Silty Texture Research Articles

Can hydraulic-energy-indices be effectively used to describe the saturated hydraulic conductivity?

The saturated hydraulic conductivity (Ks) and water retention curve (SWRC) parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world. Therefore, Ks and SWRC are related with the soil physical quality (SPQ) and several SPQ indices can be derived from SWRC, such as the pore size distribution, relative field capacity, plant available water, drainable porosity, and soil hydraulic-energy indices (SHEI). It is well known that the soil structure can be assessed by using SHEI, but a possible physical relationship between Ks and SHEI was not examined yet. Therefore, the objective of this study was to investigate the behavior of Ks as function of SHEI for several soil textural classes. If this relationship be proved, then SHEI might be applied to improve the Ks prediction by PTF models. In this work, a data set of 395 measured SWRC's were fitted to the vG equation to obtain the SHEI to verify whether they are statistically correlated and physically dependent on Ks. The resulting parametric and non-parametric correlation results were split up according to six textural classes. The significant influence of Ks on at least one of the absolute SHEI (Aa or WRa) was verified on the numerical scale when all textures were grouped and on numerical and pF scales for clayey and silty textures. Ks showed significant impact on Aa and WRa indices in four textural classes. Furthermore, Ks had influence on the sum Aa + WRa denoted in pF scale for five of the six textural classes, with a significant linear correlation in the clayey texture when log (Aa + WRa) was applied. The significant and high correlation of Ks on the ratios WRa/AWC and Aa/φD was also observed in four of the six classes, and therefore the use of these indices is recommended for the development of PTFs for Ks prediction.

Loess chronology and composition as interpreted through the lens of fossiliferous lake sediments in central Illinois, USA

Silty lacustrine and paludal records spanning from the penultimate deglaciation (late Illinois Episode) to the present are preserved in kettles formed during marine isotope stage (MIS) 6 that lie adjacent to the MIS 2 Manito terrace along the valleys of the Sangamon and Illinois Rivers. Geochemical, mineralogical, particle-size, and chronological records from two basins, Smith Lake and Lake Ben, provide a unique opportunity to assess loess age and provenance of the south-central Laurentide ice sheet. Here, I focused on deposits of redeposited loess of the last glaciation (Wisconsin Episode). Other than subtle laminations and fossils of emergent and aquatic plants and animals, the silty texture, chemical composition, and mineralogy of the lake sediment closely resemble Peoria Silt (loess). Sediment-core records sampled from Smith Lake and Lake Ben in Mason County, Illinois, confirm rapid deposition of proximal loess derived from the nearby outwash plain of the Illinois River from ca. 30.9−18.0 calibrated (cal) k.y. B.P. From 18.0−14.7 cal k.y. B.P., deposition of proximal loess was gradually replaced by far-traveled (distal) loess chiefly derived from Superior lobe provenance and global dust. The succession is capped by a cumulic gleysol that was truncated by recent plowing. Proximal loess deposits in lakes Smith and Ben are composed primarily of very fine sand, coarse silt, and medium silt (125−16 µm) compared to the distal facies (fine silt and finer sediment: <16 µm). Proximal loess that originated from outwash of the Lake Michigan lobe contains abundant Ca, Zr, Sr, illite, and magnetic minerals. The distal facies contains relatively abundant Rb, Al, K, Si, Cu, and Pb, and it is enriched in smectite (relative to illite) and depleted in magnetic minerals. Radiocarbon ages on terrestrial gastropod aragonite in loess from the nearby New Cottonwood School and Thomas Quarry sites indicate that Peoria Silt deposition ended between 18 cal k.y. B.P. and 16 cal k.y. B.P. At these localities, the upper part of the record is complicated by the modern soil, which has altered soil organic matter and leached carbonate. At Lake Ben, the radiocarbon record of emergent aquatic vegetation indicates that sediment accumulation rates and the ratio of proximal to distal loess decreased at the correlative interval that yielded the youngest snail shell ages at Cottonwood School. The upward increase in element concentrations such as Al and decrease in coarse/fine silt ratios in the modern soil are prominent features in the Lake Ben record dating from 18−14 cal k.y. B.P. This correlation strongly suggests that many of the features of the modern soil were not developed into uniform parent material but, rather, were inherited from incremental addition of distal loess to proximal loess, collectively identified as Peoria Silt. The paucity of key elements (Cd, Hg, Se, Ag, Au) in this transition zone suggests limited contributions from western lobes (i.e., Des Moines and James lobes), but abundant Ti and Cu suggest a contribution from the Superior lobe. A new wrinkle in this interpretation is that the rise in elements such as Al, Rb, and Si suggests significant additions from generic dust from unknown sources.

Response of Three Barley Cultivars Hordeum vulgare L. to Water Stress Under Field Conditions

A field experiment was conducted in one of the agricultural fields located in the center of Hilla/Babylon, within latitude 32°31’ north and longitude 44°21’ east. During the season 2021-2022 in a soil with a loam silty texture. The aim of the study is to know the effect of water stress on the yield of green feed and grain and its components and the water use efficiency of the barley crop. A split-plot design with RCBD arrangement was used with three replicates. The irrigation treatments that include the comparison treatment (50% depletion of the available water) were occupied and three water depletion treatments (40, 60, 80%) of the amount of water for the control treatment, the main plot, while the cultivars occupied subplot No significant differences appeared between the control treatment and the irrigation treatment, 80% of the control treatment in the yield of green feed and grains, and thus it was possible to save water by 20% without a significant decrease from the control treatment. The irrigation treatments 80 and 60% showed higher efficiency in using water for grain production than the control treatment. The cultivars showed significant differences in yield, as Bohouth 244 gave the highest yield of feed and grain, and it did not differ significantly from cultivar IPA 99. Also, Bohouth 244 showed the best water use efficiency to produce a larger amount of grain, and it did not differ significantly from IPA 99.

Physicochemical Properties and Fertility Level of the Vertisols Surface Horizons for muskuwaari [Sorghum bicolor (L.) Moench] Cultivation in the Sudano-Sahelian zone of Cameroon

Poor agricultural practices coupled with climatic aberrations have led to the degradation of vertisols intended for muskuwaari cultivation and consequently result in a drastic drop in crop yield. Faced with this situation, the knowledge of the state of their physicochemical properties and fertility level becomes a priority to develop strategies to restore their fertility. In this perpective, this work is inscribed to contribute to the knowledge of the state of the physicochemical properties of vertisols and the evaluation of the associated fertility level. To do this, 6 samples of cultivated vertisols associated with the rhizosphere were surveyed and collected in the surface horizon (0-30 cm) including, three samples in each administrative region of the North (Houla, Bangli, Pitoa) and the Far North (Dargala, Ibba, Moutourwa) respectively. Physical characterisation revealed that almost all of these vertisols have rather a silty texture with a very small proportion of the clay fraction (25.66-28.66%) compared to normal (40-80%). Chemically, acidity is spatially variable with generally low proportions (pH= 5.50-7.16) compared to normal (7-7.5). These vertisols also have very low proportions of nitrogen (0.03-0.08 %), organic carbon (0.95-1.9%), organic matter (1.63-3.39%), C/N ratio (19.45-49.14%), assimilable phosphorus (5.92-45.31 mg/kg), the sum of exchangeable cations (4.10-7.56 meq/100 g), cation exchange capacity (16.51-18.49 meq/100 g) and saturation of the exchangeable complex (23.33-43.14%) compared to normal especially for organic matter (2-4%), the sum of exchangeable cations (25-40 meq/100 g), the cation exchange capacity (20-45 meq/100 g) and the saturation of the exchangeable complex (80-100%). Therefore, the fertility level associated with these vertisols was very low with at least one limiting parameter. One fertility rehabilitation strategy for these vertisols is based on the use of inputs such as mycorrhizae and/or compost.

Short-term land degradation driven by livestock grazing does not affect soil properties in semiarid steppe rangelands

The soil–vegetation relationships are reciprocal and fundamental for terrestrial ecosystem integrity. However, the long-term degradation of vegetation cover alters edaphic conditions, which can lead to degradation of habitats, and obstructs proper ecosystem functioning. This study aimed to assess the effects of the degradation of perennial steppe vegetation due to overgrazing (i.e., continuous and free grazing) on the physicochemical characteristics and soil fertility in the steppe rangelands of Halfa (Macrochloa tenacissima syn. Stipa tenacissima) of semi-arid areas in Algeria. The edaphic parameters of the superficial horizons of degraded steppes and other undegraded steppes were compared in order to suggest adequate strategies for rangeland management and remedy the degradation of vegetation and thereby ensure the sustainability of these agro-pastoral systems. The soil, collected from the surface horizons (A1 and A2) of pedological profiles, was analyzed according to standard methods of soil physicochemical analyses to determine the particle size fractions (clay, silt, and sands), pH, electrical conductivity (EC), total and active CaCO3, organic matter (SOM), organic carbon, total nitrogen, and the C:N ratio. The distribution and variation of soil parameters between horizons and the two types of steppes were examined using generalized linear mixed models and redundancy analysis. Findings of this study revealed that the degradation of steppe vegetation cover by short-term overgrazing did not cause a significant variability in soil physicochemical parameters between degraded and undegraded steppes and the horizons A1 and A2. The sites studied have clayey–silty textures in non-degraded steppes and coarse textures dominated by sands in degraded steppes. The edaphic environment of the Halfa grass steppes was characterized by a calcareous substratum with high carbonate content (total CaCO3 = 36.8–41%, active CaCO3 = 17.5–18.5%), with an alkaline pH (8.09–8.19) and EC averaging 0.99 ± 1.24 dS/m. Soils had low SOM contents (1.42–2.93%), organic carbon (0.82–1.64%), and nitrogen (0.1–0.15%). The strong positive correlations recorded between the fine-size fractions, SOM, total CaCO3, nitrogen, and EC indicated good soil structural stability in undegraded steppes, while the negative correlations between these same variables with sand and pH substantiate the structural degradation of the soil. The negative correlation between C:N ratio and SOM indicated that the rate of SOM mineralization was rapid in semiarid steppes, with a higher fertility state in the undegraded steppe. Our findings suggest and urge to implement a restoration plan against the degradation of semi-arid Halfa steppes in order to avoid the irreversible state of soil and habitat destruction in the future because even the degradation of rangeland plant cover due to livestock overgrazing—in the short term—has not affected the edaphic characteristics of steppe rangelands.

A paleopedological approach to understanding Eocene environmental conditions in southern Patagonia, Argentina

The Eocene Las Flores and Koluel-Kaike formations in southern Patagonia (~48° S, Golfo San Jorge Basin, Argentina) are pedogenically modified fluvial and fluvio-eolian successions, respectively, which document early-middle Eocene environments at mid-paleolatitudes in the Southern Hemisphere. In order to reconstruct the paleoenvironment for the Las Flores and Koluel-Kaike formations, we performed a multiproxy and coordinated study of sediments and paleosols of both units, considering abiotic components. Using detailed sedimentology and paleopedology (macro- and micromorphology), bulk paleosol geochemistry and clay mineralogy, and organic carbon concentrations and stable isotope (δ13Corg) compositions, we show that the Las Flores and Koluel-Kaike paleosols are overall Ultisol-like paleosols, mineralogically and chemically consistent with a high to high-moderate degree of weathering, and developed on different parent materials (sedimentary with sandy and silty texture vs. silty volcaniclastic). Climate proxies and a comparison with modern Ultisols with similar features suggest that these paleosols formed under a broadly tropical-temperate and humid-subhumid climate with distinct seasonality. Overall, these combined data record long-term environmental conditions during the Paleogene (early-middle Eocene), and preserve a record of Eocene terrestrial climate in the Southern Hemisphere. This research is relevant for understanding latitudinal climatic gradients during warm periods like the Eocene, a key knowledge gap for future predictions, and these sites are particularly important because mid-latitude reconstructions in the Southern Hemisphere are the poorest resolved.

Soil Physical Characteristics and Saturated Hydraulic Conductivity in the Landform of Barito Delta, Kalimantan, Indonesia

We explore the soil physical characteristics in wetland of Barito Delta from primary data of soil sample and electrical resistivity measurement with the support from some secondary data. We also estimate saturated hydraulic conductivity (Ks) in Barito Delta from soil physical characteristics applying Saxton and Rawls (1986) and Weynants et al. (2009). Soil texture profile is determined from interpolation of soil fraction in each layer applying Bayesian statistics to analyze soil physical characteristics in the landforms of Delta. Clay is the dominant soil fraction in the soil of Barito Delta. Clay fraction percentage decrease along the depth of soil profile as it reaches fine sand particles deriving from ancient sedimentation from the past. It is an opposite with soil organic matter content that has contrast value from 1st to 2nd soil depth, but a few discrepancy from 3rd depth to downward direction. The content of clay in the soil depends on the sedimentation activity in the landform. Clay is dominant soil particle in the Delta; in case, it is in flat area and there is no intensive of sea water sedimentation such as in Basin of Peat Anticline and Natural Levee. In more than 2 m depth of soil, loamy sand and silty clay textures are mostly in the landform that is influenced by sea water activity, while by river water is clay loam. Ks values from Saxton and Rawls (1986) are close to Ks values from the measurement of previous studies. Ks values are generally small in Barito Delta that is mostly ranging from 1.10−7 to 2 m s−1. Ks values are larger following the depth of soil profile. The values of Ks are smaller in Basin of Peat Anticline and Natural Levee than in Tidal Flat and Beach Ridge. It is because both landforms have clay as dominant soil particles.

Soil structure effects on deformation, pore water pressure, and consequences for air permeability during compaction and subsequent shearing

Soils may react to the impact of wheeling with volume-changed deformation by compaction and volume-constant deformation by shearing. The different deformation mechanisms with their deteriorated effects on soil pore functions have been studied frequently, but less is known about the compaction/shearing-induced deformation on structured soils as compared with homogenized substrates. In order to document both the effect of aggregation on soil deformation behaviors as well as the sensitivity due to texture, compaction and shearing measurements were performed on soil samples from the A- horizon of a homogenized Luvisol (a silt loam with a bulk density of 1.37 g cm-3) and two structured Gleysols (clay loam soils with bulk densities of 1.34 g cm-3 and 1.11 g cm-3). The changes of vertical settlement (ΔH), air/water-filled pores (ε/θ), air permeability (ka), and pore water pressure (uw) during compaction and subsequent shearing were studied. Results showed that the soil deformation behaviors due to compaction and shearing depended highly on the level of applied normal stress, especially on structured soils. At a normal stress of 50 kPa, which was smaller than the precompression strength, the structured Gleysols had only minor compaction-induced deformation (ΔH: 0∼1 mm) and a contractive shear behavior. At a high normal stress of 200 kPa, which exceeded the precompression strength, both homogenized and structured soils displayed greater compaction-induced deformation (ΔH: 3.5∼6.0 mm) and a dilative shear behavior. Compared with static loading, cyclic loading resulted in further deformation and dilative shear behaviors in both structured and homogenized soils. In addition, the structured soils showed a smaller decrease in ε/θ and maintained 10 times higher ka value than homogenized soils. However, shearing reduced the inter-aggregate pore continuity and enhanced the relative functionality of the sheared intra-aggregate pores, as was proofed by the more pronounced changes of uw (Δuw) in the structured soils (from -93.0 hPa to +335.6 hPa) compared with that in the homogenized silt loam (from +2.1 hPa to +140.2 hPa). In conclusion, the well-structured clayey soils exhibited less deformation during compaction compared with the homogenized (tilled) soil with coherent structure and more silty texture. The dynamic stress application and shearing resulted in more intense weakening of soil structure because the accessibility of particle surfaces for mobilized water coincides with an enhanced stress dependent swelling and sliding due to the rapidly increased uw.

Mapping and Environmental Diagnosis in Native Acai Areas in the Amazon

For several decades, the Acai orchards (acaizais) have directly influenced the survival of the families in the Amazonian floodplains. In this period, the production of the Acai fruit for local consumption was ceased and became an export item produced in intensive management, resulting in an increase in orchards in the floodplains and the emergence of dryland plantations, no longer representing a typical extractive activity in the Amazon. The objective of this study was to map the classes of use and coverage, and the occurrences of the Acai orchards massifs, as well as to analyze the physical and chemical parameters of five islands in the municipality of Igarapé-Miri, State of Pará, Brazil, where there is a great occurrence of productive Acai orchards. This work evaluated the following islands: Jarimbu, Mamangal, Itaboca, Mutirão, and Buçu, where geolocalized collections were carried out in the areas with the highest occurrence of Acai orchards, both to assist in the classification of images and for soil sampling. August 2019 Planet images were processed using the unsupervised method, where seven classes of cover use were obtained: hydrography, exposed soil, urban, alluvial, lowland, arboreal, and agriculture areas. Therefore, occurrences of productive orchards were identified and correlated to the good attributes of soil fertility in the floodplains under continuous flooding and sedimentation. The correlation confirmed the higher productivity of Acai in the Alluvial and Lowland classes, which predominate in the evaluated area, presenting soils considered fertile with a loam-clay-silty and loam -silty texture, high base saturation (greater than 50%), high organic matter content, and significant presence of potassium and phosphorus.

Evaluating the Trend of Changes in Bed Sediments Gradation over the Sistan River

Sediment movement in rivers is one of the most important indicators to evaluate the health of an ecosystem. Bed load different specification such as shape, dimensions and other statistical parameters of this sediment reflect the hydraulic and hydrological conditions governing them, directly. To investigate the changes of particle aggregation of Sistan river bed, four sediment samples were collected from the Sistan river. After aggregation of sediments in the laboratory, sediment diameter (D50) and uniformity coefficient (Cu) was calculated, and using inverse distance weighting (IDW) method, the mentioned parameters for the Sistan river from Jarikeh up to the AfzalAbad plugs place were interpolated and parameters using ARC-GIS software was zoning along the river. Results showed that Sistan river bed material is sand and silt, 3 km to the beginning and at end of the study interval based on the English standard classification it is silty texture and the rest of bed is sandy texture. 11 kilometers beginning and the end of the river also from 20 +721 kilometer up to about 12 kilometers has also a good aggregation. The entire river except for the middle section of river from the 13 +244 km to extent of 4 km river bed has non-uniform soil.

The Effect of Bio, Organic and Mineral Fertilizations on the Activity of the Urease, L-Glutaminase and L-Aspartase Enzymes in the Soil

The study aimed to investigate the effect of the application of various sources of fertilizers on the activity of urease, L-glutaminase, and L-aspartase enzymes in the rhizosphere and bulk soils. Pots experiment was carried out in the wire canopy in one of the fields affiliated to the Faculty of Agriculture - the University of Qadisiyah for the summer season 2018 in soil with a silty loam texture. Seeds of mung bean crops were cultivated of a local variety (Khedrawi). The treatments of the study were two levels of nitrogenous mineral fertilizer (urea) (M1 and M2) (20 and 40) kg.N.h-1, respectively, a single level of organic fertilizer (poultry waste) (10 tons h-1), a single level of bio-fertilizer with Pseudomonas fluorescens bacteria, the control, and their interactions. The experiment was carried out according to Completely Randomized Design (C.R.D) with six replications. Means were compared according to the (L.S.D) test at the probability level (α=0.05(. The efficiency of urase, L-clotamene, and L-aspartase in the soil of the root zoon and bulk soil were estimated for all study parameters 30 days after planting. These measurements were done once again for some characteristics of vegetative and root growth after 60 days of planting.
 The bio-fertilizer treatment (B) resulted in the highest increase in the efficiency of the urease enzyme and L-aspartase for 30 days of cultivation compared to the control treatment that recorded the least value of the enzyme activity average (45.22 and 42.54) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and bulk soils. These values were increased after 60 days of cultivation (45.34 and 43.16) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and bulk soils. This treatment achieves the highest increase in the activity of L-enzymes (25.89 and 24.72) µg N-NH4+.g-1 soil.2h-1, respectively, for the region of the rhizosphere and beyond. It increased after 60 days of cultivation (26.23 and 25.06) µg N-NH4+.g-1 soil.2h-1, respectively, for the region of the rhizosphere and bulk soils. The treatment of poultry wastes (O) resulted in the highest increase in the value of the activity of the L-clotamines enzyme in the rhizosphere and bulk soils for a period of 30 days from planting (43.47 and 57.39) µg N-NH4+.g-1 soil.2h-1, respectively. Its activity values then increased after 60 days of cultivation, reaching (44.33 and 40.43) µg N-NH4+.g-1 soil.2h-1, respectively.
 The overlap treatment between poultry residues and biofertilizers (OB) achieved the highest increase in the activity value for the urase enzyme, L-clotamines and L-aspartase in root zoon soil and distant soil for 30 days of cultivation (54.47, 46.84 and 28.28 µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and (49.14, 37.81 and 23.94) µg N-NH4+.g-1 soil.2h-1, respectively. The activity of enzymes then increased after 60 days of cultivation (54.56, 47.69 and 28.62) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere (49.23, 38.67 and 24.18) µg N-NH4+.g-1 soil.2h-1, respectively, for the bulk soil. The combination treatments between poultry residues, bio-fertilizer, and urea at level II (OBM2) achieved the highest increase in the activity values for urease enzyme, L-clotamines and L-aspartase in root zoon soil and bulk soil for 30 days of cultivation (58.46, 48.58 and 30.40) µg N-NH4+.g-1 soil.2h-1, respectively for the rhizosphere, and (54.13, 46.30 and 27.62) µg N-NH4+.g-1 soil.2h-1, respectively, for the bulk soil. The activity of enzymes then increased 60 days after planting (58.55, 49.44 and 30.74) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere (54.22, 47.15 and 27.96) µg N-NH4+.g-1 soil.2h-1, respectively, outside the rhizosphere.

Phytoremediation of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediments using Rhizophora mangle

A phytoremediation experiment was carried out in mesocosms to investigate the performance of Rhizophora mangle in the remediation of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediment contaminated with crude oil. The water pH of the experiments (phytoremediation and natural attenuation) ranged from 4.9 to 8.4 at 0 and 90 days, respectively. The oxy-reduction potential (Eh) ranged from oxidising (108.0 mV, time 0) to reducing (approximately −110.0 mV, time 90) environments. Dissolved oxygen (DO) ranged from 5.7 mg L−1 (time 0) to 4.5 mg L−1 and 3.6 mg L−1 (time 90) in phytoremediation and natural attenuation, respectively. The sediments had silty texture and an average concentration of 5% organic matter (OM). Phytoremediation (60.76%) showed better efficiency in the remediation of the 16 PAHs compared to natural attenuation (49.57%). Principal component analyses showed a correlation between the concentrations of PAHs with pH, Eh, OM and DO in both experiments.

Physical and Chemical Properties of Soil in the Sahelian Region: Case Study in Nioro du Rip, Senegal

The locality of Nioro du Rip is facing intense erosion, loss of agricultural land, soil pollution and soil degradation. Today, there is limited information about the soil physical and chemical properties in the locality. In this work, we describe the main essential factors or mechanism that control the evolution of the soil in the study area.
 The physical and chemical properties of soils encountered along a NE-SW transect in are analyzed in this paper. The statistical analysis results revealed low structural stability of soils in general, due to their low organic matter content and exchangeable bases and their predominantly silty texture. A net trend towards acidification, which is more pronounced in the lower-bottom and terrace soils, provides information on the conditions that are increasingly unfavorable to agricultural development.
 The multivariate principal component analysis (PCA) identified the preponderance of two factors among the four primarily involved in soil geochemical composition. These include a mineralization process (expressed through the first principal component (PC1), which causes soils to be rich in elements (Ca2+, K+,C, N, MO) controlling their structure and fertility level; The PC2 axis expresses the spatial differentiation phenomenon of the soil granulometric composition: soils forming cluster poles according to their textural affinity in the projection of the plane formed by these two components , with on one side the sandy-dominated soils of the shallows and terraces and on the other the clay-dominated soils of the plateau and the slope. A clear reversal of textural polarity in the studied topo sequence that must be blamed on the strong water erosion in this area.

Core surprise: What's inside a plate boundary?

Despite the fact that 90% of global seismicity occurs at plate boundary faults, our understanding of their internal structure is lacking. It’s not easy to see inside a plate boundary fault – typically composed of a high-strain fault core surrounded by a fractured damage zone – and when we can, it often requires expensive drilling projects that yield limited information on the internal structure of the whole fault. Understanding the internal structure of large faults is crucial, because their chemical and mechanical properties control how and where earthquakes rupture, nucleate and propagate. This in turn limits the size of the earthquake or the amount of radiated seismic energy, and consequently the severity of surface damage. The 1999 magnitude 7.7 earthquake along the Chelungpu plate boundary fault, for example – the second deadliest earthquake in Taiwan’s recorded history – saw significant variations in slip and ground motion at different locations along the fault which resulted in large local variations in casualties and damage. Subsequent field investigations related these variations to changes in the fault’s structure (i.e., clay width, geometry), which in turn controlled how the fault moved.

Influence of Anthropic and Topographic Factors on the Physicochemical Properties of the Soil around Temporary Pools in Ferlo, North Senegal

The temporary ponds at Ferlo constitute wetlands whose pastoral activity is of paramount importance in the economy of Senegal. These zones are characterized by a fairly specific microclimate (soft and humid), a shallow depth of the water table, alternating phases of submersion and exudation whose functioning is linked to the soil. Thus the restoration and conservation of these wetlands requires a good knowledge of the soil factors.
 The objective of this study is to compare the physico-chemical parameters of the soil around temporary pools in grazed and ungrazed areas and different topographical units in order to determine their relative similarities.
 The samples taken at different horizons from seven soil pits (P1, P2, P3, P4, P5, P6 and P7) opened in the different morpho-pedological facies of two grazed ponds and one ungrazed pond were analyzed in the laboratory.
 The results obtained show that the soils of Ferlo have a sandy texture and low fertility in the slopes and plateaus. However, they have a balanced texture and average fertility in ponds and ungrazed areas. The factorial analysis made it possible to highlight three distinct soil classes. A class of sandy texture soil with very low chemical fertility comes from the plateau. A class of soil with a balanced texture which is rich in cation and calcium exchange capacity found in the low zones of strong mineralization. A last class rich in chemical element with a silty texture which is found in wooded areas.
 These results thus reveal the predominant influence of anthropic and topographic factors on the evolution and physico-chemical composition of the soil.

Soil Fertility Evaluation for Strategic Direction Jati Plus Perhutani (JPP)

Soil fertility evaluation conducted to assess the characteristics of the soil and determine the significant constraint factor and alternative supervision. This research aims to determine the limiting factors of soil fertility in Jati Plus Perhutani (JPP) clonal forestry and routine plantation at the research sites in a few years of planting and determining the strategic directives of supervision. Total land of 12 soil map units evaluated based on a representative profile in the semi-detail level on the research sites of FMU Ngawi and Pemalang. Data collection of soil fertility was based on Soil Research Institute and the National Soil Survey Center guidelines. Classification of soil fertility shows that the soil was dominated by silty texture and has a flat to a moderately steep slope. Soils at the research sites have low infiltration rates, high ability to restrain water, difficult cultivation, and a high potential for a run-off on sloping land. Assessment of soil fertility status at the research sites shown of CEC and base saturation high to very high. C organic, P2O5, and K2O are rated very low to low, strategic directives for land supervision and cultivation in the research sites are the application of organic substances, intensive soil management and implementation of soil conservation.

Effect of Crop Residue Removal and Straw Addition on Nitrous Oxide Emissions from a Horticulturally Used Soil in South Germany

Core Ideas The main aim was to reduce N2O emission through crop residue removal or N immobilization through straw addition in fall. Annual N2O emission was reduced by 74% through removal of vegetable crop residues in fall. N2O emission in the removal treatment was as low as in the unfertilized control. Straw addition in autumn failed to reduce N2O emission (p = 0.057). Vegetable production, such as cauliflower (Brassica oleracea var. botrytis L.) or broccoli (Brassica oleracea var. italica P.), is often associated with high N surpluses, posing the risk for substantial N losses. Straw addition in autumn to immobilize surplus N over winter or removal of vegetable crop residues were shown to reduce nitrate leaching efficiently. However, the effect of these management measures on the release of nitrous oxide (N2O) is still unclear. We determined N2O fluxes from a vegetable field with a silty texture in southern Germany over 2 yr in the following treatments: no N fertilization (−N), conventional N fertilization without (CON), and N fertilization with crop residue removal (−CR) or straw addition (+S). Marketable fresh matter yields and N uptake showed only minor differences among all N‐fertilized treatments. Enhanced N2O fluxes occurred over a period of nearly 6 mo in the first year in autumn and winter after crop residue incorporation. Positive correlations between N2O fluxes and driving soil variables suggested denitrification as the major N2O source. Cumulative N2O emission ranged between 5.2 (−CR) and 37.2 kg N2O–N ha−1 yr−1 (CON). Crop residue removal reduced N2O emission in CON very efficiently by 74%. Straw addition reduced N2O emission in only 1 yr. The N2O emission factors were 4.3, 1.9, and 3.1 for CON, −CR, and +S, respectively. The high N2O reduction by crop residue removal seems to be promising in terms of mitigation, but long‐term effects, such as missing humus reproduction, should be considered in future studies.

ARTIFICIAL NEURAL NETWORK AND STEPWISE APPROACH FOR PREDICTING TRACTIVE EFFICIENCY OF THE TRACTOR (CASE JX75T)

The aim of this study is to develop and predict models of tractive efficiency using the artificial neural network and stepwise approach. The tractive efficiency of tractor (CASE JX75T) was measured experimentally. Experiments were conducted in the site of Basrah University. Which had silty clay soil texture. The field conditions included effect of two level of cone index (550 and 980 kPa), two level of moisture content (8 and 21%), three forward speeds (0.54, 0.83 and 1.53 m/s) and four level of tillage depths (10, 15, 20 and 25 cm). The results illustrated that both developed models (stepwise approach and ANN technique) had acceptable performance for predicting tractive efficiency of tractor under various field conditions. However, ANN model outperformed stepwise model, where 4-7-1 topology showed the best power for predicting tractive efficiency with R-squared of 0.97 and MSE of 0.0074 with Levenberg-Marquardt training algorithm. The analysis of variance demonstrated that the studied parameters had single significant effect on tractive efficiency. The most parameter influential on tractive efficiency was tillage depth followed forward speed, cone index and moisture content.

KARAKTERISTIK DAN PRODUKTIVITAS LAHAN SAWAH IRIGASI DI KECAMATAN DUAMPANUA KABUPATEN PINRANG

Land potential can be assessed from biophysical land suitability including soil characteristics, climate, and land management. This study aims to determine the potential of paddy fields in Duampanua Sub-District, Pinrang District for irrigated paddy field based on the land biophysical characteristics. The method was qualitative and quantitative approaches. Field surveys use purposive sampling method with 3 object observation. The land suitability class evaluation uses a simple limiting factor approach according to FAO (1976). To support the analysis of rice production data, 30 farmers were interviewed in 3 (three) observation units. The results showed the average rainfall of 2,780.2 mm/year with 9 wet months and 3 dry months categorized as type B2 (Oldeman). The results of soil samples analysis showed the characteristics of the soil with a silty clay texture, silty clay loam and clay; bulk density ranges from 1.36-1.66 g/cm3; cation exchange capacity ranges from 49.64 - 79.75 cmol/kg clay; soil pH ranges from 5.26-5.97; base saturation ranges from 36% - 46.4%; and C-organic ranges from 1.34% - 1.38%. The most dominant types of minerals are orthoclase, biotite, pyroxene, augite, opaque and clay with the symptoms of micropedological concretions and nodules. The land suitability class in the three land units for irrigated paddy rice is classified as S2nr (quite suitability in accordance with the limiting factors for nutrient retention including: base saturation, pH, and C-organic). The average productivity in land units I is 5.1 ton/ha, land unit II is 4.5 ton/ha, and in land units III 5.26 ton/ha.

An environmentally friendly soil improvement technology for sand and dust storms control

Background: Dust storms occur when unchecked, strong, or turbulent winds combine with exposed loose and dried soil surfaces. Sand and dust storms have a significant impact on society, economy, and environment at local, regional, and global levels. The environmental and health hazards of such storms cannot be permanently reduced, however, by taking appropriate measures, its impact can be reduced. The present study aimed to investigate the effects of microbial precipitation of calcium carbonate (CaCO3) as a biocompatible agent on soil stabilization and control of dust storms using ureaseproducing bacteria (UPB) as a biological improvement technique, which were isolated, identified, sprayed on the soil surface. Methods: For this purpose, the erosion of bio-cemented soil samples was investigated experimentally in a wind tunnel under the condition of wind velocity of 0 to 98 km.h-1 in two soil types with sandy and silty texture in a completely randomized design with three replicates. Results: The investigation of the threshold wind velocity of soil particles showed that soil particles began to move at velocity of 8 and 10 km.h-1 in silty and sandy soils, respectively, but in all biological samples (MICP), particles did not move until the wind speed reached 97 km.h-1. It was also revealed that the weight loss of all MICP-treated samples at different wind velocities was significantly reduced compared to the control group. Differences in the amount of soil loss among bio-cemented samples and control treatments were even superior at higher velocities, so that at velocities more than 57 km.h-1, soil losses increased significantly in the control group, while in soils treated with bacteria, soil loss was very low (about 2.5 kg.m-2.h-1). Comparison of the bacteria used in this study also showed that Bacillus infantis and Paenibacillus sp3 had high efficiency in controlling dust storms. Conclusion: The formation of abrasion-resistant surface layers on soil samples treated by biocementation showed that cementation by biological methods could be an effective way to stabilize surface particles and control sand and dust storms.