Delta Soils Research Articles

Soils of natural, arable and fallow Lands of the Selenga River delta

Soil-geographical investigations were made in the Selenga river delta (the southeastern coast of Lake Baikal) in the summer of 2017 and 2018. The Selenga delta developed Fluvisols aridic, Fluvisols umbric (gleyic), Fluvisols humus, Fluvisols mollicgleyic, Fluvisols Histic-gleyic, Folic-podburs, Gray (metamorphic) and Folic-gray soils. Fertile soils of the second bottom with Chernozems and Phaeozems are used as arable lands. Agricultural lands of terraces with Gray and Folic-gray soils are used as pastures. The soils of the low floodplain are put to agricultural use. It was established that the soils in most of agricultural lands are in satisfactory agricultural condition. The upper horizons of Gray soils under forest and Chernozems under steppe in natural condition have high humus concentrations. In soils permanently used in agriculture, humus content decreases. In fallow lands, its concentrations are recovering. The reaction of the medium (pH of water) in the soils is largely neutral. Gray soil under forest is distinguished by slightly acidic reaction. It was found that the soils of the Selenga delta have mostly a light granulometric composition.

Soil moisture adsorption capacity and specific surface area in relation to water vapor pressure in arid and tropical soils

This study is devoted to predict water vapour adsorption and hydro-physical properties of arid soils in middle Nile Delta (Farm of the Faculty of Agriculture, Shebin El-Kom, Egypt) and of tropical soils ( Felix and INIAP Farms) in Quevedo zone, Los Rios, Ecuador. The vapour pressure and isothermal adsorption of water vapour is used to predict soil moisture adsorption capacity ( Wa ) and the specific surface area. To achieve these objectives, four soil profiles at different depths were investigated to indicate the status of hydro-physical properties of the studied area. The 1 st & 2 nd profiles are sandy loam ( Felix Farm ) and clay loam soils ( Shebin El-Kom Farm ), and 3 rd & 4 th are clay soils ( INIAP Farm) . Data of soil-water adsorption (W%) at different relative vapor pressures P/Po are obtained for the studied soil profiles, where the W% values increased with increasing P/Po from 1.87% to 10.01% in the 1 st and 2 nd sandy loam and clay loam soil profiles, and reached 27.44% in the 4 th clay soil profile. The highest values of water adsorption capacity ( Wa ) were observed in the clay depths of 60 – 90 cm and 90 – 120 cm (INIAP-soil profiles) while the lowest values were in the subsurface depth (30 – 60 cm) of soil profiles 1 st and 2 nd . T he other hygro-physical properties such as adsorbed layers and maximum hygroscopic water were obtained. The specific surface area ( S ) in sandy loam 1 st &2 nd soil profiles is ranged from 113m 2 /g to 187m 2 /g and raised to 385m 2 /g and 553m 2 /g in the 3 rd & 4 th clay soil profiles. The corresponded values of the external specific surface area ( Se ) ranged from 42m 2 /g to 98m 2 /g and 74 m 2 /g to 252 m 2 /g respectively. Two equations were assumed (1) to predict P/Po at water adsorption capacity ( Wa ), and (2) to apply Wa in prediction of soil moisture retention i.e., ѱ(W) function at pF < 4.5.

Tracking Changes in Soil Fertility at North Nile Delta, Egypt Using GIS Techniques

Tracking changes in soil fertility is important to make essential decisions and strategies to achieve more sustainable agricultural systems. The main objective of this research was to evaluate and tracking changes of soil fertility status after 9 years ago from its first time of evaluation in the same area. The study area is situated at the latitude 31◦ 14΄ to 31◦ 29 E and 31◦ 14΄ to 31◦ 30 N (total area about 705 km2) in North Nile Delta soils using GIS techniques to prepare the soil fertility status map. Accordingly, 16 soil samples were collected based on the variability of land at a depth of 0-20 cm according to the previous study. The soil samples were analyzed for their some physiochemical properties and fertility properties. Evaluation of soil fertility and calculation of Fertility Index was performed using the Agriculture Land Evaluation System for arid and semi-arid regions (ASLE). The products of data of studied area were classified into four classes Fair, Poor, Very poor and Non agriculture according to fertility index, while studied previous was classified into three classes Fair, Poor, Very poor according to FI. Fertility index maps illustrate that some of the studied area have an increase in soil fertility and others have decline in soil fertility comparing with the previous study.

Moisture dynamics as related to capillary and drainable pores in the Nile Delta soils

Moisture dynamics as related to capillary and drainable pores in the Nile Delta soils

Effect of Biochar on Ammonia Volatilization in Saline-Alkali Soil

In order to investigate the effect of biochar on NH3 volatilization in saline-alkali soils of the Yellow River Delta, continuous laboratory incubation was conducted. Firstly, the recovery rate of NH3 volatilization by an improved aeration method was determined, the effects of fertilizer particles and aqueous fertilizer solution on NH3 volatilization were then compared. Finally, the effects of biochar species, application amount, and fertilizer type on NH3 volatilization rate and total amount were explored. The results showed that the average recovery rate of NH3 reached 100.30% using ammonium sulfate as the nitrogen source. With the same rate of nitrogen application, the volatilization of NH3 decreased by 60.29% in the treatment with urea as the aqueous solution compared to the treatment with urea particles, and decreased by 61.40% in the treatment with an ammonium sulfate aqueous solution compared to the treatment with ammonium sulfate particles. Compared with the control treatment (without the addition of biochar and with the addition of ammonium sulfate solution), the addition of 0.5% biochar derived from 300℃ rice biochar (RB-300), 600℃ rice biochar (RB-600), 300℃ cotton biochar (CB-300), and 600℃ cotton biochar (CB-600) reduced the total volatilization of NH3 by 18.68%, 16.16%, 9.35%, and 8.26% respectively. The volatilization rate of NH3 was at its highest within two days of fertilization, which accounted for 53.80%-64.02% of the total volatilization. After the addition of the biochar, volatilization of NH3 decreased at first and then increased in proportion to an increase in biochar content. Therefore, adding a small amount of biochar before field fertilization, combined with the integrated management of water and fertilizer, can effectively reduce NH3 volatilization and improve nitrogen use efficiency.

Response of Faba bean to alternate irrigation and cut-off irrigation combined with mineral phosphorus levels and Biofertilizer at North Nile Delta soils.

Response of Faba bean to alternate irrigation and cut-off irrigation combined with mineral phosphorus levels and Biofertilizer at North Nile Delta soils.

USE OF DRILL CUTTINGS ASH AS STABILISING AGENT FOR SELECTED NIGER DELTA SOILS FOR ROAD CONSTRUCTION

his study investigated potential of the use of Drill Cuttings Ash (DCA) in the stabilisation of Niger Delta soils for road construction. Most of the in-situ soils encountered in the region are fine-grained and highly plastic that would require special treatment. Four soil samples were obtained and the following tests were carried out: classification, compaction, California Bearing Ratio (CBR), and Unconfined Compressive strength (UCS). Dry DCA quantities ranging 2 – 8 percentages by weight of the soil was added to the air-dried soils for the stabilisation process. They were classified as A-6 (clayey soil), A-2-6 (clayey sand), A-3 (silty fine sand), and A-4 (silty clay soil). Generically, the unstabilised soils were fine-grained having low to medium plasticity, with low shear strength. Other results showed that 6% DCA content caused improvement in the texture, plasticity, and dry density of the clayey soil, while its CBR and UCS parameters compared favourably well with the unstabilised soil values. Also, there was increase in CBR value of the clayey soil after soaking for 24 hours. DCA increased the plasticity of the clayey sand, silty fine sand, and silty clay soil, and there was no substantial improvement in their strength properties. These results showed that DCA would be useful in improving clayey soilswhich are known to be prone to excessive swelling and difficult to handle during construction especially after heavy rainfall.&#x0D; &#x0D; &#x0D;

Potential health risks associated to heavy metal contamination of soils in the Yellow River Delta, China

The level of inhalable particulate matter (PM10) in the Yellow River Delta (YERD), an oil production area in north China, are generally high, resulting in an increase exposure to heavy metals (HMs) from soil. This exposure increases during winter and spring periods. In order to determine potential health risks posed by 9 HMs (i.e. Cr, Cd, As, Cu, Hg, Ni, Mn, Zn and Pb) in this area, high density sampling of surface soils across the YERD was undertaken. Results indicate that even through PM10 is generally high, no significant carcinogenic and non-carcinogenic health risks in YERD were identified. Ingestion rather than inhalation or dermal contact is the main exposure pathway. Hazard Index (HI) and total probability of carcinogenic risk (TCR) values indicated that children experienced higher carcinogenic and non-carcinogenic risks. Arsenic contributed the most to carcinogenic and non-carcinogenic health risks, while the effects of other HMs were minor. Our results also demonstrate that, based on the spatial trending of HI and TCR of high-risk areas, oil production will cause an unacceptable level of health risk. Due to the close proximity of this area to the coast, the wash effect of sea water will remove HMs from the soil and lower the health risks. Therefore, investigations related to coastal oilfields should investigate the transfer of HMs to seawater or local sediments. Our results provide a basis for environmental management in the YERD and other rapidly developing industrial regions around the world.

Retting and degumming of flax using biotechnology eco-friendly approach

Flax retting is a treatment process employed to dissolve or rot away much of the cellular tissues and pectins surrounding bast/fiber bundles thus facilitating separation of the fiber from the stem. The microbial retting is one of the most environmentally friendly process. The rich source of microbes contributing to flax retting is the retting water in commercial retting plants. The main objective of this work is to accelerate the flax retting using selected bacterial strains contributing to retting and degumming of flax in order to avoid chemicals causing environmental pollution. In this work, reuse of retting water for acceleration of flax retting was tested. The results show that, the reuse of retted water in new cycle of flax retting has accelerated the retting completion by 8.3-25% depending on the ratio of reused retted water in the retting liquor. Therefore, samples of flax straw retted water and soils from flax fields located in Nile Valley and Delta soils were collected for isolation of flax retting bacteria predominant in the retting effluents. Identification of the isolates was done using morphological, physiological and biochemical tests. Ten bacterial isolates were identified as Lactococcus cremoris, Chryseobacterium culicis, Serratia marcescens, Capnocytophage granulose, Micrococcus luteus, Enterobacter homraechei, Klebsiella oxytoca, Paenibacillus polymyxa, Proteus mirabilis and Bacillus humi. Three efficient strains in pectinase production necessary for flax retting were selected to test their role in enhancing the retting process. These strains are Bacillus humi, Chryseobacterium culicis and Micrococcus luteus which showed specific pectinase activity 37.17, 33.53 and 28 Umg1 respectively.The effect of these strains on retting duration and fiber quality were studied. The combinations of the three strains were tested in the lab scale cylindrical experimental bioreactor and each of the combinations was compared with the classical retting process of the industrial units. The combined treatment using strains: Chryseobacterium culicis, Micrococcus luteus and Bacillus humi resulted in the reduction of the retting duration by 30%, whereas, the mixed inocula containing Chryseobacterium culicis and Micrococcus luteus reduced the retting time by 25%. The mixture of Micrococcus luteus and Bacillus humi reduced the retting duration by 20%. The determination of weight loss, tensile strength, whiteness and yellowness of the fibers after microbial retting was monitored. These present study showed that the obtained specific bacterial strains enhanced the retting process.

Distribution and sources of polycyclic aromatic hydrocarbons in soils along the Shatt Al-Arab River Delta in southern Iraq

The soil samples from 0–10 cm depth were collected from three areas (Center of Basrah – CB, Garmat Ali – GA, and Abu Al-Khasib – AK) located along the Shatt Al-Arab River (SR) delta in southern Iraq to estimate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs). The PAH total concentrations in the soils decreased significantly from CB (72.16 ng/g dry weight (DW)), GA (36.48 ng/g DW), to AK (17.30 ng/g DW) gradually indicating the impact of pollution emissions on the distribution of PAHs in soils. The low (2 and 3 ring) and high (4, 5, and 6 ring) molecular weight PAHs accounted for 14%, 16%, 37%, 21%, and 12% respectively in CB soil, 24%, 31%, 29%, 7%, and 10% in GA soil and 40%, 29%, 17%, 8%, and 8% in AK soil. The high molecular weight PAHs predominated in CB soils and the low molecular weight PAHs dominated in GA and AK soils suggesting a difference in emission sources between the studied areas. The PAH diagnostic ratios and principal component analysis (PCA) indicated that PAHs in soils of the SR delta essentially originated from traffic and industrial emissions and biomass and grass/wood/coal combustion. The PAH atmospheric transport from CB area might impact the PAH distribution in the soils of AK area. The risk assessment of the soils has been performed. The total toxic equivalent concentrations (Bap&lt;sub&gt;teq&lt;/sub&gt;) of PAHs in the examined areas did not exceed the Dutch target values suggesting that no carcinogenic risk for the SR delta soils was found.

The effect of organic cosolvent and solute–solvent interaction on the solubility of oil residue in Niger Delta soil

The solubility of crude oil residue in contaminated soil ( $$ \log S_{\text{s}} $$ ) from six locations in the Niger Delta region of Nigeria in solvent has been determined by batch desorption technique using various fractions of water:methanol cosolvent mixtures (0, 0.2, 0.4, 0.6, and 1.0) and 100% (v/v) of four organic solvents (ethanol, dichloromethane, chloroform, and hexane). Data obtained from the experiment were applied to the solvophobic theory to evaluate the relationship between the solubility of the crude oil residue, solvent polarity, and the age of oil residue in the spilled site. Differences were observed between calculated and experimental values of solubility of oil residue in water ( $$ \log S_{\text{w}} $$ ) obtained for both old and younger oil residue, with higher values obtained for oil residue older than 5 years. Linear solvation energy relationship (LSER) using multiple-linear regression showed that the polarizability of the solvent (SP) was responsible for solute–solvent interaction. This ultimately leads to increased solubility of oil residue in the cosolvent ( $$ \log S_{\text{s}} $$ ) and dissolution of hydrophobic solute in water. Differences in Alip/Pol ratio between samples were attributed to the effect of aging on the oil residues. The correlated parameters allow an explanation of the main factors to consider when implementing the best technical option for crude oil-contaminated soil remediation by soil washing.

Effects of nitrogen and phosphorus on the production of carbon dioxide and nitrous oxide in salt-affected soils under different vegetation communities

Nutrient availability greatly regulates ecosystem processes in salt-affected soils. However, few studies have explored the impacts of nitrogen (N), phosphorus (P) and N × P interactions on CO2 and N2O emissions from salt-affected soils in the Yellow River Delta (YRD), which is one of the three biggest deltas in China. An incubation study was conducted to test the effects of N or P addition alone, as well as combined NP application, on CO2 and N2O emissions from the soils taken from four sites: bare land (BL) with no vegetation cover and three adjacent vegetation communities, Tamarix chinensis (TC), Suaeda salsa (SS) and Phragmites australis (PA) in the YRD. The results showed that N and its interaction with P showed significant and identical effects on both CO2 and N2O emissions in all soils. Nevertheless, the significant effect of P on CO2 production was found in soils covered with vegetation. N addition tended to augment CO2 and N2O emissions. However, the significant positive correlation between cumulative CO2 emissions and P addition was only found in soils collected from different communities. Compared with soils collected from BL, soils from different vegetation communities emitted more CO2 and more N2O. Moreover, soils of woody communities produced more CO2 than those of herbaceous communities. On the contrary, N2O emissions in soils of herbaceous communities were higher than in woody communities. Therefore, more attention, should be paid to the pulse GHG emissions that result from nutrient addition during the reclamation of saline soils, especially those covered with vegetation.

Source quantification and potential risk of mercury, cadmium, arsenic, lead, and chromium in farmland soils of Yellow River Delta

Accumulation of pollutants, especially heavy metals in river delta systems, pose a severe threat to the ecological environment and also hinder sustainable development of deltas. A total of 390 samples were collected from farmlands throughout the Yellow River Delta (YRD), the fastest growing delta in the world, to explore the holistic distribution characteristics and restrictive environmental factors of mercury (Hg), cadmium (Cd), arsenic (As), lead (Pb), and chromium (Cr) in the soil. Results indicated that soils in farmlands at the YRD had relatively low average concentrations of selected elements with non-contamination level. This is due to low elemental contents of loess parent materials and less human activities. These elements in soils had distinct spatial distributions and disparities from different categories, which were predominately determined by soil physicochemical properties such as cation exchange capacity, organic matter content, clay fraction and soil acidity. Sodium salt played a vital role in this delta for soil salinization. Agricultural inputs, industrial emissions, and river suspended sediments were the three primary sources of these elements. Of these elements, 65% of Hg came from atmospheric deposition, 66% of Cd was sourced from industrial emissions, 53% of As and 46% of Pb originated from agricultural inputs, and 64% of Cr was rooted from parent materials. Based on these findings, critical strategies including controlling the agrochemical input and removing industrial pollutant emission were proposed for sustainable development of the YRD.

Encapsulation of lead in rice phytoliths as a possible pollutant source in paddy soils

Due to its serious health risks, lead (Pb) in rice, specifically its uptake, translocation, and accumulation mechanisms and its toxic effects have been studied intensively in recent years. However, it remains unclear about the role of phytolith, a siliceous structure in rice plants, in the storage and release kinetics of Pb in rice. This study aims at elucidating a possible encapsulation of Pb in the phytolith structure (phytPb), and identifying whether or not phytPb provides a source of Pb in soil, when returned to the field with the rice straw or in a related processed product such as ash from on-site burning. To date there has not been any specific work targeted at the determination of phytolith-associated heavy metals in general and phytPb in particular, and therefore this possible source of Pb in soils may have been overlooked. Phytoliths were included in a study of rice paddy soil and rice straw to demonstrate accumulation of phytolith and its associated phytPb in agricultural soils of the Red River Delta (Vietnam). The total content of Pb in rice straw samples was found to be up to 118 mg kg−1, and this Pb sink can be cycled to serve as a new Pb source in soils. The fate of Pb in rice straw might be directly related to open burning activity (a common practice in the Red River Delta), in which volatilization or sub-compartmentation in slagged phytolith appeared as controlled factors. This is supported by the findings from batch experiments for rice straw ash samples, in which release of Pb was low and a portion of Pb in rice straw were found to associate with phytolith structural organic matter. We also observed the presence of phytPb in "aged" phytolith fragments which had accumulated in the paddy field soil. However this Pb pool was relatively low (from 7.8 to 34 kg ha−1) relative to other soil Pb fractions. As the thermal treatments of Pb-tainted rice straw resulted in losses of Pb via volatilization, open-field burning practices for Pb-contaminated rice straw is suggested as an environmental risk.

Effect of saline intrusion on the properties of cohesive soils in the Red River Delta, Vietnam

This study conducted a series of laboratory experiments and established numerical models on selected undisturbed soil samples in the Red River Delta (RRD) to determine the effect of change in soils intruded by saline water. The variation in the technical parameters of soils was verified in soils fully saturated by solution of four salt concentrations, that is, 0.0, 9.9, 19.8, and 33.0 g/L. Results show that the content and composition of clay minerals in cohesive soils before and after saline intrusion are unchanged. The same finding is obtained for clay after removing absorbed water layer by using a centrifuge apparatus. The zeta potential and settlement velocity of soils in the RRD increase when salt is added to the saturated solution. Similarly, the deformation of soils increases proportionally with the salt concentrations of that solution. This result is attributed to the linear decrease in deformation modulus. The decrease in modulus versus salinities is nearly consistent for pressure stages from 100 to 400 kPa. The safety factor of bearing capacity also decreases linearly with salinities. The decrease reaches 12.5–16.3% when soils are in the maximum saline solution. All these changes are considered as the degradation of soils in saline media.

Editorial for pedometrics 2017 special issue

Editorial for pedometrics 2017 special issue

Microbiological Characteristics of Soils of the Upper Delta of the Selenga River under Arid Conditions (Baikal Region)

The abundance, ratio of ecologo-trophic groups of microorganisms, microbial biomass, and predominant members of the taxonomic composition of microbial complexes are indicators of the different ecological states of soils of the central floodplain and islands of the upper delta of the Selenga River under arid conditions. The highest coefficients of oligotrophy with an increased share of microorganisms growing on the nitrogen-free Ashby medium, as well as predominance of Arthrobacter bacteria, were determined in low-moistened soils of the islands. In general, low microbiological activity (in comparison with the soils of the central floodplain depressions), resulting from a lack of moisture, is observed in these soils despite the uncontrolled cattle grazing in the areas of the latter.

Soil Moisture Sensor Test with Mississippi Delta Soils

Abstract. One of the methods for irrigation scheduling is to use sensors to measure the soil moisture level in the plant root zone and apply water if there is a water shortage for the plants. The measurement accuracy and reliability of the soil moisture sensors are critical for sensor-based irrigation management. This study evaluated the measurement accuracy and repeatability of the EC-5 and 5TM soil volumetric water content (SVWC) sensors, the MPS-2 and 200SS soil water potential (SWP) sensors, and the 200TS soil temperature sensor. Six 183 cm × 183 cm × 71 cm wooden compartments were built inside a greenhouse, and each compartment was filled with one type of soil from the Mississippi Delta. A total of 66 sensors with 18 data loggers were installed in the soil compartments to measure SVWC, SWP, and soil temperature. Soil samples were periodically collected from the compartments to determine SVWC using the gravimetric method. SVWC measured by the sensors was compared with that determined by the gravimetric method. The SVWC readings from the sensors had a linear regression relationship with the gravimetric SVWC (r2 = 0.82). This relationship was used to calibrate the sensor readings. The SVWC and SWP sensors could detect the general trend of soil moisture changes. However, their measurements varied significantly among the sensors. To obtain accurate absolute soil moisture measurements, the sensors require individual and soil-specific calibration. The 5TM, MPS-2, and 200TS sensors performed well in soil temperature measurement tests. Individual temperature readings from these sensors were very close to the mean of all sensor readings. Keywords: Irrigation, Sensors, Soil types, Soil water content, Soil water potential.

Strain rate effects on soil-geosynthetic interaction in fine-grained soil

Izmir Bay reserves high amount of residual alluvial deposits generated by Meles River at its stream mouth. These carried sediments with high water content and low bearing capacity are unsuitable in terms of engineering purposes. In-situ soil stabilization with deep soil mixing method is considered to improve properties of soil in this location. This method is widely used especially over Scandinavia, Japan and North America. Basically, the method covers mixing appropriate binder into the soil to improve soil profile according to the engineering needs. For this purpose, soil samples were initially provided from the site, classification tests were performed and optimum ratios of lime and cement binders were determined. Following, specimens representing the in-situ soil conditions were prepared and cured to be able to determine their engineering properties. Unconfined compression tests and vane shear tests were applied to evaluate the stabilization performance of binders on samples with different curing periods. Scanning electron microscope was used to observe time-dependent bonding progress of binders in order to validate the results. Utilization of 4% lime and 4% cement mixture for the long-term performance and 8% lime and 8% cement mixture for short term performance were suggested for the stabilization of Meles Delta soils. Development of CSH and CAH in a gel form as well as CSH crystals were clearly observed on SEM images of treated specimens.

Soybean Irrigation Initiation in Mississippi: Yield, Soil Moisture, and Economic Response

Abstract. Irrigated acreage is expanding and groundwater supplies are decreasing in the Mississippi Delta. Efficient irrigation scheduling of soybean [ (L.) Merr] will aid in conservation efforts to sustain groundwater resources. The objective of this study was to develop irrigation initiation recommendations for soybean grown on Mississippi Delta soils. Field studies were conducted on a deep silty clay (SiC) in 2012, 2013, 2014, and 2015 and on a deep silty clay loam (SiCL) and deep silt loam (SiL) or loam (L) soil in 2013, 2014, and 2015. Irrigation was initiated multiple times during the growing season and soybean yield and net return were determined to evaluate the effectiveness of each initiation timing. Growth stage, soil water potential (SWP), and soil water deficit (SWD) were compared at these initiation timings to determine which parameter or combination of parameters consistently predicted the resulting greatest yields and net returns. Stress conditions that reduce yield can occur at any time from late vegetative stages to full seed on these deep soils. The wide range of trigger values found for SWP and SWD to increase yields in different years emphasizes the complexity of irrigation scheduling. Monitoring soil moisture by itself or use of a single trigger value is not sufficient to optimize irrigation scheduling to maximize soybean yield with the least amount of water every year on these soils. Monitoring one or more parameters (e.g., leaf water potential, canopy temperature, air temperature, humidity, solar radiation, and wind) is needed in conjunction with soil moisture to directly or indirectly quantify the abiotic stresses on the plant to better define when a yield reducing stress is occurring. Keywords: Irrigation initiation, Irrigation scheduling, Soil water deficit, Soil water potential, Soybean, Water conservation.