APPLIED SOIL RESEARCH
Year:2018 | Volume:6 | Issue:1 |Papers Count:10

Nitrate (NO3) is an essential nutrient for growth of plants, but high concentration of nitrate in human diet increases risk of serious illnesses such as gastric cancer and infantile methemoglobinemia. Vegetables constitute the major source of nitrate, providing 80% of the average daily human dietary intake. Unbalanced fertilization and overuse of nitrogen-based fertilizers are the main reasons for excess accumulation of nitrate in vegetables. In regard with the recent concerns about contamination of vegetables to nitrate, the present study was conducted to compare nitrate accumulation in edible parts of some predominant crops in Isfahan province in comparision with critical level of nitrate in vegetables. Predominant crops grown in Isfahan including potato (Solanum tuberosum) which is basic vegetable in human diet and cucumber (Cucumis sativus) which is basic raw-used vegetable were sampled in cold season (mid-October until end-November), with high probability of nitrate accumulation, from pioneer greenhouses and farms. Nitrate concentration in edible parts of compound sampled plants were measured by diazo method. Interpolation maps of nitrate hazard quotient for children and adults based on per capita consumption of these crops were drawn. Results showed that mean nitrate concentrations in cucumber and potato samples collected from all cities were below permisible level. According to the results obtained from interpolation maps of nitrate and the fact that in all cities THQ for nitrate was below 1 (Maximum 0. 051 and O. 2 for potato and cucumber, respectively). Therefore, the health quality of the studied crops in terms of nitrate concentrations was acceptable. Although continuous monitoring of crops is essential.

Hormoz Island is a tourism resource with natural features and virgin landscapes which were exposed to damages caused by human activities. In this study, 58 surface samples were collected from the study area and total concentration of Fe, Zn, Pb, Cd and Ni were measured by using four acid digestion procedure and inductively coupled plasma instrument (ICP-OES). Cluster analysis and factor analysis were applied to identify the possible sources of the heavy metals in soils of Hormoz Island and for determination of pollution area, geoaccumulation index (Igeo) and enrichment factor (CF) were used. Fe element was identified as the most polluted element based on the values of Igeo, and CF showed the high enrichment level of this element. The obtained results from the factor analysis showed that there are a positive and strong relation between elemental group of “ Fe, Ni and Pb” and elemental group of “ Zn and Cd” . Therefore, these two elemental groups have the different origin and because of the absence of industrial pollution in the study area, this difference is probably due to different geological structure. Also, based on cluster analysis, elements of Zn and Cd were categorized in one group and Fe, Ni and Pb elements in another group. These findings confirm the results of the factor analysis and represent the same origin and the same geochemical behavior of elements in each group.

Remediation of Saline and sodic soils is usually done using leaching of excess salt and physical, chemical and biological methods and by application of mineral and organic amendments. An incubation experiment using poly ethylene columns was conducted to study the effect of using four organic and mineral amendments in a saline sodic soil (SAR=33, EC= 18. 7 dS. m-1). The treatments included: green manure, animal manure, plant residue and gypsum along with control. The water from the area (Akhtar Abad) was used to irrigate the columns. Change in some salinity and sodicity indices and the concentration of some elements in soil solution were measured and compared in soil sub-samples at 40, 80, 120, 160 days of incubation and for 0-10, 10-20 and 20-30 cm depths. The results indicated that all organic amendments especially green manure decreased soil pH compared to control (P<0. 01). Application of all amendments increased soil EC compared to control (P<0. 01). Highest EC was in green manure followed by gypsum, plant residue and animal manure, respectively. The gypsum and green manure decreased the SAR in soil compared to control (P<0. 01). The animal manure treatment did not change SAR but the plant residue treatment significantly increased SAR. In the gypsum and green manure treatments the concentration of Ca and Mg in soil solution increased significantly (P<0. 01).

Nickel (Ni) has recently added to the list of essential nutrients. Ni is needed for plants in low concentrations but it is toxic at high concentrations. Considering the importance of iron (Fe) and that Fe deficiency is one of the main nutritional problems of the Iranian people's, this study was carried out to investigate the interaction effect of Ni×Fe on concentration and uptake of Ni and Fe by corn plant (Zea mays L). A greenhouse experiment was conducted within the framework of factorial randomized complete block design (RCBD) in a calcareous soil with Ni treatments at four levels (0, 10, 50 and 100 mg Ni kg-1 soil) from NiSO4 and Fe from FeSO4 and Fe-EDDHA at five levels (0, 10 and 20 mg Fe kg-1 soil), according to two source on corn plant (single cross 704). After 90 days, plants harvested and Ni and Fe concentration of shoot and root were measured. According to the results, with increasing applied Ni levels, shoot Ni concentration significantly increased at levels 10, 50 and 100 mg Ni Kg-1 soil, respectively, 18. 78%, 41. 106%, 97. 116% compared to the control. With increasing applied Ni levels, root Ni Concentration increased respectively, 1. 27, 4. 63, 9. 18 compared to the control. With increasing levels of applied Ni in the soil, root Fe concentration significantly (P<0. 05) decreased at levels 10, 50 and 100 mg Ni Kg-1 soil, respectively, 8. 27%, 16. 1% and 32. 7%. With increasing levels of applied Ni in the soil, Fe concentration of root significantly (P<0. 05) decreased at levels 50 and 100 mg Ni Kg-1 soil, respectively, 8. 7% and 9. 3%. With the increase in Fe levels, translocation factor of nickel significantly increased 44. 8 and 48. 9 percent at 10 and 20 mg kg-1 soil when FeSO4 was Fe source and at 10 mg Fe kg-1 from Fe-EDDHA 55. 1 percent respectively. According to the results, interaction of Ni and Fe was affected by Fe fertilizer sources.

Structural and hydraulic properties of soil depend on type and quality of irrigation water. In order to investigate the effect of potassium as cation ratio of structural stability of soil on physical properties (sandy loam soil), a research was performed as completely randomizes design with factorial arrangement and 3 replications in undisturbed soil columns. Experimental factors consisted of saline water (2 salinity rate: 4, and 8 dSm-1), and different contents of potassium ion in irrigation water (4 CROSS values: 0, 15, 20, and 25). Soil columns were irrigated for 16 weeks, after then soil physical properties were measured. The results showed that when salinity increased, water dispersible clay significantly decreased, while changes of mean weight diameter of aggregates, penetration resistance and saturated hydraulic conductivity were not significant (P<0. 05). Despite sodium ion was not used in irrigation water, using of potassium ion in irrigation water had a significant effect on soil physical properties, such as water dispersible clay, mean weight diameter of aggregates (MWD), and saturated hydraulic conductivity (Ks), and they were degraded. Interaction effect of salinity and CROSS of irrigation water on soil properties in EC= 8 dSm-1 was lesser than that of EC= 4 dSm-1. Further studies are recommended to evaluate the effect of potassium on soil structure.

Pseudomonas species are usually considered as plant growth promoting bacteria which in combination with nitrogen fertilizers could exert beneficial effects on growth and nutrients uptake by plants. It seems that by using these bacteria and nitrogen fertilizer we will be able to improve growth and nutrient uptake by spinach plant as an important vegetative in human diet. To achieve this purpose, in a factorial experiment on the basis of randomized complete blocks design with three replications, spinach plant (Spinacia oleracea L. ) were inoculated with Pseudomons fluorescens or P. putida or left un-inoculated as control. Three levels of nitrogen (0, 125 and 250 mg N Kg-1) as urea were applied to the pots containing 2 kg of sterile soil. Statistical analysis showed that with increasing levels of nitrogen in soil from 0 to 250 mg kg-1, Zn uptake, leaf chlorophyll index and plant dry weight were significantly increased. By bacterial inoculation, shoot and root dry weights of spinach showed significant increase compared to the nonbacterial control and shoot and root dry weights were enhanced by 20% and 28. 1% in plants inoculated with P. fluorescens compared to the non-bacterial control. Leaf chlorophyll index was increased by 22. 2% and 13. 8% in P. putida and P. fluorescens treated plants, respectively compared to the control. Total N content in root and shoot of spinach was significantly increased in bacterial treatments especially in P. fluorescens treated plants compared to the non-bacterial control. Zn content in shoot was significantly decreased in plant inoculated with P. putida compared to the non-bacterial control. Based on the result obtained in this study, P. fluorescens caused a marked increase in growth and N uptake by development of plant root system and increasing water and nutrients uptake efficiency. Moreover, Zn uptake in spinach plant may improve through siderophore production.

Persian walnut is one of the most important nut crops. Appropriate nutrition and correct application of nutrients to the soil are of the most important factors on the growth and yield of walnuts. Nitrogen and potassium are among important elements in walnut plants’ nutrition and optimum consumption of these elements is important economically and it has a great influence on performance of walnut plant. Factorial experiment with three levels of nitrogen (0, 200 and 400 N kg ha-1 ammonium sulfate) and three levels of potassium (0, 150 and 300 K kg ha-1 potassium sulfate) in a randomized complete block design with four replications was evaluated in the Bondar Hanza village, located in Kerman province. The results showed that application of Nitrogen significantly affected concentration of nitrogen, phosphorus, calcium and Micro elements (Iron, Copper, Manganese and Zinc) in the leaves. Increasing nitrogen application, a significant increase in nitrogen, phosphorus, iron, manganese, and copper and zinc concentrations in the leaves was observed, but potassium concentration decreased from 1. 3 to 1. 08 percent and calcium concentration decreased by 0. 75 percent in the leaves. Also, application of potassium had significant influence on potassium, phosphorus, calcium and manganese in the leaves. Increasing application of potassium sulfate fertilizer, a reduction in nitrogen and calcium concentrations was observed, which shows negative interaction between these elements. Finally, it can be concluded that interaction between nitrogen and potassium on concentration of micro elements was meaningful, while it did not have significant influence on macronutrients.

Expansive soils are known as problematic soils that show volume change while subjected to moisture content variation. Changing volume of such soils, specially the basis of light structure like base of canals with rigid lining lead to cause high costs. This type of soils evolves more clay and the magnitude of expansion depends upon to the type of minerals and molecular connections. Furthermore the type of chemical materials which is added to the soil, precise an explanatory definition of engineering properties of the soil. In this research the effect of salinity on the behavior of clayey soils under wetting and drying cycle was investigated. In this regards, three expansive soil sample from Lake Urmia basin including zero, two and four weighty percent of NaCl were prepared and free swelling tests under wetting and drying cycles with monitoring of salinity variation were conducted. The results of this investigation revealed that the maximum expansive is referring to the second cycle, as well the expansive behavior after 6 cycle decrease significantly. Also, the achievements of this study confirmed that in the specimens including salt the gravity forces between ions over clays and cation increases and it cause to decrease of swelling. Whereas, in the specimens including 4% salinity the minimum expansive was shown that this may practical as a simple method to control the expansive behavior of clays.

Organic manures can effect on phosphorus sorption and its availability. Biochar as a renewable organic source of phosphorus could have a significant role in the enhancement of increase phosphorus availability in calcareous soils In this study, phosphorus sorption was performed in a calcareous soil treated with two types of of biochar prouduced from apple and grape pruning at 400 ° C at different rates (0, 10 and 20 g kg-1 soil, w/w) and three incubation periods (40, 80, 120 days). Phosphorus adsorption data were fitted to Langmuir, Freundlich and Temkin models. According to the observations the use of biochar reduced phosphorus adsorption in the soil while increased the release of phosphorus. Based on the coefficient of determination (R2) and the standard error of estimation (SE), all three models Langmuir, Freundlich and Temkin fitted well with the experimental data. High values of Langmuir (qmax) was observed (785 mg. kg-1) in untreated soil and low values were observed (415 mg. kg-1) at the 2g. kg-1 levels of grape biochar. Moreover the binding energy (Kl) declined from 0. 3 to 0. 04 (l mg-1). Capacity parameters (KF) of freundlich was variable from 14-90. 5 in the apple and grape biochar treated soil and was 95 in the untreated soils. The intensity adsorption (n) parameter of freundlich was variable from (0. 1-1. 5 ) in the apple and grape biochar treated soil and 1. 25 in the untreated soil. The parameter of (kt) of temkin declined from 93 to 40 g. kg-1. Phosphorus adsorption parameters, qmax and Kl of Langmuir, n and Kf of Freundlich and Kt of Temkin declined in all treatments with the in incubation periods. The value of soil buffering indices including buffering capacity maximum (MBC), phosphorus buffering capacity (PBC), standard buffering capacity (SBC), equilibrium buffering capacity (EBC), and phosphorus standard requirement (SPR) declined in the apple and grape biochar treated soil as Compared to the untreated soil. It can be generally concluded that use of apple and grape biochar reduces the phosphorus adsorption zones in calcareous soils while increases the solution phosphoruse.

The aim of this study was to evaluate the physico-chemical properties and clay mineralogy in paddy soils of Doroud region in Lorestan province. Seven profiles were sampled and described and all soil profiles were classified in Inceptisols and Entisols orders. According to the results, clay content of soils due to waterlogging was high. Due to the reduction Conditions, pH of all soil samples was nearly neutral. Due to the flooding and accumulation of oxides of bivalent iron and manganese in the upper horizons of soils, the electrical conductivity (EC) was higher compared to the lower horizons. With increasing depth and getting closer to native materials, lime percentage was increased too. In most profiles due to the higher percentage of organic matter in the surface horizons, cation exchange capacity in the surface horizons was more than the lower horizons. The amount of organic matter was high in the surface horizons because of the less oxidation of plant residues in anaerobic conditions. The most clay minerals were chlorite, smectite, vermiculite, and illite respectively. Palygorskite, kaolinite and mixed minerals had very low content. Chlorite, illite, kaolinite and palygorskite often were inherited. The source of smectite can be also transformation of illite or palygorskite, under waterlogging condition. The puddling condition increased the amount of chlorite in paddy soils. The results showed that the type of clay minerals didn't vary in paddy soils and their relative percentage varied. The waterlogging provid conditions for sustainable of vermiculite in paddy soils. The long term waterlogging condition affected soil quality in this area, and however cultivation rotation suggested.