Effects Of Soil Physical Properties Research Articles

Improving the Spatiotemporal Transferability of Hyperspectral Remote Sensing for Estimating Soil Organic Matter by Minimizing the Coupling Effect of Soil Physical Properties on the Spectrum: A Case Study in Northeast China

Soil organic matter (SOM) is important for the global carbon cycle, and hyperspectral remote sensing has proven to be a promising method for fast SOM content estimation. However, because of the neglect of the spectral response of soil physical properties, the accuracy and spatiotemporal transferability of the SOM prediction model are poor. This study aims to improve the spatiotemporal transferability of the SOM prediction model by alleviating the coupling effect of soil physical properties on spectra. Based on satellite hyperspectral images and soil physical variables, including soil moisture (SM), soil surface roughness (root-mean-square height, RMSH), and soil bulk weight (SBW), a soil spectral correction model was established based on the information unmixing method. Two important grain-producing areas in Northeast China were selected as study areas to verify the performance and transferability of the spectral correction model and SOM content prediction model. The results showed that soil spectral corrections based on fourth-order polynomials and the XG-Boost algorithm had excellent accuracy and generalization ability, with residual predictive deviations (RPDs) exceeding 1.4 in almost all the bands. In addition, when the soil spectral correction strategy was adopted, the accuracy of the SOM prediction model and the generalization ability after the model migration were significantly improved. The SOM prediction accuracy based on the XG-Boost-corrected spectrum was the highest, with a coefficient of determination (R2) of 0.76, a root-mean-square error (RMSE) of 5.74 g/kg, and an RPD of 1.68. The prediction accuracy, R2 value, RMSE, and RPD of the model after the migration were 0.72, 6.71 g/kg, and 1.53, respectively. Compared with the direct migration prediction of the model, adopting the soil spectral correction model based on fourth-order polynomials and XG-Boost reduced the RMSE of the SOM prediction results by 57.90% and 60.27%, respectively. This performance comparison highlighted the advantages for considering soil physical properties in regional-scale SOM predictions.

Estimation of soil organic carbon by combining hyperspectral and radar remote sensing to reduce coupling effects of soil surface moisture and roughness

Soil organic carbon (SOC) is important in the global carbon cycle. Accurate estimation of SOC content in cultivated land is a prerequisite for evaluating the carbon sequestration potential and quality of soils. However, existing SOC prediction studies based on hyperspectral remote sensing neglect the spectral response of the physical properties of surface soil, leading to inadequate model generalization. With the exponential growth of remote sensing data, the development of pixel-level soil spectral correction methods based on multi-source remote sensing data has become an interesting and challenging topic. This method aims to minimize the effect of soil physical properties on spectra, thus addressing the poor spatiotemporal transferability of SOC prediction models due to uncertain variations in surface soil physical properties. In this study, a soil spectral correction strategy is constructed using satellite hyperspectral image (HSI) and synthetic aperture radar (SAR) images through multi-order polynomial regression and convolutional neural networks. This strategy considers soil physical variables such as soil moisture (SM) content and root mean square height (RMSH) of soil surface roughness. The soil spectral correction model and SOC content prediction model were established using 80 soil samples collected from Site 1. Afterward, the performance and transferability of both models were verified using the remaining 25 samples from Site 1 and 50 samples from Site 2. The results showed that: 1) The effect of SM and RMSH on the soil pixel spectrum can be significantly reduced after correcting HSI using soil spectral correction strategy. The correlation coefficients between the corrected pixel spectrum and the ground-based spectrum increase by over 60 % compared with those between the original spectrum and the ground-based spectrum. 2) Soil spectral correction improves the prediction accuracy and mapping capability of HSI for SOC content, with the highest RP2 of 0.743 and RMSEP of 3.455 g/kg at Site 1. 3) Compared with the original HSI-based SOC prediction model, the soil spectral correction strategy based on multi-order polynomial and convolutional neural network reduced the RMSEP of SOC prediction results at Site 2 by 5.082 g/kg and 5.454 g/kg, and the RP2 increased by 0.390 and 0.409, respectively. 4) When predicting SOC content from raw HIS, SM and RMSH contribute to more than 60 % of the bias, with SM having a larger bias than RMSH. The findings of this study emphasize the influence of soil physical properties on SOC prediction and contribute to the existing research on SOC mapping using HSI and SAR data.

Soil pore structure mediates the effects of soil oxygen on the dynamics of greenhouse gases during wetting–drying phases

The timing and magnitude of greenhouse gas (GHG) production depend strongly on soil oxygen (O2) availability, and the soil pore geometry characteristics largely regulate O2 and moisture conditions relating to GHG biochemical processes. However, the interactions between O2 dynamics and the concentration and flux of GHGs during the soil moisture transitions under various soil pore conditions have not yet been clarified. In this study, a soil-column experiment was conducted under wetting–drying phases using three pore-structure treatments, FINE, MEDIUM, and COARSE, with 0 %, 30 %, and 50 % coarse quartz sand applied to soil, respectively. The concentrations of soil gases (O2, nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4)) were monitored at a depth of 15 cm hourly, and their surface fluxes were measured daily. Soil porosity, pore size distribution, and pore connectivity were quantified using X-ray computed microtomography. The soil O2 concentrations were found to decline sharply as soil moisture increased to the water holding capacities of 0.46, 0.41, and 0.32 cm cm−3 in the FINE, MEDIUM, and COARSE, respectively. The dynamic patterns of the O2 concentrations varied across the soil pore structures, decreasing to anaerobic in FINE (<0.01 %) and MEDIUM (0.02 %), and to hypoxic (4.42 %) in COARSE. Correspondingly, the soil N2O concentration was the highest in FINE (101 μL L−1) and the lowest in COARSE (10 μL L−1), whereas the highest surface N2O flux was observed in MEDIUM (131 μg N m−2 h−1). As soil CO2 concentrations declined, CO2 fluxes increased from FINE to MEDIUM to COARSE. Most pores of FINE, MEDIUM, and COARSE were 15–80 μm, 85–100 μm, and 105–125 μm, respectively, in terms of diameter. The X-ray CT visible (>15 μm) porosity in FINE, MEDIUM and COARSE were 0.09, 0.17, and 0.28 mm3 mm−3, respectively. The corresponding Euler-Poincaré numbers were 180,280, 76,705, and −10,604, respectively, indicating higher connectivity in COARSE than in MEDIUM or FINE. In soil dominated by small air-filled porosity which limits gas diffusion and result in low soil O2 concentration, N2O concentration was increased and CO2 flux was inhibited as the moisture content increased. The turning point in the sharp decrease in O2 concentration was found to correspond with a moisture content, and a pore diameter of 95–110 μm was associated with the critical turning point between holding water and O2 depletion in soil. These findings suggest that O2-regulated biochemical processes are key to the production and flux of GHGs, which in turn are dependent on the soil pore structure and a coupling relationship between N2O and CO2. Improved understanding of the intense effect of soil physical properties provided an empirical foundation for the future development of mechanistic prediction models for how pore-space scale processes with high temporal (hourly) resolution up to GHGs fluxes at larger spatial and temporal scales.

Forest soil inoculation with Bacillus subtilus reduces soil detachment rate to mitigate rill erosion

Rill erosion is one of the most important types of soil erosion that has caused the destruction of many lands in recent decades, and its management has become an essential issue in world research. This study has evaluated the effects of soil physical properties induced by Bacillus subtilis OSU 142 (B. subtilis) on the soil detachment rate (Dc) and rill erodibility (Kr) in the inoculated soil, compared to the uninoculated soil in rill erosion-prone areas of Northern Iran. For measuring Dc, a hydraulic flume was used at 5 slopes (from 4.3% to 34.2%) and 5 water discharges (from 0.31 l m−1 s−1 to 0.67 l m−1 s−1) with 7 replications. Moreover, three physical properties of soils including the bulk density, mean weight diameter and total porosity of soils were measured before and after inoculation. Dc was found to be significantly lower (on average - 52% for the average slopes) in the inoculated soil with the B. subtilis (IB) compared to the uninoculated soil (UB). Rill erodibility (Kr), also was notably reduced in the IB soil (−70%) relative to the UB soil. The variability of Dc in the two studied soils showed a positive correlation to bulk density (R2 = 0.87), and a negative correlation to mean weight diameter (P < 0.01) (R2 = 0.89). The clustering of soils in two distinct classes (inoculated and uninoculated) by agglomerative hierarchical cluster analysis (AHCA) revealed a clear difference based on the physical properties of the treated and control soils. Based on the findings of present study, direct inoculation of B. subtilis can be proposed as a new and suitable technique for the improvement of soil physical properties and the reduction of soil detachment rate, especially in rill erosion-prone areas.

Effect of soil physical properties on soil infiltration rates

The physical properties of the soil are studied to understand the influence of soil properties on infiltration rate. The effect of soil physical properties on infiltration rates on logged-over forests was measured with a mini-disk infiltrometer across various levels of soil disturbances. Results of soil analysis suggest are mostly loamy texture and the bulk density has varied from 0.74 - 1.02 g cm−3, respectively. The basic infiltration rate has varied from a minimum of 0.61 mmhr−1 to a maximum of 45.22 mmhr−1 with an average of 3.81 mmhr−1. The results of simple regression analyses showed that there was little association between the physical properties of the soil and the infiltration rate. This study suggests that the high variation of infiltration rate in this study site is attributed to the high spatial variability of soil properties.

Effect of reduced tillage under various mulch types on soil fertility and yield of an organic pepper crop

The effects of mulching on soil characteristics and plant development for pepper crops conducted in organic farming were studied in the Sahel coast of Tunisia. The types of mulching used for tests are straw mulching, compost mulching, and plastic mulching which were compared with bare soil without mulching (control). The soil characteristics under these different mulching systems were evaluated by soil physical and biological parameters such as penetration resistance at 0-60 cm layer, microbial biomass, organic matter, and water content at 0-20 cm layer. Measurements were performed every week for 50 days. The obtained results showed that compost mulching led to a better growth rate and improved the structural and water state of cultivated soil by decreasing its resistance to penetration and increasing its organic matter content. It can be concluded that the "Beldi" organic pepper crop under conservation tillage and compost mulching has presented the best combination thus leading to motivating results such as the positive effects of soil physical properties and microbial biomass on the final crop yield.

Effect of Soil Physical Properties on Surface Runoff in Lukulo Upstream Watershed

Lukulo upstream watershed is one of the watersheds in Central Java Province, which passes through 3 districts; Kebumen, Wonosobo, and Banjarnegara. Lukulo upstream watershed has eight sub-watersheds located in areas with diverse topography and lithology. The diversity of topography and lithology affects the characteristics of the area, as does the physical condition of the soil. The physical condition of this soil affects the runoff. Soil’s physical properties control rainwater to run off and have important effects on runoff behavior in watersheds. This study aims to determine the physical properties of the soil against runoff in each sub-watershed and each part of the watershed. The method used uses a laboratory, studio, and field approach. The results obtained show that the physical properties of the soil in the Lukulo upstream watershed affect the amount of runoff resistance in the upstream area; in the downstream area the runoff is relatively good. The study also shows two different results. In the Loning watershed, the velocity of downstream runoff is higher than the upstream, while in the Lokidang and Medana watershed, level of surface water flow is lower in the downstream area.

Unsteady state contaminants transport in sandy mediums using CFD model

This study was conducted to provide a CFD simulation model to simulate the transfer of pollutants through sandy soils. A physical model and simulation model were designed and implemented with the help of CFD programs using COMSOL 5.4 software to study the process of transporting pollutants within the porous medium. To study the pollutant transmission in the porous media, a sand size of less than 0.36 mm diameters was used as porous media. For an analysis of the problem, several groups of factors were considered and assumed. The first group concerned with the physical properties of the media likes coefficient of adoption Kd. The second group represented the hydraulic factor of flow likes velocity. The results of the physical and CFD models showed there is a clear effect of soil physical properties due to the coefficient of adsorption Kd action. The velocity has a significant effect on the concentrations of pollutants and the time of transmission where the lower velocities produce lower concentrations and delayed transport of pollutants in the soil. The CFD simulated model showed that the change in the Kd-value has a significant impact on the results. The study also showed a good agreement between the results of the laboratory work provided by the physical model and that of the CFD model depending on several statistical indexes. This indicates that the CFD models could be considered as an efficient tool to simulate the complex problems of contaminates transport through a porous medium.

A soft-computing approach to estimate soil electrical conductivity

Soil apparent electrical conductivity (EC a ) is an indirect and rapid measurement for soil salinity, but because of its dependency on some physical and chemical properties of soil in addition to salinity, consideration of the soil extract EC is preferred for monitoring soil salinity, especially in semi-arid areas, though its measurement needs laboratory processes. This study, therefore, sought to develop a multivariable model to estimate the soil EC e from soil EC a , temperature, moisture content, bulk density, and clay percentage, using radial basis function (RBF) artificial neural network (ANN). In the first step, a set of tests was performed in laboratory in Box-Behnken design (BBD) to train the RBF-ANN. The developed RBF estimated the soil EC e with R 2 = 0.99 and RMSE = 0.005 dS.m −1 . Moreover, a quadratic response surface model (RSM) was also developed to compare with the RBF model. The sensitivity analysis revealed that EC a , moisture, bulk density, and temperature had the maximum to minimum effect on the estimation of soil EC e , respectively. In the second step, the RBF and RSM models were validated by another dataset obtained from three sites located in a semi-arid area. They were applied in-field with a multi-sensor portable device. The R 2 and RMSE of the estimation of EC e by the RBF were equal to 0.801 and 0.350 dS.m −1 , respectively. While, R 2 and RMSE of the RSM model were 0.735 and 0.439 dS.m −1 , respectively. The results of the study indicated excellent ability of the RBF-ANN in the rapid and precise estimation of soil EC e . • Modelling soil ECe based on some soil physical and electrical properties. • Developing a portable multi-sensor soil surveying device to estimate soil ECe. • Investigating the effects of soil physical properties on the models. • Validating the model and the device in-field and comparing with the lab results.

Non-uniform distribution of soil salinity along a transect of an irrigation field in an arid region.

We assessed soil salinity at field scale and suggested appropriate water and salt management practices for an arid region. Specifically, we focused on non-uniform salinity distribution along a transect in a research field. We also examined factors affecting the distribution of salt, including irrigation, drainage and salt movement. The non-uniform salinity distribution across the field was probably formed by irrigation management and distance from main drainage channel, while the effect of soil physical properties and groundwater was limited. The main drainage channel functioned well during the past irrigation period when abundant Karez water was available for leaching irrigation, and this contributed to the present non-uniform salinity distribution. Currently, farmers use less irrigation water, which does not promote desalinization. Vertical movement of soluble salts near the soil surface was dominated by irrigation management. Border irrigation promotes desalinization but drip irrigation enhances salt accumulation, with salinity increasing after irrigation because of high evaporation rates in the hyperarid climate. Based on these results, we explained the following points to local farmers in non-technical language: 1) a drainage channel is important for desalinization but the current channel is no longer sufficient to discharge salt from the field; 2) drip irrigation is effective for deficit irrigation but it enhances salt accumulation; 3) border irrigation has a positive effect on salt leaching from surface layers but the leached salt returns to the surface after irrigation ceases; and 4) there are high salinity layers below 60 cm soil depth, distributed widely across the fields.

Effect of soil physical properties in sugarcane growing tracts of prudential sugar factory zone in Chittoor District, Andhra Pradesh

The present study was formulated to study the effect of soil physical properties in sugarcane tracts of prudential sugar factory zone in Chittoor district of Andhra Pradesh. Two hundred and seventy (270) geo-referenced (GPS based) composite surface soil samples (0-15cm) were collected from 8 mandals of Prudential sugar factory zone results revealed that the texture of soils varied from sandy loam to sandy clay loam. The physical constants viz., bulk density ranged from 1.07 to 1.63 Mg m-3, particle density varied from 2.0 to 2.77 Mg m-3, porosity ranged between 36.33 and 58.25 per cent, water holding capacity ranged from 29.76 to 53.91 per cent and volume expansion varied from 1.15 to 21.01 per cent, respectively.

Pedogenesis of Mt. Sumbing Volcanic Ash above The Alteration Clay Layer in The Formation of Landslide Susceptible Soils in Bompon Sub-Watershed

Numerous researches on landslides have been carried out by many researches. However, studies on soil physical properties related to landslides potential in volcanic area are still rare. The objective of this study was to examine the effect of soil physical properties on landslides potential. To collect the soil sample, sampling area method was applied. The soil type used in this study was the residual soil. The values of clay liquid limit, plasticity limit, plasticity index, water content, COLE index were used to measure the physical properties of the soil. Organic material was used as the supporting data. The results showed that the soil in the command area showed high value of clay which exceeded 50%. Such high level conditions in each profile affect the liquid limit; plasticity limit, plasticity index, water content, COLE index and organic material. Based on the results, it can be concluded that residual soils with significantly high clay values illustrated the risk of landslide fields formation in Bompon sub-watershed. The clay soil layer was the controlled factor of soil movement.

Initial recovery of soil structure of a compacted forest soil can be enhanced by technical treatments and planting

Heavy harvesting leads to harmful soil compaction and negative effects of soil physical properties and rootability. We monitored the recovery of soil structure in a compacted forest soil, which had been treated with a combination of regeneration techniques (mulching, liming, planting of alder trees or a combination of those). Soil physical properties (relative apparent gas diffusion coefficient (Ds/D0), bulk density and the macropore volume) were measured in three successive campaigns, with two years between each, with fine root densities taken as a biological target variable.Distinct changes of soil physical properties were detected during the study period, mainly caused by the effects of the applied regeneration techniques. After four years, higher values of Ds/D0 and macropores indicated significant improvements of soil aeration in the topsoil. The deeper soil showed no distinct evidence of regeneration, regardless of the regeneration technique applied. However, rather a negative impact of mulching on soil physical properties was detected.The measured physical parameters, Ds/D0, bulk density and macropore volume correlate highly with observed fine root densities. In the topsoil, root density increases with increasing soil gas permeability, while in the deeper horizons only few macropores are occupied by fine roots for gas exchange.

Compressibility and elasticity of subtropical no-till soils varying in granulometry organic matter, bulk density and moisture

Soil compressibility and elasticity are fundamental physical properties related to soil strength and resistance to compaction. The objective of this study was to evaluate the effect of soil structural condition, granulometric composition, organic matter, and moisture on compressive and elastic properties of subtropical soils under no-tillage system. Undisturbed soil samples (a total of 536) from 0–0.075 and 0.075–0.15 m layers were capillary-saturated for 24 h and subjected to 6, 10, 30, and 100 kPa water tension, to determine the composition soil physical (bulk density BD and soil volumetric moisture θv) properties, and the functional soil properties: compressibility (precompression stress σp and compressibility coefficient Cc) and elasticity (decompressibility Dc and recovery Rc coefficients). Soil clay and organic matter (SOM) contents were evaluated using disturbed soil samples. Soil BD ranged from 1.15 Mg m−3 up to 1.67 Mg m−3, whereas soil σp ranged from 52.9 to 398.7 kPa, and increased with BD increase and decreased with an increase in SOM, clay and θv. Soil Cc ranged from 0.06 to 0.64, increased with rise in water tension, and had a significant inverse relationship with soil BD, and significant direct with SOM, clay and θv content for all studied water tension. These results suggest soils with high soil organic matter are less resistant to compaction, but may recover more from compaction. Soil Dc ranged from 0.0224 to 0.1416, and had an inverse relationship with BD and direct with SOM, clay content and θv. The mean Dc value of 0.0666 implies a rebound of about 0.17 in void ratio e, 14% in total porosity, and 0.12 Mg m−3 in soil bulk density, when assuming stress unloading from 300 (the load applied by a harvester, for instance) to 0 kPa. Soil elasticity is influenced by soil properties also controlled by soil moisture, such as soil bulk density and organic matter. Elastic behavior of the soil may be described primarily based on Dc, due its significant relationships with BD, θv, clay and SOM in different water tensions. These results show elasticity is influenced by soil structure, where soil management that improves structure is vital in the partial recovery after soil loading. Soil Rc (from 2.4 to 22.6%; with an overall mean of 12.1%) had most significant relationships between soil properties, but there was no discernible trend of relationships with soil properties; thus, extra care is needed when this parameter is used as indicator of soil elasticity. Soil elasticity and compressibility is increased by soil moisture and clay and organic matter contents, and decreased by soil compactness as suggested from the simple regression analysis. Further, when the integrated effect of soil physical properties is evaluated by multiple regressions, decompression and recovery coefficients are most influenced by soil bulk density and soil organic matter analysis, while compressibility coefficient is also influenced by volumetric moisture.

耕耘砕土に関する研究(第1報) : 土壌物理性の砕土におよぼす影響

耕耘砕土に関する研究(第1報) : 土壌物理性の砕土におよぼす影響

Effects of soil physical properties on erodibility and infiltration parameters of selected areas in Gidan Kwano

This study looked at the physical properties of soil of selected areas of Gidan Kwano campus of Federal University of Technology Minna, Nigeria and their effects on erodibility and infiltration parameters. Infiltration rate of the selected areas were conducted using a double ring infiltrometer and soil samples collected at different depths of 0 – 30 and 30 – 60 cm respectively. Collected samples were analyzed to determine physical properties such as moisture content, particles size, bulk density, porosity and organic matter. Textural classification was carried out to determine the percentage dominance of the various soil types present in the selected areas. Plot A has a steady infiltration rate after 11/2 hour at 0 cm/hr. While plot B had a steady infiltration rate after 30 minutes at 1cm/hr. The soil moisture count for plot A ranged between 9.54% to 14.56% while that of plot B range between 10.64% to 11.26%. The particle sizes analysis indicated that the soil type in plot A is mainly medium loam and predominantly sand clay loam in plot B. It is therefore concluded that, the study area is susceptible to erosion because of poor infiltration rate.Keywords: Erodibility, Erosion, Infiltration, Soil, Undisturbed, Water

Variability of physical properties of soil and rice grown under cover crops in crop-livestock integrated system

ABSTRACT The production systems of upland rice culture in Mato Grosso are not consolidated yet while the effects of soil physical properties and their correlation with rice yield in crop-livestock integrated systems are not defined as well. Therefore, this study determined the spatial variability of physical properties of soil and rice cultivated in no-tillage system under different cover crops, using principal components analysis and geostatistics. The experiment was conducted in Santa Carmen, northern Mato Grosso. A regular grid with 100 sample points distributed in an area of 26,400 m2 was installed. Soil and rice samples were collected to determine rice variables and soil physical properties. The average rice yield was 1.70 Mg∙ha−1, ranging from 0.70 to 3.12 Mg∙ha−1. The highest yields were observed in consortium with cowpea and brachiaria and were associated with lower incidence of grain spots, despite higher soil density and penetration resistance. The consortium with brachiaria, crotalaria, and sudangrass had lower yields, which was associated with higher incidence of grain spots, despite higher soil macroporosity and total porosity.

Effect of soil physical properties on infiltration rate

Excessive rainfall can cause runoff flows over the soil surface and as a consequence some amount of water will infiltrate into the soil. From a hydrologic modeling perspective it is necessary to estimate infiltration rate in order to calculate the actual runoff discharge. There are many parameters that can affect the infiltration rate such as soil texture, moisture and compaction. However, the most common equations used in hydrological calculations for estimating the infiltration rate do not consider the soil properties directly and estimate infiltration rate without any soil properties expressions. The purpose of this research was to investigate the relations between infiltration rate and soil texture, moisture and compaction. To achieve this purpose an experimental study was performed to show the effect of soil properties and their relations on infiltration rate by using non-linear regression.

Effects of soil physical properties on soil loss due to manual yam harvesting under a sandy loam environment

Soil degradation is a growing problem worldwide because it reduces the fertile top layer of the soil available for food production and one such degradative action is soil erosion due to the harvesting of crops. Soil loss due to crop harvesting with particular reference to yam tubers has not been quantified globally despite the fact that yam is a major staple food consumed worldwide and it is prevalent in many parts of Nigeria. Harvesting yams in our environment is usually done with the soil attached to the yams due to the fact that farmers do not want additional work of removing soil attached to the yams. This study investigates the soil physical properties that influence soil loss due to yam harvesting in Abeokuta, South-Western Nigeria and to assess the quantity of soil loss due to yam harvesting. Based on representative sampling area per location, yam tubers were harvested manually within the entire yam farmland from October to December 2012. Gross weight, net weight and the amount of soil adhering to the yams were measured. Effects of soil physical properties such as soil moisture content, heap bulk density, inter-heap bulk density and soil texture were investigated with respect to soil losses. The results showed that moisture content ranged from 4% to 15%, heap bulk density ranged from 0.93 to 1.29gcm−3 and inter-heap bulk density ranged from 1.03 to 1.50gcm−3. They all had a positive correlation with soil loss. Soil particle size analysis for Federal University of Agricultural, Abeokuta (FUNAAB) and Alabata revealed that sand content was (86.78% and 88.32%), clay content (10.69% and 7.6%) and silt content, (2.53% and 4.08%) respectively. Study also revealed that clay content of the soil positively influenced the total soil loss during the yam harvesting. The mean soil losses in Federal University of Agriculture, Abeokuta (FUNAAB) and Alabata village yam farms were 4303 and 2125kg/ha/harvest respectively. The study also revealed that soil moisture content at harvesting time and clay content are the key factors affecting soil loss due to yam harvesting. Consequently, soil loss due to crop harvesting should be considered in soil erosion control strategies, sediment budget and for better post harvest procedures.

Effects of Soil Physical Properties to the Corrosion of Underground Pipelines

Corrosion of metals in soil be able to change from comparatively fast material loss to insignificant effects, depending on soil environment. Corrosion is a process of deterioration of metal surfaces degraded into another compound. Soil is one of the medium known to have constituted to corrosion of metals. The soil creates an environment for the corrosion to react. The buried pipelines are exposed to the soil that may experience corrosion attack. The study of the soil as corrosion environment is important to mitigate the problem due to the environment and economy. There are factors that contribute to the corrosion process. This study concentrates on corrosion properties that expose to soil environment particularly underground pipelines. The mild steel coupons taken from actual pipelines, stimulating and analyzing the physic-chemical characteristics of the soil environment. The soil is sandy clay in natural. A total summed index of 2 numerical scale, thus, indicates that the soil tested was mildly to non-corrosive. The corrosion rate increase with increasing of moisture content and pH value. The observations on the coupon surface also did in order to study the morphology.