with increasing soil depths, while the contours of Lm had nearly identical patterns to that of L2. The results demonstrate that the typically used mean SOC contents with certain thicknesses calculated from the sampling layer can only approximately inflect the SOC situation at intermediate depths, but the SOC content in the upper and lower parts within the sampling layer varies greatly. Therefore, the actual distribution of SOC varies gradually depending on the soil depth. This study indicates that the combination of the equal-area spline model and digital soil mapping can greatly enrich the current soil SOC database and provide more abundant and accurate SOC content and stock information for precision agricultural and environmental management based on legacy soil database.

scholarly journals Molecular trade-offs in soil organic carbon composition at continental scale

2020 ◽  
Vol 13 (10) ◽  
pp. 687-692 ◽  
Author(s):  
Steven J. Hall ◽  
Chenglong Ye ◽  
Samantha R. Weintraub ◽  
William C. Hockaday
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Continental Scale ◽  
Trade Offs ◽  
Carbon Composition

scholarly journals A remote sensing adapted approach for soil organic carbon prediction based on the spectrally clustered LUCAS soil database

Geoderma ◽  
2019 ◽  
Vol 353 ◽  
pp. 297-307 ◽  
Author(s):  
Kathrin J. Ward ◽  
Sabine Chabrillat ◽  
Carsten Neumann ◽  
Saskia Foerster
Keyword(s):  
Remote Sensing ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Database

scholarly journals Continental-scale measurement of the soil organic carbon pool with climatic, edaphic, and biotic controls

2006 ◽  
Vol 20 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jonathan G. Wynn ◽  
Michael I. Bird ◽  
Lins Vellen ◽  
Emilie Grand-Clement ◽  
John Carter ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Pool ◽  
Continental Scale ◽  
Organic Carbon Pool ◽  
Biotic Controls

scholarly journals Validating the regional estimates of changes in soil organic carbon by using the data from paired-sites: the case study of Mediterranean arable lands

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Calogero Schillaci ◽  
Sergio Saia ◽  
Aldo Lipani ◽  
Alessia Perego ◽  
Claudio Zaccone ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Depth ◽  
Soil Samples ◽  
Reliable Estimate ◽  
Model Errors ◽  
Paired Data ◽  
Soil Database ◽  
Concentration Changes ◽  
Legacy Data

Abstract Background Legacy data are unique occasions for estimating soil organic carbon (SOC) concentration changes and spatial variability, but their use showed limitations due to the sampling schemes adopted and improvements may be needed in the analysis methodologies. When SOC changes is estimated with legacy data, the use of soil samples collected in different plots (i.e., non-paired data) may lead to biased results. In the present work, N = 302 georeferenced soil samples were selected from a regional (Sicily, south of Italy) soil database. An operational sampling approach was developed to spot SOC concentration changes from 1994 to 2017 in the same plots at the 0–30 cm soil depth and tested. Results The measurements were conducted after computing the minimum number of samples needed to have a reliable estimate of SOC variation after 23 years. By applying an effect size based methodology, 30 out of 302 sites were resampled in 2017 to achieve a power of 80%, and an α = 0.05. A Wilcoxon test applied to the variation of SOC from 1994 to 2017 suggested that there was not a statistical difference in SOC concentration after 23 years (Z = − 0.556; 2-tailed asymptotic significance = 0.578). In particular, only 40% of resampled sites showed a higher SOC concentration than in 2017. Conclusions This finding contrasts with a previous SOC concentration increase that was found in 2008 (75.8% increase when estimated as differences of 2 models built with non-paired data), when compared to 1994 observed data (Z = − 9.119; 2-tailed asymptotic significance < 0.001). This suggests that the use of legacy data to estimate SOC concentration dynamics requires soil resampling in the same locations to overcome the stochastic model errors. Further experiment is needed to identify the percentage of the sites to resample in order to align two legacy datasets in the same area.

scholarly journals Large-scale controls of soil organic carbon in (sub)tropical soils

2020 ◽  
Author(s):  
Sophie F. von Fromm ◽  
Alison M. Hoyt ◽  
Asmeret Asefaw Berhe ◽  
Keith D. Shepherd ◽  
Tor-Gunnar Vågen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Large Scale ◽  
Experimental Studies ◽  
Clay Content ◽  
Carbon Stocks ◽  
Sub Saharan Africa ◽  
Mean Annual Precipitation ◽  
Tropical Regions ◽  
Continental Scale

&lt;p&gt;Soil organic carbon (SOC) is a key component of terrestrial ecosystems. Experimental studies have shown that soil texture and geochemistry have a strong effect on carbon stocks. However, those findings primarily rely on data from temperate regions or use model approaches that are often based on limited data from tropical and sub-tropical regions.&lt;/p&gt;&lt;p&gt;Here, we evaluate the controls on soil carbon stocks in Africa, using a dataset of 1,580 samples. These were collected across Sub-Saharan Africa (SSA) within the framework of the Africa Soil Information Service (AfSIS) project, which was built on the well-established Land Degradation Surveillance Framework (LDSF). Samples were taken from two depths (0&amp;#8211;20 cm and 20&amp;#8211;50 cm) at 46 LDSF sites that were stratified according to Koeppen-Geiger climate zones. The different pH-values, clay content, exchangeable cations and extractable elements across various soils of the different climatic zones (i.e. from arid to humid (sub)tropical) allow us to identify different soil and climate parameters that best explain SOC variance across SSA.&lt;/p&gt;&lt;p&gt;We tested if these SOC predictors differed across climatological conditions, using the ratio of potential evapotranspiration (PET) to mean annual precipitation (MAP) as indicator. For water-limited regions (PET/MAP &gt; 1), the best predictors were climatic variables, likely because of their effect on the quantity of carbon inputs. Geochemistry dominated SOC storage in energy-limited systems (PET/MAP &lt; 1), reflecting its effect on carbon protection. On a continental scale, climate (e.g. PET) is key to predicting SOC content in topsoil, whereas geochemistry, particularly iron-oxyhydroxides and aluminum-oxides, is more important in subsoil. Clay content had little influence on SOC at both depths. These findings contribute to an improved understanding of the controls on SOC stocks in tropical and sub-tropical regions.&lt;/p&gt;

scholarly journals Surface Soil Organic Carbon Sequestration Under Post Agricultural Grasslands Offset by Net Loss at Depth

2021 ◽  
Author(s):  
Yi Yang ◽  
Terrance Loecke ◽  
Johanness Knops
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Surface Soil ◽  
C Sequestration ◽  
The United States ◽  
Soil Profiles ◽  
Continental Scale ◽  
C Dynamics ◽  
Subsurface Soil ◽  
Soc Stock

Abstract Post agricultural grasslands are considered to accumulate soil organic carbon (SOC) after cultivation cessation. The Conservation Reserve Program (CRP) in the U.S. is a wide scale, covering approximately 8.9 Mha as of 2020, example of row-crop to grassland conversion. To date, SOC sequestration rates, and potential, in CRP has mostly been evaluated at local scales and focused on the surface 20–30 cm of the soil profile. Thus, we lack knowledge of C sequestration rates in CRP lands on a continental scale and of C dynamics in the subsurface soil after agricultural cessation. The Rapid Carbon Assessment (RaCA) project is the most recent effort by the United States Department of Agriculture (USDA) to systematically quantify C stock in the 0-100 cm soil profiles across the conterminous US. Here we analyze data from RaCA to evaluate the C stocks of the CRP on a continental scale of both surface and subsurface soil. We found there was no difference in SOC stock between croplands and CRP lands when comparing the 0-100 cm soil profiles, which indicates that the C sequestration in CRP lands is insignificant overall. We did find that SOC accumulated in the surface soil (0–5 cm) in CRP lands. However, theses C gains in surface (0–5 cm) soil were offset by the lower SOC stock in the subsurface (30–100 cm) of the CRP. We also found that the C: N ratio in the subsurface soil in CRP lands is lower than that of croplands, indicating a lack of labile organic matter inputs in the subsoil. Whether the lower SOC in the subsurface of CRP is caused by legacy effects or is a result of C losses needs to be verified by long-term repeated sampling in both surface and subsurface soil. This analysis highlights the importance of examining C dynamics in subsurface soil after agricultural cessation to accurately measure and improve C sequestration rates in CRP lands.

scholarly journals Continental-scale controls on soil organic carbon across sub-Saharan Africa

SOIL ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 305-332
Author(s):  
Sophie F. von Fromm ◽  
Alison M. Hoyt ◽  
Markus Lange ◽  
Gifty E. Acquah ◽  
Ermias Aynekulu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Land Cover ◽  
Soil Texture ◽  
Sub Saharan Africa ◽  
Continental Scale ◽  
Weathered Soils ◽  
Exchangeable Ca ◽  
Extractable Metals ◽  
Sub Saharan

Abstract. Soil organic carbon (SOC) stabilization and destabilization has been studied intensively. Yet, the factors which control SOC content across scales remain unclear. Earlier studies demonstrated that soil texture and geochemistry strongly affect SOC content. However, those findings primarily rely on data from temperate regions where soil mineralogy, weathering status and climatic conditions generally differ from tropical and subtropical regions. We investigated soil properties and climate variables influencing SOC concentrations across sub-Saharan Africa. A total of 1601 samples were analyzed, collected from two depths (0–20 and 20–50 cm) from 17 countries as part of the Africa Soil Information Service project (AfSIS). The data set spans arid to humid climates and includes soils with a wide range of pH values, weathering status, soil texture, exchangeable cations, extractable metals and land cover types. The most important SOC predictors were identified by linear mixed-effects models, regression trees and random forest models. Our results indicate that geochemical properties, mainly oxalate-extractable metals (Al and Fe) and exchangeable Ca, are equally important compared to climatic variables (mean annual temperature and aridity index). Together, they explain approximately two-thirds of SOC variation across sub-Saharan Africa. Oxalate-extractable metals were most important in wet regions with acidic and highly weathered soils, whereas exchangeable Ca was more important in alkaline and less weathered soils in drier regions. In contrast, land cover and soil texture were not significant SOC predictors on this large scale. Our findings indicate that key factors controlling SOC across sub-Saharan Africa are broadly similar to those in temperate regions, despite differences in soil development history.

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