Variation in soil strength, bulk density and gravel concentration along a toposequence in Abeokuta, south-western Nigeria

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 643 ◽  
Author(s):  
F. K. Salako ◽  
P. O. Dada ◽  
J. K. Adesodun ◽  
F. A. Olowokere ◽  
I. O. Adekunle
Keyword(s):  
Land Use ◽  
Water Content ◽  
Bulk Density ◽  
Extreme Values ◽  
Soil Depth ◽  
Density Measurement ◽  
Soil Strength ◽  
Slope Position ◽  
Fine Earth ◽  
Wet Season

This study was carried out at Abeokuta, south-western Nigeria, to understand the variation in soil strength, gravel distribution, and bulk density along a toposequence. In 2003, a 120-m transect on a fallowed land was sampled at every 1 m for topsoil bulk density measurement by excavation (3278 cm3 pits), while soil strength was measured at every soil depth increment of 25 mm to 0.50 m depth. Total dry (ρt) and fine earth (<2 mm) (ρf) bulk densities were determined. Soil water content was also determined. Gravel was divided into classes of 2–4, 4–8, 8–16, and >16 mm. In 2006, four 100-m transects were considered; two each on adjacent fallowed and cultivated lands. Soil strength and water content were measured. The fine earth fraction of topsoil ranged from 62 to 90.6%. Gravel in the 2–4 mm class was dominant with a range of 0.8–35.7%. Thus, cores ≥50 mm could be used in the topsoil to obtain reliable estimates of bulk density. Total bulk density (ρt) was reduced by 4–19% when corrected for gravel to obtain ρf. Soil strength of the lower slope was highest in 2003 (1981–4482 kPa) and lowest in 2006 (1546 kPa). In spite of the apparent significant influence of water content on soil strength, the relationship was weakly expressed by regression analysis, as only 35% of variation in soil strength was explained by water content at 0.10–0.15 m soil depth in 2003. No relationship was found in 2006; the cultivated segment had higher soil strength (2045 kPa) than the fallowed segment (1970 kPa) even though the water contents were similar. Also, only the 2–4 mm gravel significantly influenced ρt. Land use, soil depth, and slope position significantly affected soil strength. Root-limiting soil strength (>2000 kPa) would certainly be encountered below 0.20 m soil depth in the wet season irrespective of land use. Management of this gravelly landscape must be based on the heterogeneous nature of soil physical properties along the toposequence, and this could be made effective by grouping the soils according to slope position and taking interest in the few portions of the landscape with extreme values of gravel distribution and high soil strength.

Profile Soil Property Estimation Using a VIS-NIR-EC-Force Probe

2017 ◽  
Vol 60 (3) ◽  
pp. 683-692 ◽  
Author(s):  
Yongjin Cho ◽  
Kenneth A. Sudduth ◽  
Scott T. Drummond
Keyword(s):  
Soil Properties ◽  
Water Content ◽  
Bulk Density ◽  
Soil Property ◽  
Soil Strength ◽  
Reflectance Spectra ◽  
Land Resource ◽  
Strength Data ◽  
Soil Sensors ◽  
Combining Data

Abstract. Combining data collected in-field from multiple soil sensors has the potential to improve the efficiency and accuracy of soil property estimates. Optical diffuse reflectance spectroscopy (DRS) has been used to estimate many important soil properties, such as soil carbon, water content, and texture. Other common soil sensors include penetrometers that measure soil strength and apparent electrical conductivity (ECa) sensors. Previous field research has related these sensor measurements to soil properties such as bulk density, water content, and texture. A commercial instrument that can simultaneously collect reflectance spectra, ECa, and soil strength data is now available. The objective of this research was to relate laboratory-measured soil properties, including bulk density (BD), total organic carbon (TOC), water content (WC), and texture fractions to sensor data from this instrument. At four field sites in mid-Missouri, profile sensor measurements were obtained to 0.9 m depth, followed by collection of soil cores at each site for laboratory measurements. Using only DRS data, BD, TOC, and WC were not well-estimated (R2 = 0.32, 0.67, and 0.40, respectively). Adding ECa and soil strength data provided only a slight improvement in WC estimation (R2 = 0.47) and little to no improvement in BD and TOC estimation. When data were analyzed separately by major land resource area (MLRA), fusion of data from all sensors improved soil texture fraction estimates. The largest improvement compared to reflectance alone was for MLRA 115B, where estimation errors for the various soil properties were reduced by approximately 14% to 26%. This study showed promise for in-field sensor measurement of some soil properties. Additional field data collection and model development are needed for those soil properties for which a combination of data from multiple sensors is required. Keywords: NIR spectroscopy, Precision agriculture, Reflectance spectra, Soil properties, Soil sensing.

Laboratory and field evaluation of five soil water sensors

2004 ◽  
Vol 84 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Q. Huang ◽  
O. O. Akinremi ◽  
R. Sri Rajan ◽  
P. Bullock
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Field Evaluation ◽  
Soil Bulk Density ◽  
Laboratory Evaluation ◽  
Engineering Sciences ◽  
Probe Calibration

Accurate in situ determination of soil water content is important in many fields of agricultural, environmental, hydrological, and engineering sciences. As numerous soil water content sensors are available on the market today, the knowledge of their performance will aid users in the selection of appropriate sensors. The objectives of this study were to evaluate five soil water sensors in the laboratory and to determine if laboratory calibration is appropriate for the field. In this study, the performances of five sensors, including the Profile Probe™ (PP), ThetaProbe™ , Watermark™, Aqua-Tel™, and Aquaterr™ were compared in the laboratory. The PP and ThetaProbe™ were more accurate than the other soil water sensors, reproducing soil water content using factory recommended parameters. However, when PP was installed on a loamy sand in the field, the same soil that was used for the laboratory evaluation, it overestimated field soil water, especially at depth. Another laboratory experiment showed that soil water content readings from the PP were strongly influenced by soil bulk density. The higher the soil bulk density, the greater was the overestimation of soil water content. Two regression parameters, a0 and a1, which are used to convert the apparent dielectric constant to volumetric water content, were found to increase linearly with the soil bulk density in the range of 1.2 to 1.6 Mg m-3. Finally, the PP was calibrated in the field and a good calibration function was obtained with an r2 of 0.87 and RMSE of 2.7%. The values of a0 and a1 obtained in the field were different from factory recommended parameters (a0 = 2.4 versus 1.6 while a1 = 12.5 versus 8.4) and were independent of soil depth, bulk density, and texture. As such, individual field calibration will be necessary to obtain precise and accurate measurement of soil water content with this instrument. Key words: Soil water content, Profile Probe, calibration, soil water content sensor

Use of neutron and gamma radiation meters to estimate bulk density and correct for bias of sampling for water content in a swelling clay soil

Soil Research ◽  
1988 ◽  
Vol 26 (2) ◽  
pp. 261 ◽  
Author(s):  
AS Hodgson
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Gamma Ray ◽  
Clay Soil ◽  
Soil Depth ◽  
Three Dimensional ◽  
Sampling Bias ◽  
Relative Difference ◽  
Undisturbed Soil ◽  
Shrinkage Cracks

Two radiation methods were used to estimate the bulk density of a three-dimensionally swelling grey clay soil used for furrow irrigation at Narrabri, N.S.W. Firstly, gamma ray scattering was calibrated with measurements of wet bulk density derived from undisturbed soil cores. Secondly, a high correlation between neutron counts and gravimetric water content in this soil provided a basis for predicting bulk density corrected for bias in sampling of shrinkage cracks by using a published theoretical model of three-dimensional soil shrinkage. Gamma ray backscattering was poorly correlated with wet bulk density (�w), possibly because dry bulk density and water content are negatively correlated in swelling soil, which restricted �w to a relatively narrow range of values. This technique is therefore not recommended for use in this soil. High correlation (0 82 < r < 0.98, all P < 0.001) between neutron counts and bulk density corrected for three-dimensional shrinkage was found at all soil depths between 0.1 and 1.5 m. A precision of k0.01 Mg m-3 required from three to six samples per mean, depending on soil depth. The mean relative difference between predictions of bulk density from neutron counts compared with independent estimates by the core method was <4.1% at depths below 0.3 m. The recommended procedure is therefore to predict bulk density from neutron counts in order to correct for sampling bias and bulk density effects associated with the neutron attenuation method. The method eliminates the need for additional sampling for bulk density in conjunction with the neutron moisture meter in soils that shrink and swell three-dimensionally. However, the method is not appropriate for detecting differences in bulk density between soils with different structure unless the constants used in the model and the shrinkage behaviour are known for each soil. The latter requirements would usually preclude the technique for this purpose. At low water contents near the permanent wilting point for cotton, neutron escape through shrinkage cracks did not cause problems at depths below 0.3 m. The neutron method should therefore be appropriate for use at depths below 0.3 m in dryland hydrological studies in this soil.

Deriving regional pedotransfer functions to estimate soil bulk density in Austria

2020 ◽  
Vol 71 (4) ◽  
pp. 241-252
Author(s):  
Cecilie Foldal ◽  
Robert Jandl ◽  
Andreas Bohner ◽  
Ambros Berger
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Bulk Density ◽  
Linear Models ◽  
Soil Depth ◽  
Soil Bulk Density ◽  
Pedotransfer Functions ◽  
Undisturbed Soil ◽  
The Impact

Summary Soil bulk density is a required variable for quantifying stocks of elements in soils and is therefore instrumental for the evaluation of land-use related climate change mitigation measures. Our motivation was to derive a set of pedotransfer functions for soil bulk densities usable to accommodate different levels of data availabilities. We derived sets of linear equations for bulk density that are appropriate for different forms of land-use. After introducing uncertainty factors for measured parameters, we ran the linear models repeatedly in a Monte Carlo simulation in order to test the impact of inaccuracy. The reliability of the models was evaluated by a cross-validation. The single best predictor of soil bulk density is the content of soil organic carbon, yielding estimates with an adjusted R2 of approximately 0.5. A slight improvement of the estimate is possible when additionally, soil texture and soil depth are known. Residual analysis advocated the derivation of land-use specific models. Using transformed variables and assessing land-use specific pedotransfer functions, the determination coefficient (adjusted R2) of the multiple linear models ranged from 0.43 in cropland up to 0.65 for grassland soils. Compared to pedotransfer function, from the literature, the performance of the linear modes were similar but more accurate. Taking into account the likely inaccuracies when measuring soil organic carbon, the soil bulk density can be estimated with an accuracy of +/− 9 to 25% depending on land-use. We recommend measuring soil bulk density by standardized sampling of undisturbed soil cores, followed by post-processing of the samples in the lab by internationally harmonized protocols. Our pedotransfer functions are accurately and transparently presented, and derived from well-documented and high-quality soil data sets. We therefore consider them particularly useful in Austria, where the measured values for soil bulk densities are not available.

How tillage systems and cover crops affect soil penetration resistance

2021 ◽  
Author(s):  
Felice Sartori ◽  
Ilaria Piccoli ◽  
Antonio Berti
Keyword(s):  
Water Content ◽  
Soil Texture ◽  
Cover Crops ◽  
Soil Profile ◽  
Transition Period ◽  
Soil Depth ◽  
Soil Layer ◽  
Penetration Resistance ◽  
Soil Strength ◽  
Tillage Systems

&lt;p&gt;Penetration resistance (PR) is one of the most informative parameters to evaluate soil structure, being related to soil texture, compaction, and water content. PR tests are cheaper and more conservative than bulk density analyses, while potentially they can explore a deeper soil layer. On the other side PR is more sensitive to water content variation. Within this context the aim of this study is to evaluate the effects of different tillage systems and soil covers on soil strength, using PR as an indicator.&lt;/p&gt;&lt;p&gt;In this study, 288 PR tests were performed in the 0-80 cm profile, in an 18-plot field experiment considering three levels of tillage (conventional &amp;#8220;CT&amp;#8221;, minimum &amp;#8220;MT&amp;#8221; and no-tillage &amp;#8220;NT&amp;#8221;) combined with three soil covering during winter (bare soil &amp;#8220;BS&amp;#8221;, tillage radish &amp;#8220;TR&amp;#8221; and winter wheat &amp;#8220;WW&amp;#8221;) with two replicates. The experiment, located in northern Italy, had a homogeneous soil texture (silty loam) and it was sampled in late winter, when the gravimetric water content was equal in all the plot and along the soil profile (0.34 m&lt;sup&gt;3&lt;/sup&gt;m&lt;sup&gt;-3&lt;/sup&gt; on average, close to field capacity). A total of 16 tests were taken in each plot with a hand-pushed digital cone penetrometer with a base area of 2 cm&lt;sup&gt;2&lt;/sup&gt; and an apex angle of 30&amp;#176;.&lt;/p&gt;&lt;p&gt;Average PR tended to increase with soil depth observing a growth from 0.25 to 1.53 MPa in the 0-15 cm layer, constant values (1.30 MPa on average) in the following 20 cm-layer, increased value up to an average of 2.87 MPa in 35-55 cm layer and reduced value (2.63 MPa on average) in the deepest layer (60-80 cm).&lt;/p&gt;&lt;p&gt;Considering the tilled layer (0-30 cm), PR was significantly affected by both tillage and soil covering being lower in CT (1.00 MPa) than MT and NT (1.03 MPa on average) and being lower with WW (0.98 MPa) than BS and TR (1.04 MPa on average). Similar results were registered also looking at the whole soil profile with tillage treatments ranked as follows: CT&lt;NT&lt;MT, while for the cover crops WW and BS (1.81 MPa on average) resulted significantly lower than TR (1.93 MPa). The 2 MPa threshold, considered a critical value for plant growth, was exceeded in the 41% of measured points in TR, 38% in WW and in 35% in BS. Most of exceeding values were collected below the tilled layer (below 30 cm depth).&lt;/p&gt;&lt;p&gt;These preliminary results might suggest the need to carefully monitor the soil strength during the transition period between conventional to conservation agriculture. Indeed, it seemed that tillage radish unexpectedly increased the soil PR, that instead could be mitigated in the top layer with WW. Nevertheless, crop yield was not affected by the type of winter covering, despite the high PR observed in the 30-80 cm layer with TR. This could confirm that an important cover crop function is the creation of root channels, defined as &amp;#8220;bio-macropores&amp;#8221;, that can be used as preferential path by subsequent crop roots even in a strongly compacted soil.&lt;/p&gt;

scholarly journals Variations in Soil Water Content, Infiltration and Potential Recharge at Three Sites in a Mediterranean Mountainous Region of Baja California, Mexico

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1844 ◽  
Author(s):  
Francisco Del Toro-Guerrero ◽  
Enrique Vivoni ◽  
Thomas Kretzschmar ◽  
Stephen Bullock Runquist ◽  
Rogelio Vázquez-González
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Baja California ◽  
Soil Depth ◽  
Critical Role ◽  
Soil Conditions ◽  
Wet Season ◽  
Potential Recharge

In this research, we examined temporal variations in soil water content (θ), infiltration patterns, and potential recharge at three sites with different mountain block positions in a semiarid Mediterranean climate in Baja California, Mexico: two located on opposing aspects (south- (SFS) and north-facing slopes (NFS)) and one located in a flat valley. At each site, we measured daily θ between 0.1 and 1 m depths from May 2014 to September 2016 in four hydrological seasons: wet season (winter), dry season (summer) and two transition seasons. The temporal evolution of θ and soil water storage (SWS) shows a strong variability that is associated mainly with high precipitation (P) pulses and soil profile depth at hillslope sites. Results shows that during high-intensity P events sites with opposing aspects reveal an increase of θ at the soil–bedrock interface suggesting lateral subsurface fluxes, while vertical soil infiltration decreases noticeably, signifying the production of surface runoff. We found that the dry soil conditions are reset annually at hillslope sites, and water is not available until the next wet season. Potential recharge occurred only in the winter season with P events greater than 50 mm/month at the SFS site and greater than 120 mm/month at the NFS site, indicating that soil depth and lack of vegetation cover play a critical role in the transport water towards the soil–bedrock interface. We also calculate that, on average, around 9.5% (~34.5 mm) of the accumulated precipitation may contribute to the recharge of the aquifer at the hillslope sites. Information about θ in a mountain block is essential for describing the dynamics and movement of water into the thin soil profile and its relation to potential groundwater recharge.

scholarly journals Estimating Seasonal Changes in Volumetric Soil Water Content at Landscape Scales in a Savanna Ecosystem Using Two-Dimensional Resistivity Profiling

2008 ◽  
Vol 12 (2) ◽  
pp. 1-25 ◽  
Author(s):  
Diana C. Garcia-Montiel ◽  
Michael T. Coe ◽  
Meyr P. Cruz ◽  
Joice N. Ferreira ◽  
Euzebio M. da Silva ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Dry Season ◽  
Ecosystem Structure ◽  
Two Dimensional ◽  
Wet Season ◽  
Short Period ◽  
2D Resistivity

Abstract Water distributed in deep soil reservoirs is an important factor determining the ecosystem structure of water-limited environments, such as the seasonal tropical savannas of South America. In this study a two-dimensional (2D) geoelectrical profiling technique was employed to estimate seasonal dynamics of soil water content to 10-m depth along transects of 275 m in savanna vegetation during the period between 2002 and 2006. Methods were developed to convert resistivity values along these 2D resistivity profiles into volumetric water content (VWC) by soil depth. The 2D resistivity profiles revealed the following soil and aquifer structure characterizing the underground environment: 0–4 m of permanently unsaturated and seasonally droughty soil, less severely dry unsaturated soil at about 4–7 m, nearly permanently saturated soil between 7 and 10 m, mostly impermeable saprolite interspaced with fresh bedrock of parent material at about 10–30 m, and a region of highly conductive water-saturated material at 30 m and below. Considerable spatial variation of these relative depths is clearly demonstrated along the transects. Temporal dynamics in VWC indicate that the active zone of water uptake is predominantly at 0–7 m, and follows the seasonal cycles of precipitation and evapotranspiration. Uptake from below 7 m may have been critical for a short period near the beginning of the rainy season, although the seasonal variations in VWC in the 7–10-m layer are relatively small and lag the surface water recharge for about 6 months. Calculations using a simple 1-box water balance model indicate that average total runoff was 15–25 mm month−1 in the wet season and about 6–9 mm month−1 in the dry season. Modeled ET was about 75–85 mm month−1 in the wet season and 20–25 mm month−1 in the dry season. Variation in basal area and tree density along one transect was positively correlated with VWC of the 0–3-m and 0–7-m soil depths, respectively, during the wettest months. These multitemporal measurements demonstrate that the along-transect spatial differences in soil moisture are quasi-permanent and influence vegetation structure at the scale of tens to hundreds of meters.

The Effect of Soil Strength on the Growth of Young Wheat Plants

1987 ◽  
Vol 14 (6) ◽  
pp. 643 ◽  
Author(s):  
J Masle ◽  
JB Passioura
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Soil Phosphorus ◽  
Soil Strength ◽  
Leaf Expansion ◽  
Wheat Seedlings ◽  
Penetrometer Resistance ◽  
Carbon Supply ◽  
High Soil ◽  
Carbon Demand

Wheat seedlings were grown in soil of various strengths, obtained by changing the bulk density or the water content of the soil. Leaf expansion and transpiration rate were monitored from emergence until the main stem had 5-7 leaves. Leaf area, and shoot and root dry weights, were negatively correlated with soil strength as measured by penetrometer resistance. The growth of roots was less affected than that of shoots. Leaf expansion was reduced before the first leaf was fully expanded. Relative rates of leaf expansion thereafter were consistently lower at high soil strength, although not always significantly. High soil strength also produced substantially smaller stomatal conductances. All effects were the same whether variations of soil strength were brought about by changes in water content or in bulk density. Three possible causes of reduced shoot growth were examined: (1) a limiting supply of nutrients; or (2) of water, because of a restricted root system; or (3) a reduced carbon supply because of a higher carbon demand from the roots, or because of the low stomatal conductance. We conclude that these are all unlikely explanations for the onset of the effects of soil strength, which were independent of soil phosphorus content, of leaf water potential, and of the amount of carbon reserves in the seed. We suggest that growth of the shoot is primarily reduced in response to some hormonal message induced in the roots when they experience high soil strength.

scholarly journals Effects of Land Use Change on the Soil Organic Carbon and Selected Soil Properties in the Sultan Marshes, Turkey

2021 ◽  
Author(s):  
Selma Yaşar Korkanç ◽  
Mustafa Korkanç ◽  
Muhammet Hüseyin Mert ◽  
Abdurrahman Geçili ◽  
Yusuf Serengil
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Properties ◽  
Bulk Density ◽  
Carbon Stock ◽  
Soil Depth ◽  
Aggregate Stability ◽  
Carbon Stocks ◽  
Effects Of Land Use

Abstract This study aims the effects of land use changes on the carbon storage capacity and some soil properties of The Sultan Marshes was partially drained during the middle of the last century and converted to other land uses. Undisturbed soil sampling was performed in different land use types (rangelands, shrubs, marsh, agriculture, and dried lake area) in the wetland area at depths of 0-50 cm, and soil organic carbon (SOC), bulk density, and carbon stocks of soils for each land use type were calculated at 10 cm soil depth levels. Furthermore, disturbed soil samples were taken at two soil depths (0-20 cm and 20-40 cm), and the particle size distribution, pH, electrical conductivity (EC), aggregate stability and dispersion ratio (DR) properties of the soils were analyzed. Data were processed using ANOVA, Duncan’s test, and Pearson’s correlation analysis. The soil properties affected by land use change were SOC, carbon stock, pH, EC, aggregate stability, clay, silt, sand contents, and bulk density. SOC and carbon stocks were high in rangeland, marsh, and shrub land, while they were low in agriculture and drained lake areas. As the soil depth increased, SOC and carbon stock decreased. The organic carbon content of the soils exhibited positive relationships with aggregate stability, clay, and carbon stock, while it showed a negative correlation with bulk density, pH, and DR. The results showed that the drainage and conversion of the wetland caused a significant decrease in the carbon contents of the soils.

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