Journal of Dry land Soil Research
Volume:1 Issue: 1, Summer 2024

The sustainability production of dryland agriculture is threatened by salt accumulation in soil due to irrigation practices by saline waters. However, the dynamic processes of secondary soil salinization depend on some factors varying in time and space. The aim of this research was to introduce an approach for the prediction of soil salinity in some irrigated pistachio (Pistacia vera L.) orchards facing secondary soil salinization. The study area was Ardakan (Yazd Province, Central Iran). In this approach, the Landsat 8 satellite data bands and satellite–based driven data (indices) were used. The Partial Least Square Regression (PLSR) method was used to predict the variability of soil salinity with minimum (zero) ground measurements. The predicted soil salinity (electrical conductivity) of soil saturated paste extract (ECe) were compared by the measured ECe. The existing conventional methods (e.g. WatSuit computation model) using ancillary measured data of irrigation water salinity (ECiw) and corresponding leaching fractions (LF) were also used for evaluation. The Results of the satellite-based PLSR method showed an R2 of about 64% between predicted and measured soil salinity, while this indicator was about 72% for the conventional model of WatSuit. The higher accuracy of the Watsuit model is owing to its dependence on ground measurements, while the introduced satellite-based PLSR approach was able to predict temporal changes of soil salinity in patterns fitted to the irrigation intervals with zero dependence on the ground truth data.

Extreme floods are able to execute river geomorphological variations with a wide and substantial geological changes. Former studies of extreme floods have reported a reach of geomorphic replies from negligible change to catastrophic channel change. This article provides an evaluation of the geomorphic effects of a scarce, great value event that occurred in the Ilam Dam upstearim, on 29 October 2015. Variations in geomorphic replies among reaches are examined in the context of changes in flood power, channel competence and lateral confinement index by the use of field survey and Satellite Images (IRS). In this research which is focused on the plan of spatial units, channel width variations and calculation of peak discharges were used to estimate cross-sectional stream power and unit stream power. The analysis was performed for the widening (width ratio) at reach scale. The total data set includes 38 reaches. Because of the 2015 flood, the largest value of widening was 29 m (Reach 13) and it demonstrated a 100% change in the channel width. Flood power peak was calculated 10631 W m−2 along the rather confined reaches (Reach 31) and was much lower along the unconfined reaches. The tendency of high stream power values, and resultant high erosion rates, within the confined and partly confined reaches is a subordinate of the higher energy slope of the steeper.

Textural components of soil play an essential role in erodibility and should be considered in many projects of conservation and environmental modeling processes. Traditional methods of determining soil texture are usually laborious, expensive and time consuming along with destructive effects on the environment. Meanwhile, spectroscopic technology using the spectral features and signatures from the whole reflected spectra of soil surface promises a competent method to study soil constituents. To investigate this issue, 113 points were selected and sampled randomly from 0-15 cm of soil surface in eastern parts of Mazandaran Province, Iran. Samples were haphazardly divided into 91 for model building and 22 for final verification and accuracy assessment processes. Applying the enhanced PLS-algorithm plus the FLOOCV approach along with spectral transformations and pre-processing, the modeling of each textural components were accomplished. Spectrally, sand and clay fractions were modeled with high accuracy as: R2c= 0.89, RMSEc= 7.42, SEc= 7.46 for sand and R2c= 0.82, RMSEc= 6.88, SEc= 6.92 for the clay content. Whereas, the silt predictive model was slightly weaker than the other constituents. The most effective spectral ranges involved in the modeling process, were also detected and recognized based on beta & spectral weight analyses and Marten’s uncertainty test. Additionally, the most influential spectroscopic ranges included were the visible, NIR and SWIR regions with the specified wavelengths. In general, the efficacy of spectroscopic technology in soil texture studies has been proven by this research. Using the computed spectral models, we are able to study the soil textural components at large scales faster, safer, timelier and also cheaper. That is absolutely true and applicable using the regionalized remotely sensed data but requires further investigation in different geographical regions.

One of the main ecosystem services of mangroves is enhancing carbon sequestration, most of which is done by sediments. Therefore, recognizing sediment properties is useful to evaluate the factors affecting carbon uptake in mangrove sediments. To identify the relationship between sediment organic carbon (SOC) content and sediment properties, sampling from three mangrove forests in Bushehr (Iran) coastal regions (Asalouyeh, Basatin, and Malegonzeh) was performed at 6 different stations, and the SOC of the samples were measured by Walkley and Black method. The particle diameters were performed by the sieving and hydrometer method and the results were analyzed (Gradistat. v8). The results showed that the highest percent of particles were silt, ranging from 93.6 to 96.6%. Several sediment grain size properties were correlated with SOC. Two factors were analyzed in principal component analyses, which were responsible for 75.8% of the samples attrinbutes. Factor 1 was organic carbon (SOC), skewness, sand, mean size, sediment density, clay, and silt summation (clay & silt). Factor 2 included clay, sorting, and kurtosis. Organic carbon was positively correlated to sorting, clay & silt percent, and grain size (ɸ). Meanwhile, the SOC was negatively correlated to sediment density, C, sand percent, and skewness. Generally, by decreasing the size of the sediment particles, the amount of SOC increased. Areas with fine-grained sediments appear to be able to absorb more organic carbon.

One of the main causes of soil pollution is the release of crude oil into the environment. Indigenous microorganisms with the capability of biodegrading hydrocarbon components can be used to improve the efficiency of microbial bioremediation technology. Here, oil-contaminated soils were collected from five oil refineries (Abadan, Isfahan, Tehran, Tabriz and Shiraz) for screening and isolation of geographically adaptive indigenous oil-degrading bacteria. Bacterial colonies from oil-contaminated soil samples were isolated, which were able to grow in a medium containing crude oil, light, and heavy diesel, as a sole carbon source. Twelve strains were isolated, purified, and identified, using the 16S rRNA gene sequencing analysis. The isolates belonged to five species, including Achromobacter spanius, Klebsiella quasipneumoniae, Ochrobactrum intermedium, Citrobacter amalonaticus, Pseudomonas aeruginosa. These bacterial strains were capable of growing in media containing crude oil, light and heavy diesel for 7 to 9 days and had the potential for biosurfactant production. These bacterial strains can be considered as geographically adaptive bacteria, creating preliminary data for further research to utilize their bioremediation potential.

In this study, total petroleum hydrocarbons (TPHs) decontaminating mechanisms for soils around the Rey refinery complex (South of Tehran, Iran) was investigated. Natural attenuation, biostimulation and bioaugmentation (separately and in combination) methods were evaluated TPHs and soil microbial respiration in 210 days, using laboratory treatments The modified methods were applied through 13 different treatments, including improving the environmental conditions for native bacteria (natural attenuation for treatments 1-8), adding non-native bacterial complex (bioaugmentation for treatment 9) and intensifying and stimulating growth while adding non-native bacterial complex (biostimulation-bioaugmentation for treatments 10-13). Although, overall of the treatments, a significant decreasing TPHs concentration were observed over the time, biostimulation-bioaugmentation treatments had the highest amount of TPHs decomposition, the highest rate of bio-respiration, the lowest half-life times (t1/2), and the highest remediation efficiency and biodegradation constants rate. Among natural attenuation treatments, modifiers with manure and sawdust had the greatest effect on reducing the TPHs concentration and the highest rate of bio-respiration. The first-order kinetic model was fitted to the data related to biodegradation in a satisfactory manner. The results showed that there was a strong and positive linear correlation between decreasing TPHs concentration and microbial respiration in all modifiers. Although for the bacterial treatments and at the early stages of inoculation, the rate of total respiration was low, but as the time passed and with adaptation of the effective inoculated bacteria to contaminated soil, the respiration rate gradually was increased. Due to its low cost and low environmental risk, the proposed bioremediation technique for oil contaminated soil can be recommended to the region.

Very few studies have investigated the effects of crop morphological characteristics on soil loss due to crop harvest (SLCH). The present study investigates the soil, nutrient (nitrogen, N, phosphorus, P, and potassium, K), and organic carbon losses during the harvest of different potato cultivars with different morphological characteristics. The experiment is conducted at different soil water contents (SWC) controlled by different irrigation schemes, with the last irrigation 5, 10, and 15 days before harvest. At harvest time (early fall), in addition to measuring tuber yield (which was harvested manually) and SLCH, disturbed and undisturbed soil samples were collected in the field to measure various soil physicochemical properties and soil nutrient contents exported from the field. On average, 0.79 ± 0.36 Mg ha-1 soil, 580 g ha-1 nitrogen, 3 g ha-1 extractable phosphorus, 350 g ha-1 potassium, and 4.2 Kg ha-1 organic carbon were lost from the experimental fields at each harvest. The SLCH of the farms with Fontane, Challenger, and Agria cultivars was 1.21 ± 0.03 Mg ha-1 harvest-1, which was about three times higher than the SLCH of the farms with Innovator, Banba, Red Scarlet, Sifra, and Arinda cultivars with an average SLCH of 0.46 ± 0.06 Mg ha-1 harvest-1. The highest SLCH (2.57 Mg ha-1) occurred when SWC was highest compared to the other SWC values (i.e., 0.42 Mg ha-1). For a given soil stickiness, tuber length and specific surface area (SSA) generally explained the variation in SLCH values, with elongated tubers having lower SSA resulting in lower SLCH values.

The confined compression curve (CCC) of soil and its parameters reflect the impact of management operations such as tillage, cover crops, and intercropping on the physical and mechanical properties of the soil. No research has investigated the simultaneous effect of these three factors on the CCC. Therefore, the effects of two different tillage systems, moldboard plowing (MP, conventional tillage) and chisel plowing (CP, reduced tillage), combined with cover crop (CC) and without cover crop (NC) (i.e., planting Lathyrus sativus as/without cover crop) and three cropping systems (summer squash (Cucurbita pepo), green bean (Phaseolus vulgaris), and their intercropping) were investigated on soil compaction characteristics. Next, the CCC of the soil was measured, and its parameters were derived. In MP-CC treatment compared to MP-NC, the compression index (0.43) decreased and pre-compression stress increased by 19%. The low organic matter in NC-summer squash treatment reduced the swelling index (soil mechanical resilience) compared to other treatments in the ranges of 4.76-33%. Besides, MP increased the loading swelling index compared to CP by 33%. Overall, the best management was the application of the CP-CC under intercropping of summer squash with green beans because it reduced the soil compaction. Moreover, CP improved the soil’s physical-mechanical properties.

This study was designed due to the appearance of some oil pollution signs around the Sarkhun gas refinery in the city of Bandar Abbas and provided a comprehensive assessment of the current location of hydrocarbon pollution, evaluating some important pollution factors and predicting pollution distribution in the soil around the refinery. Soil samples were taken from different layers, then TOG (Total Oil and Grease) and TPH (Total Petroleum Hydrocarbon) were measured. Total suspended and soluble solids, the amount of initial oil input, and chemical and biochemical oxygen demand were evaluated. Vertical and horizontal pollutants seepages were prepared by Surfer, ArcGIS, and MATLAB. The novelty of this study was a prediction of the release of condensate gas in a specific area (depth of 24 meters of groundwater and the presence of hard surface layers). The results showed that the pollution mostly occurred in the north side of the refinery and TOG and TPH confines from 3633 and 2612 (burning pits) to 7 and 4 mg/Kg soil (south-west of the refinery) respectively, along the slope of the earth layers with more tendencies to Shour river. Abrupt increasing pollution in the east part of the refinery was attributed to the previous breakage of the sewer pipe. The results showed that the deep infiltration was up to the dimensionless depth of 0.2 and in more depth, reduced noticeably. Furthermore, TOG showed severity spreading against TPH in a similar direction. The simulation results showed that by increasing the entering water debit to burning pits, pollution spreading risk will increase, so preventing the pollution extension must be considered.

Soil erosion and sediment yield in the downstream areas, water transfer canals, and dams are the most serious problems in the world today. Soil erosion threatens soil resources, causes severe damage to infrastructures, and imposes high costs on agriculture, watershed management, and natural resources. Reducing these hazards and damages due to soil erosion and sediment yield requires the use of quantitative data to identify critical areas that require immediate protection. Due to the high cost and time consuming of conventional methods, the use of new remote sensing technologies and satellite imagery is essential. This study used the MPSIAC model, one of the most well-known models for estimating soil erosion and sediment yield in Iran, geographical information system (GIS), and satellite image processing with object-oriented and pixel-based methods. For this purpose, basic data were prepared using base maps, Sentinel-2 satellite imagery, meteorological and hydrometric data, and fieldwork. After establishing a database, the score for each of the nine factors of the MPSIAC model was determined using the three common, object-oriented, and pixel-based processing methods. The extent of soil erosion and sediment yield of the watershed was determined within each hydrologic unit. Based on the results, the soil erosion and sediment yield intensities of the Lighvan watershed were classified as medium class (III). However, the comparison of the specific soil erosion and sediment yield values obtained from the three methods showed that the use of object-oriented methods in determining the values for land cover, land use, and current soil erosion state increased the accuracy of the predictions (with the estimated error of 12.18% and 13.15% for sediment yield and erosion, respectively) compared to common (with the estimated error of 15.73% and 16.71%) and pixel-based (with the estimated error of 18.78% and 19.45%) methods.

Ammonium acetate (NH4C2H3O2) is the extractant mostly used by the local soil laboratories in Iran when determining available potassium (Kava) in calcareous soils. To optimize the procedures for determining soil available potassium (Kava), two individual experiments were carried out.For this purpose, the effect of two NH4OAc concentrations (i.e., 1 M and 0.1 M NH4OAc) and  the efficiency of two extraction procedures (i.e., 30 min shaking on the orbital shaker and keeping the mixture overnight (12 h) without shaking) were investigated. Calcareous soils (1234 samples) from different parts of Iranian provinces were collected. The results revealed that in most soils, the decrease in the NH4OAc concentration from 1 to 0.1 M had no significant effect on the Kava concentration. There was a significant and positive correlation between potassium concentrations of 1 and 0.1 M NH4OAc extractants, although, a significant deviation was observed for some soils. The regression equation between the two extractants was y = 0.97 x + 8.43 (R2 = 0.97 and SEE = 36.5), which overlaps with the 1:1 line. Therefore, to save the chemicals and reduce analysis costs, 0.1 M NH4OAc can be used instead of 1 M NH4OAc. Results obtained from the second experiment clearly showed that shaking the mixture for 30 min was as effective as keeping it overnight without shaking to 30 min with shaking in extracting soil available potassium.

Plum is an important stone fruit of Pakistan. The productivity of plum orchards in Pakistan is very low, particularly owing to the unbalanced and untimely application of fertilizer and irrigation by the farmers. Fertigation is a technique in which dissolved fertilizers are used for crops together with an irrigation system. Combined application of nutrients and water with an efficient irrigation system can result in the maximum possible yield and quality of plants. A two-year field experiment in Peshawar, Pakistan was conducted during 2018-2020 to evaluate the effect of fertigation of different rates of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on yield and quality of plum. Fruit-bearing plum orchards of uniform age and size were selected. The treatments included T1 (control), T2 (NPK @ 360-250-360 g tree-1 applied as broadcast), T3 (NPK @ 360-250-360 g tree-1 applied as fertigation), T4 (270-187-270 g tree-1 applied as fertigation) and T5 (NPK @ 180-125-180 g tree-1 applied as fertigation). All the fertilizers were applied to the periphery of the plum tree canopy. The yield and fruit concentration of N, P, and K were significantly (P<0.05) improved in the treatments where nutrients were applied as fertigation as compared to those where fertilizers were applied as broadcast. Plum fruit yield was recorded as maximum (90.1 kg plant-1) when NPK @ 180-125-180 g tree-1 was applied as fertigation. Similarly, maximum N (0.56%), P (0.19%), and K (1.53%) concentrations as well as the highest value cost ratio (101.3) were obtained by the application of NPK @ 180-125-180 g tree-1 as fertigation.