JWSS - Journal of Water and Soil Science

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In order to compare the effect of drip and furrow irrigation methods with different quantities of water (50%, 75%, and 100% of the amount of water evaporated from class A pan evaporation during irrigation intervals) on yield and quality of tomato, an experiment was conducted on a silty loam soil in Mashhad Agricultural Research Station. The experimental design was a factorial trial with completely randomized blocks and. four replications.

The results showed that the highest yield (51 t/ha) was obtained from the treatment of drip irrigation with 100% water application. This amount was 4.5 tons higher than the yield from furrow irrigation treatment. Deficit irrigation by 25 and 50 percent decreased total yield by 34.7% and 67.95% in the drip irrigation method and by 27.57% and 64.29% in the furrow irrigation, respectively. Water use efficiency in drip irrigation was two times higher than that in the furrow treatment. Quality and chemical composition of the fruits were not significantly different in the two irrigation methods. Increasing the water deficit, however, increased the amount of soluble solids of the fruits.

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A field study was conducted at the College of Agriculture, Ferdowsi University of Mashhad, to investigate the effect of irrigation with treated municipal wastewater on the yield and quality of lettuce and some soil characteristics. Five irrigation treatments were applied to a clay loam soil, classified as fine loamy mixed mesic Calcixerollic Xerochrepts, in a randomized block design with 5 replications. The treatments consisted of T1 (Irrigation with treated wastewater over all growing season), T2 (Alternate irrigation with treated wastewater and well water), T3 (Irrigation with well water and application of cattle manure), T4 (Irrigation with well water plus fertilizer N and P), and T5 (Irrigation with well water only as control). Chemical analysis of well water proved to be a suitable source for agriculture.

The results showed that the yield was higher in T1, T2, T3 and T4 as compared to the control treatment. Maximum fresh and dry yields were obtained from T3 & T1 and T1 & T3, respectively. Plant tissue analysis showed an increase in macronutrients (N, P, K) and heavy metal concentrations in shoots and roots of lettuce in the first four treatments as compared to the control. In T1, iron concentration was maximum while that of cadmium was minimum. Furthermore, microbial contamination was considerably higher in T1 and T2. Soil analysis indicated that in plots treated with wastewater, electrical conductivity, total nitrogen, available phosphorus, soluble boron and heavy metal concentration increased. However, their values were all below international standards. More experiments seem to be necessary in this regard.

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The presence of large amounts of calcium in the equilibrium system of calcareous soils of arid and semi-arid regions affects the chemical reactions of soluble and exchangeable phases. Exchange phenomenon is one of these chemical reactions in which calcium plays an important role. K-Ca equilibria are important equilibria in calcareous soils and may be an answer to many problems in soil chemistry and fertility, specifically on the availability of potassium. Little work of this nature has been done in Iran. In this work, a variety of calcareous soil samples from northern Khorasan were examined. First, regression equation between potassium adsorption ratio (KAR) and exchangeable potassium ratio (EKR) in 26 soil samples was found to be EKR=0.02+2.48KAR, R²=0.77. Gapon exchange selectivity coefficient (K_G) was estimated as 2.48 for the soils. Furthermore, in 14 calcium saturated soil samples, different concentrations of K were added until equilibrium was reached and EKR and KAR relations were determined for each soil with a regression coefficient higher than 0.91. K_G ranged between 1.21 to 3.34. For the potassium range used in the soils studied, K_G was constant and almost matched the KG obtained from EKR and KAR relation of the first step. Based on this equation, the effect of soluble K on exchange K in the presence of Ca and Mg as dominant cations in calcareous soils may be evaluated.

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Of all types of xenobiotics, pesticides such as herbicides play a significant role in soil and water pollution due to their widely usage all over the world. This study addresses the ability of organic amendments to enhance atrazine and metamitron degradation in two herbicide contaminated soils with contrasting textures under laboratory conditions. Soil samples were collected from surface soils with textures of sandy loam and silty clay, from northeastern part of Iran. Initial concentration of herbicides was 50 mgkg^-1 soil. Contaminated soil samples were treated by manure, compost and vermicompost at the rates of %0.5 and %2 (w/w). Residual concentrations of atrazine and metamitron were determined by HPLC at the end of incubation periods of 20,40 and 60 d. Residual concentrations of atrazine were 93, 77.8 and 72.4 % of the initial concentration after 20, 40 and 60d incubation, respectively. Residual metamitron concentrations were clearly lower than atrazine. After 20,40 and 60 d., the remaining concentrations of metamitron were 5.8, 2 and 1.2 %, respectively. Organic amendments at the rates of .5 and 2 % showed similar effects on the enhancement of herbicides degradation in soils. However, no significant effect was observed between types of organic amendments. Degradation was clearly affected by soil textures. Residual concentrations of herbicides were higher in sandy loam than in silty clay soil.

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Study of phosphorus reactions over time and the role of organic matter in the calcareous soils are important for the development of P fertilizer and manure management practices. The objective of this study was to determine the effect of applied manure on P availability and its chemical forms in the soil, over time. Eight samples were collected from semi-arid calcareous soils of Mashhad plain. The samples were treated with two levels of inorganic P (0 and 300 mg P kg^-1 soil as KH₂PO₄) and two levels of organic matter (0 and 1% cattle manure). The experiment was conducted in a completely randomized design with factorial arrangement. The treated soil samples were incubated for 2, 5, 10, 30, 60, 90 and 150 days, then analyzed for available P (Olsen-P). The result showed that only 17% of added phosphorus was available in P treatment at the end of experiment. In manure treated soils, this figure reached 34% for the same period of time. Application of manure along with P increased the recovery of applied P and CBD-P (Citrate-Bicarbonate-Dithionite). This may be due to the formation of P-organic complexes with Fe oxides. Application of manure in soil increased NaCl-NaOH-P considerably compared with P and P+OM treatments. It can be concluded that P originating from manure compared with inorganic-P may be more available for plants over the time.

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  It is important to investigate the genetic diversity and evaluate symbiotic effectiveness of the indigenous rhizobial population. It helps understand the responses of indigenous isolates to different rhizobial inoculants. In spite of the importance of bacterial diversity, there are a few scientific reports about it in Iranian soils. Genetic diversity of 150 isolates of Sinorhizobium isolated from Hamadan soils was studied by using PCR / RFLP 16S-23S rDNA technique. The results showed that all isolates clustered in three different groups. Group (I) formed 122 isolates and they were quite similar to Sinorhizobium meliloti from viewpoint of genetic characteristics. Twenty five isolates were clustered in Group (II) and they belonged to Sinorhizobium medicae. Group (III) had two isolates and they were new species and quite different from the other groups. Shannon diversity index was different within eleven different land units (Medium gradient mountains, Level lands, Plateau, Foot slopes, Depressions and Composite land) and there was a correlation between Shannon index and some soil properties. Difference in Similarity index showed that Sinorhizobium groups in each land unit were different.

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This study was conducted to compare the impact of various organic amendments with different C/N ratios and chemical compositions on biological and chemical degradation of Atrazine in sterile and non-sterile soils. The experiment was carried out in a factorial arrangement (2×6×2) including two soil types (sterile and non sterile soils), six types of organic amendments (vermicompost, cow manure, glucose, starch and sawdust and without organic matter) and two levels of inorganic nitrogen fertilizer (0 and 250 mg kg-1), with three replications. Initial Atrazine concentration in soil samples (silty loam) was adjusted at 100 mg.kg-1. Soil samples were amended by organic materials at the rate of 5% by weight and treated with 250 mg inorganic nitrogen fertilizer( NH4NO3). Half of soil samples were sterilized by HgCl2. Residual Atrazine concentration in soil samples were determined by HPLC at the end of 20, 40 and 60 days incubation time. The results showed that all the applied organic amendments (except for cow manure) and inorganic nitrogen treatment reduced biological degradation of Atrazine in non- sterile soil samples. It was not possible to predict the biological degradation of Atrazine based on C/N ratio of organic amendments and microbial activity. The results also showed that chemical degradation of Atrazine after 60 days of incubation was not affected by organic amendment and inorganic nitrogen fertilizer.

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The contamination of soils with lead is a major environmental problem throughout the world. Phytoextraction of heavy metals from contaminated soils has the prospect of being a more economic in situ alternative. Chemically enhanced phytoextraction has been proposed as an effective approach to remove heavy metals from contaminated soil through the use of high biomass plants. Using a pot experiment, the effects of the application of three rates of EDTA at 0, 1.5 and 3 mmol/kg soil and sulfuric acid at 0, 0.5 and 1 mmol/kg soil with two rates of Pb at 0 and 200 mmol.kg-1 on the uptake of Pb by corn (Zea mays L. single cross 704 var.), sunflower (Helianthus annuus L. ajili var.), and cotton (Gossypium hirsutum L. varamin var.) plants were studied. The results showed that EDTA was more effective than sulfuric acid in increasing the concentration of Pb in shoots and roots for all plants studied. The maximum amount with application of EDTA to soil for shoots of corn, sunflower, and cotton were 4.07, 6.49 and 31.33 times higher than the control, respectively. EDTA also enhanced Pb content of roots of corn, sunflower, and cotton 3.38, 1.63 and 1.09 times higher than the control, respectively. DTPA-Pb was higher in soil treated with EDTA than sulfuric acid. The application of EDTA also significantly increased shoot-to-root ratio of Pb in plants examined. The results of this study showed that corn was able to phytoextract more Pb than sunflower and cotton.

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Silver toxicity and its fate in the environment are currently being debated and are important as challenging research topics. Even though there are several studies on its total content in soils, fractionation of Ag especially in calcareous soils has not been investigated. Therefore, to provide fundamental information on the chemical behavior of Ag in calcareous and noncalcareous soils, we studied 8-step chemical fractions of Ag (i.e., EXCH, CARB, Me-Org, re-MeOx, H2O2-Org, am-MeOx, cr-FeOx, and RES) after 30 and 60 days of incubation in soils amended with Ag (0 and 15 mg kg-1), sewage sludge (0 and 20 t ha-1) and EDTA (0 and 0.5%). Experimental results showed that redistribution of Ag in spiked noncalcareous soils was EXCH (34%), H2O2-Org (33%) and RES (17%). In calcareous soils, after 30 days, EXCH- and RES-Ag increased but at the end of 60 days H2O2-Org-Ag increased. Based on our data, we could conclude that addition of Ag results in an increase of Ag mobility in soils but incubation and sewage sludge may have adverse effect on its mobility. In contrast to noncalcareous soil, EDTA in calcareous soil resulted in higher Ag mobility. This may have environmental implications in Ag polluted calcareous soils.

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Mycorrhizal fungus colonization of roots may modify plant metal acquisition. In order to study the role of external hyphae of mycorrhizal fungi in metals transferring, the root and hyphal growth zone were separated by 30 µm nylon meshes. Plants were inoculated with G. mosseae and G. intraradices and grown in the root compartment. Six combinations of metals (400 mg of Zn, 25 mg of Cd, 400 mg of Zn + 25 mg of Cd, 50 mg P, 50 mg of P+ 400 mg of Zn + 25 mg of Cd, and no metal kg-1 soil sample) were added to the hyphal compartments. This experiment was carried out as a completely randomized design (CRD) with factorial arrangement in three replications. The results showed that dry shoot weight and phosphorus concentration in mycorrhizal treatments increased significantly compared with non mycorrhizal treatments. of the two fungal species, G. mosseae had more effect on phosphorus concentration in white clover plant. AM fungi increased the Zn concentration in shoot and root of white clover. AM fungi also significantly increased cadmium concentration in root of mycorrhizal treatments compared to non mycorrhizal plants. of the two fungal species, G. intraradices accumulated more cadmium in clover roots. ALL in all the results demonstrated that AM fungi increased phosphorus and Zn transferring to the shoots while cadmium transferring was decreased by stabilizing in the roots.

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The quantity and variability of soil organic carbon (SOC) is one of the most important indices to determine the effect of land use changes on the soil quality. Regarding long-term changes from rangeland to dry farming in the Roin area of North Khorasan, the objectives of this study were to investigate the effect of long-term land use changes on the SOC in different slope faces and use SOC as an index to make a proper decision about the future of land use in this area. 140 soil samples were taken from 0-15 cm soil depth of back slope position of north-, south-, west- and east-facing slopes of rangeland, dry farming, alfalfa dry farming and garden in 7 points. 14 soil samples were taken from irrigated farming, too. The results showed that garden and irrigation farming with averages of 2.03 and 0.78% have the maximum and minimum SOC content. The average of SOC content in rangeland was 1.40% that decreased by land use change to 1.04 and 1.27% in dry farming and alfalfa dry farming, respectively. SOC content in southern slope aspects showed a significant difference compared to other slope aspects. The most SOC content occurred in east aspects. It seems that after long-term land use changes, the SOC content have equilibrated to environmental and land use conditions. The average SOC content in different slope aspects except south one changed from 1.4% in rangeland to 1.11% in dry farming and 1.32% in alfalfa dry farming, which are a suitable value for semiarid regions. In conclusion, to protect land from degradation and considering this fact that dry farming is the main income of the people in the study area, it is recommended to stop dry farming on south aspects and continue on east, north and west aspects with conservation practices.

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The aim of this study was to investigate the effect of parent materials and pedogenic processes on distribution of Pb, Zn, Cu, and Ni in the residual soils derived from different parent materials in the Binaloud zone, western Mashhad. Two soil profiles on the summit of granitic, ultrabasic and metamorphic rocks were described and sampled from their genetic horizons. Pseudototal concentrations of selected heavy metals and fractions of these metals were determined using aqua-regia and sequential extraction methods, respectively. 178.1-419.7 mg kg-1of Ni in ultrabasic soil versus 0.7-27.5 mg kg-1 in the granitic soil make the Ni a distinctive element in the studied area. Cu with the average contents of 60 and 56.3 mg kg-1 in the ultrabasic and metamorphic soils respectively showed more concentration in comparison to granitic soils with 12.1 mg kg-1. The amount of Zn was not significantly different among the soils, although the average of this element in the granitic soil (55 mg kg-1) is slightly more than the other soils. Pb was only detectable in the surface layers of all pedons reaching up to 6 mg kg-1. Residual fraction except Ni and Cu in granitic soil was the main fraction for all of the studied heavy elements that was expectable according to the low weathering intensity of the soils. The eolain addition of gypsum and carbonates have influenced heavy metals concentration, especially in surface horizons. In conclusion, the amount of heavy metals was significantly affected by parent materials and the eolian deposition must be considered as the secondary influencing factor.

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In recent years, due to the increased population, urbanization and changes in human consumption patterns, urban, industrial and agricultural soils have been exposed to various pollutants such as heavy metals. The objective of this research was to identify hotspots of Pb by using global and local Moran Indices in urban and suburban soils of Kashafrood catchment. A total of 261 surface soil samples (0-15 cm deep) were taken using irregular girding network method and their total Pb concentrations were measured. The positive Moran index at confidence level of more than 99 percent showed the spatial clusters between observations. On the basis of local Moran index results, 15 samples were introduced as hotspots (high-high value) located southeast of Mashhad plain. Exclusion of extreme values resulted in the addition of high-high cluster (hotspots) leading to the extension of these areas to the West of the Mashhad city. These areas are introduced as hotspots due to the urban land use, the direction of prevailing wind, and the area being close to Mashhad airport.