scholarly journals PEDO-TRANSFER FUNCTIONS FOR ESTIMATING SOIL BULK DENSITY IN CENTRAL AMAZONIA

2015 ◽  
Vol 39 (2) ◽  
pp. 397-407 ◽  
Author(s):  
Henrique Seixas Barros ◽  
Philip Martin Fearnside
Keyword(s):  
Bulk Density ◽  
Transfer Functions ◽  
Clay Content ◽  
Information Criterion ◽  
Soil Bulk Density ◽  
Coefficient Of Determination ◽  
Permanent Plots ◽  
Amazon Forest ◽  
Soil C ◽  
C Stocks

Under field conditions in the Amazon forest, soil bulk density is difficult to measure. Rigorous methodological criteria must be applied to obtain reliable inventories of C stocks and soil nutrients, making this process expensive and sometimes unfeasible. This study aimed to generate models to estimate soil bulk density based on parameters that can be easily and reliably measured in the field and that are available in many soil-related inventories. Stepwise regression models to predict bulk density were developed using data on soil C content, clay content and pH in water from 140 permanent plots in terra firme (upland) forests near Manaus, Amazonas State, Brazil. The model results were interpreted according to the coefficient of determination (R2) and Akaike information criterion (AIC) and were validated with a dataset consisting of 125 plots different from those used to generate the models. The model with best performance in estimating soil bulk density under the conditions of this study included clay content and pH in water as independent variables and had R2 = 0.73 and AIC = -250.29. The performance of this model for predicting soil density was compared with that of models from the literature. The results showed that the locally calibrated equation was the most accurate for estimating soil bulk density for upland forests in the Manaus region.

Changes in soil carbon and soil nitrogen after tree clearing in the semi-arid rangelands of Queensland

2005 ◽  
Vol 53 (7) ◽  
pp. 639 ◽  
Author(s):  
B. P. Harms ◽  
R. C. Dalal ◽  
A. P. Cramp
Keyword(s):  
Soil Carbon ◽  
Soil Depth ◽  
Woody Debris ◽  
Soil Phosphorus ◽  
Basal Area ◽  
Clay Content ◽  
Strongly Correlated ◽  
Soil N ◽  
Soil C ◽  
C Stocks

Changes in soil carbon (C) and nitrogen (N) stocks following tree clearing were estimated at 32 rangeland sites in central and southern Queensland by using paired-site sampling. When corrected for soil bulk-density differences at each site, average soil C across all sites decreased after tree clearing by 8.0% for 0–0.3-m soil depth, and by 5.4% for 0–1.0-m depth; there were corresponding declines in soil C of 2.5 and 3.5tha–1, respectively. Mean soil C stocks (excluding surface litter, extractable roots and coarse charcoal) at uncleared sites were 29.5tha–1 for 0–0.3-m soil depth, and 62.5tha–1 for 0–1.0-m depth. Mean soil C stocks (0–0.3m) were 41% of the mean total C for the soil–plant system (soil + litter/woody debris + stand biomass) at uncleared sites. Soil C decline (0–0.3m) accounted for approximately 7% of the average total C lost because of land clearing across all sites. Soil C stocks at uncleared sites were correlated with tree basal area, clay content and soil phosphorus (P) content. Changes in soil C after tree clearing were strongly correlated to initial soil C contents at the uncleared sites, and were associated with particular vegetation groups and soil types. Changes in soil N were strongly correlated with changes in soil C; however, the average change in soil N across all sites was not significant. Given the size of the C and N pools in rangeland soils, the factors that influence soil C and soil N dynamics in rangeland systems need to be better understood for the effective management of C stocks in these soils.

scholarly journals Spoil characteristics under five years old native woody plantations and unplanted dump in dry tropical environment, India.

2017 ◽  
Vol 6 (11) ◽  
pp. 1763
Author(s):  
Anand Narain Singh
Keyword(s):  
Bulk Density ◽  
Tectona Grandis ◽  
Soil Bulk Density ◽  
Substantial Improvement ◽  
Exchangeable Cations ◽  
Mine Spoil ◽  
Chemical Characteristics ◽  
Dendrocalamus Strictus ◽  
Soil C ◽  
Mine Spoils

Present study was conducted to investigate spoil characteristics under 5-yr old high-density plantations of three native trees (Albizia lebbeck A. procera and Tectona grandis) and one fast growing woody grass (Dendrocalamus strictus) species on coal mine spoils and same age unplanted mine spoil dump at the same area. We examined physical characters such as soil bulk density, water holding capacity, soil texture (sand, clay and silt) and chemical characters such as pH, total nutrients (C, N and P) and exchangeable cations (Ca, Mg, K and Na) in chronosequence of spoil depth (0-50 cm) at 10 cm interval under planted stand of each selected species and unplanted dump. A significant effect of plantations on physico-chemical characteristics (except soil bulk density) of mine spoils was found. Among species, A. lebbeck exhibited substantial improvement in mine spoil soils followed by D. strictus, A. procera and T. grandis plantation. Although, chemical characteristics especially total concentrations of soil C, N and P and their ratios were significantly different due to species and spoil depth, indicating plantations of all species have abilities to improve soil chemical qualities at young stage of establishment. Compared to unplanted dump, plantation of A. lebbeck showed highest concentrations of total nutrients (C, N and P) and exchangeable cations with respect to spoil depth followed by D. strictus, A. procera and T. grandis, which confirms that some species have suitable qualities for the modification of spoil characteristics during rehabilitation process.

scholarly journals Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired <sup>14</sup>C analysis

2015 ◽  
Vol 12 (2) ◽  
pp. 891-932 ◽  
Author(s):  
S. J. Hall ◽  
G. McNicol ◽  
T. Natake ◽  
W. L. Silver
Keyword(s):  
Tropical Forests ◽  
Clay Content ◽  
Multiple Time ◽  
Luquillo Experimental Forest ◽  
Reactive Metal ◽  
Near Surface ◽  
Soil C ◽  
C Stocks ◽  
Pool Model ◽  
Topographic Positions

Abstract. It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised the large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (74 ± 4%) was rapid (9 to 29 years, mean and SE 20 ± 2 years) in 25 of 30 soil samples across surface horizons (0–10 and 10–20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial – millennial turnover was much less abundant (26%), even at 10–20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral associated C over decadal scales. Steady-state inputs of mineral-associated C were similar among the three topographic positions, and could represent 10–30% of annual litterfall production (estimated by doubling aboveground litterfall). Observed trends in mineral-associated Δ14C over time could not be fit using the single pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic constrained two-pool model. The large C fluxes in surface and near-surface soils implied by our data suggest that other studies using single-pool Δ14C models of mineral-associated C dynamics, unconstrained by multiple time points, may have systematically underestimated C turnover.

scholarly journals Simulation of soil carbon dynamics in Australia under a framework that better connects spatially explicit data with Rᴏᴛʜ C

2020 ◽  
Author(s):  
Juhwan Lee ◽  
Raphael A. Viscarra Rossel ◽  
Zhongkui Luo ◽  
Ying Ping Wang
Keyword(s):  
C:N Ratio ◽  
Clay Content ◽  
Spatially Explicit ◽  
Natural Environments ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Soil C ◽  
Continental Scale ◽  
C Stocks

Abstract. We simulated soil organic carbon (C) dynamics across Australia with the Rothamsted carbon model (Rᴏᴛʜ C) under a framework that connects new spatially-explicit soil measurements and data with the model. Doing so helped to bridge the disconnection that exists between datasets used to inform the model and the processes that it depicts. Under this framework, we compiled continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated Rᴏᴛʜ C and run simulations to predict the baseline soil organic C stocks and composition in the 0–0.3 m layer at 4,043 sites in cropping, modified grazing, native grazing, and natural environments across Australia. The Rᴏᴛʜ C model uses measured C fractions, the particulate, humus, and resistant organic C (POC, HOC and ROC, respectively) to represent the three main C pools in its structure. The model explained 97–98 % of the variation in measured total organic C in soils under cropping and grazing, and 65 % in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to predict the potential for C accumulation in a 100-year simulation. With an annual increase of 1 Mg C ha−1 in C inputs, the model predicted a potential soil C increase of 13.58 (interquartile range 12.19–15.80), 14.21 (12.38–16.03), and 15.57 (12.07–17.82) Mg C ha−1 under cropping, modified grazing and native grazing, and 3.52 (3.15–4.09) Mg C ha−1 under natural environments. Soils under native grazing were the most potentially vulnerable to C decomposition and loss, while soils under natural environments were the least vulnerable. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C:N ratio, and cropping were the most important controls on POC change. Clay content and climate were dominant controls on HOC change. Consistent and explicit soil organic C simulations improve confidence in the model's predictions, contributing to the development of sustainable soil management under global change.

scholarly journals The roots of blue carbon: responses of mangrove stilt roots to variation in soil bulk density

2019 ◽  
Vol 15 (4) ◽  
pp. 20180866 ◽  
Author(s):  
Anne Ola ◽  
Arnault R. G. Gauthier ◽  
Yanmei Xiong ◽  
Catherine E. Lovelock
Keyword(s):  
Bulk Density ◽  
Primary Root ◽  
C Sequestration ◽  
Soil Bulk Density ◽  
Structural Features ◽  
Root Diameter ◽  
Rhizophora Stylosa ◽  
C Stocks ◽  
Aerial Roots ◽  
Below Ground

Mangroves harbour large soil organic carbon (C) pools. These C stocks are attributed to the production and slow decomposition of the below-ground biomass. Novel in-growth containers were used to assess the effect of soil bulk density (BD: 0.4, 0.8 and 1.2 g cm −3 ) on morphological, anatomical and chemical traits of the below-ground fraction of aerial roots of the mangrove Rhizophora stylosa . Dense soils increased total root biomass and primary root diameter, while the primary root length decreased. Furthermore, high soil BD reduced aerenchyma lacunae and led to the formation of structural features such as fibrous strands. These morphological and anatomical changes were not reflected in tissue chemistry, with lignin levels averaging 17.0 ± 0.6%, although roots grown in high BD had higher nitrogen levels. This likely affects decomposition rates. Thus, variation in soil BD has major implications for C sequestration in Rhizophora- dominated mangroves.

scholarly journals Water retention of the loess-derived Luvisols with lamellic illuvial horizon in the Trzebnica Hills (SW Poland)

2014 ◽  
Vol 65 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Bartłomiej Glina ◽  
Jarosław Waroszewski ◽  
Cezary Kabała
Keyword(s):  
Bulk Density ◽  
Water Retention ◽  
Clay Content ◽  
Field Work ◽  
Soil Bulk Density ◽  
Illuvial Horizon ◽  
Water Properties ◽  
Clayey Silt ◽  
Sw Poland ◽  
Humus Horizons

Abstract The aim of work was to characterize the water retention in the silt-textured Luvisols with lamellic illuvial horizon (argic) that occur in the loess covered northern part of the Silesian Lowland. Soil pits were localized on the Trzebnica Hills near the villages: Machnice (profile 1), Skarszyn (profile 2) and Zaprężyn (profile 3 and 4). Profiles Machnice 1 and Skarszyn 2 were situated in the upper parts of the hills covered with beech stands with an admixture of oak, linden and maple. Profiles Zaprężyn 3 and 4 were situated in the central and lower parts of the arable slope. During the field work conducted in April 2011, 29 soil samples were collected for texture, bulk density and water properties analysis. The soils under study were characterized by texture of silt loam with lower clay content in humus horizons (.loamy silt. according to Polish classification), and higher clay content (.clayey silt.) in the illuvial and subsoil horizons. The texture of all examined profiles was dominated by the „loess“ fractions. Variable abundance of the massive lamellae causes variations in water properties of the illuvial (sub-)horizons. It was found that lamellic illuvial horizons in the loess-derived Luvisols have higher field water capacity than the homogenous illuvial horizons, apart of the clay content. There was no apparent effect of the horizon kind (homogeneous versus lamellic) on the soil bulk density. These properties mainly depended on the total clay content in a particular horizon (sub-horizon).

Measurements and simulations of compaction effects on the least limiting water range of a no-till Oxisol

Soil Research ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 62 ◽  
Author(s):  
Renato P. de Lima ◽  
Thomas Keller ◽  
Neyde B. F. Giarola ◽  
Cassio A. Tormena ◽  
Anderson R. da Silva ◽  
...  
Keyword(s):  
Transfer Function ◽  
Bulk Density ◽  
Transfer Functions ◽  
Sandy Loam ◽  
Soil Bulk Density ◽  
Model Soil ◽  
No Till ◽  
Before And After ◽  
Least Limiting Water Range

No-till has many environmental advantages, but concerns are growing about vehicle-induced topsoil compaction limiting crop growth. We performed a wheeling experiment in a long-term no-till field on an Oxisol with sandy loam texture. The objectives were to measure changes in soil bulk density and corresponding impacts on the least limiting water range (LLWR) due to passage of a maize harvester, and to compare bulk density and LLWR measurements with values simulated using the SoilFlex-LLWR soil compaction model. Soil cores were sampled before and after wheeling, for bulk density measurements and to determine LLWR. Simulated increase in bulk density due to vehicle wheeling agreed well with measurements. However, simulated LLWR and its decrease with compaction were inaccurate. This was ascribed to the pedo-transfer function used in SoilFlex-LLWR to estimate LLWR parameters, which was developed based on data from conventionally tilled sugarcane fields, whereas our site was a long-term no-till soil under a wheat/soybean–maize/black oats rotation. Our measurements showed that LLWR was strongly restricted by soil penetration resistance, which was not captured by the pedo-transfer function incorporated in SoilFlex-LLWR. For better prediction of LLWR, we recommend development of specific pedo-transfer functions or of mechanistic models that can be incorporated in SoilFlex-LLWR.

scholarly journals Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired <sup>14</sup>C analysis

2015 ◽  
Vol 12 (8) ◽  
pp. 2471-2487 ◽  
Author(s):  
S. J Hall ◽  
G. McNicol ◽  
T. Natake ◽  
W. L. Silver
Keyword(s):  
Tropical Forests ◽  
Clay Content ◽  
Litter Production ◽  
Luquillo Experimental Forest ◽  
Reactive Metal ◽  
Near Surface ◽  
Soil C ◽  
C Stocks ◽  
Pool Model ◽  
Topographic Positions

Abstract. It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised the large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (66 ± 2%) was rapid (11 to 26 years; mean and SE: 18 ± 3 years) in 25 of 30 soil samples across surface horizons (0–10 and 10–20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial–millennial turnover was typically much less abundant (34 ± 3%), even at 10–20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral-associated C over decadal scales. Steady-state inputs of mineral-associated C were statistically similar among the three topographic positions, and could represent 10–25% of annual litter production. Observed trends in mineral-associated Δ14C over time could not be fit using the single-pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic two-pool model. The large C fluxes in surface and near-surface soils documented here are supported by findings from paired 14C studies in other types of ecosystems, and suggest that most mineral-associated C cycles relatively rapidly (decadal scales) across ecosystems that span a broad range of state factors.

scholarly journals Estimation of precompression stress in an Ultisol cultivated with sugarcane

2019 ◽  
Vol 23 (5) ◽  
pp. 336-340 ◽  
Author(s):  
Pericles M. B. Mendes ◽  
Mário M. Rolim ◽  
Renato P. de Lima ◽  
Elvira M. R. Pedrosa ◽  
Uilka E. Tavares ◽  
...  
Keyword(s):  
Bulk Density ◽  
Transfer Functions ◽  
Soil Management ◽  
Soil Bulk Density ◽  
Multiple Regression Model ◽  
Physical Parameters ◽  
Compression Tests ◽  
Undisturbed Soil ◽  
Precompression Stress ◽  
The Impact

ABSTRACT Compressive soil properties are typically used for the understanding of compaction process. As an alternative to laboratory tests, pedo-transfer functions have been used to estimate the mechanical behaviour of soil as a function of soil physical parameters. The impact of soil bulk density (BD) and gravimetric water content (w) was examined on soil strength and pedo-transfer functions were proposed to predict the precompression stress (σp) in an Ultisol cultivated with sugarcane. Undisturbed soil cores were sampled at the depths of 0-0.20 and 0.20-0.40 m, subjected to different water contents, and subsequently, compression tests were performed to determine σp. The data were subjected to analysis of variance and regression analysis. Bulk density and w affected σp positively and negatively, respectively. Approximately 70% of the variation of the σp could be explained as a function of BD and w through an accessible multiple regression model. Comparisons with other pedo-transfer functions showed that estimates of σp may be rather sensitive to soil management and textural classes. Variations imposed by soil management and cohesive character into depth suggest that independent models should be considered to characterise compressive behaviour of soil by horizon or layer.

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