Iranian Journal of Soil Research
Year:2008 | Volume:22 | Issue:1|Papers Count:20

There is little, if any information available regarding Cu availability in calcareous soils of Iran. The availability of this nutrient is generally low in such soils and further reduced by waterlogging. Therefore, it is very important to assess study effect of applied Cu to rice plant. In this study, Nineteen surface soil samples (0-30 cm) were collected from different fields in Fars Province with a wide range of physical and chemical properties. DTPA-TEA used to extract available Cu. Furthermore, the effects of two levels of Cu (0, 2.5 mg kg-1 as CuSO4. 5 H2O) on the growth and Cu concentration and uptake in vegetative and reproductive stages were studied in a completely randomized design with 3 replications. Thousand grain weight, harvest index, biological yield and chemical composition of plant were also determined. Mean top dry weight, grain and straw yield, Cu concentration and uptake, thousand grain weight, harvest index and biological yield were significantly higher in Cu-treated soils than those in untreated soils. Application of Cu decreased concentration of Fe, Mn and Zinc by plant. Furthermore, The critical level of Cu in these soils with DTPA was calculated 1 mg/g with Cate-Nelson method and for obtaining 80%, 85% and 90% relative yields with Mitscherlich-Bray method, critical levels of Cu in soils were obtained 1.40, 1.65 and 2 g/g, respectively. Whereas, critical level of Cu in grain was determained 5.93 mg/g.

A significant portion of zinc( Zn) chemical fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore, affect the growth and chemical composition of the subsequent crops. This is called the residual effect of Zn. Soil tests may be used to predict such effects. The present experiment was conducted to study the residual effects of zinc sulfate on the subsequent crop of soybean (Glycine max L.). Twenty soils of northern Iran (5-39% calcium carbonate equivalent), previously treated with two levels of Zn (0 and 20 mg Zn kg-1 as ZnSO4) and under one crop of soybean, was used in greenhouse to grow a subsequent crop of soybean without additional Zn fertilizer but with uniform application of nitrogen, phosphorous and potassium. Soils were sampled before the subsequent crop and extracted with Zn extractant DTPA. Dry weight of plant tops and Zn concentration and uptake after eight weeks under the greenhouse conditons were used as the plant responses to residual Zn in soil. Statistical analyses showed that zinc sulphate application significantly increased the dry matter from 16.56 to 20.17 g/pot. Zinc application also increased leaves Zn content and Zn uptake from 53.5 to 90.9 mg/kg and from 0.863 to 1.884 mg/ pot., respectively. The overall effect of previosly- applied Zn on dry matter were nonsignificant, but seed yield, Zn concentration and uptake were significantly increased. In all soil, grain yield increased 10.8% in comparison with the control. The residual effect of Zn on dry matter and seed yield of the third crop in soils were nonsignificant, but Zn concentration increased 21.7% in comparison with the control.. In the fourth crop, residual effect of Zn increased dry matter yield and Zn concentration 3% and 40.2% in comparison with the control, respectively. It was concluded that with attention to similar research results, application of ZnSO4 can obtain plant need for 4 years in soybean farms.In this context, farther research conduction is suggested.

This study was conducted to determine the importance of organic acid type and concentration in the rhizosphere of wheat plant (Triticum aestivum L.) and its effects on 33P uptake by roots. Organic acids such as citrate and oxalate are implicated in rhizosphere processes, including nutrient acquisition. A single wheat plant was grown in soil-filled rhizosphere microcosms and allowed to pass through a KH233PO4 labeled of soil. Forty-eight hours after 33P injection, citrate and oxalate at concentrations of 1 and 10 mM were injected into the microcosms at the same location every day over a period of 4 days. Oxalate resulted in about 2-fold enhancement in plant 33P accumulation, but citrate had no such effect. High mineralization of citrate was observed in comparison with oxalate. It seems that due to more mineralization of citrate, 33P uptake was prevented. As a result, organic acids cause an increase in P mobilization and P uptake by plant is enhanced.

Sewage sludge is widely used as a fertilizer and soil conditioner on agricultural lands. However because of high concentration of heavy metals in sewage sludge, it increases soil heavy metals concentration. The objective of this study was to evaluate the residual and cumulative effect of sludge application on heavy metals availability. This study was conducted in Lavark experimental site with four rates (0, 25, 50 and 100 ton/ha) of sewage sludge. The plots received one, two, three or four years of sludge applications. Corn (Zea mays) and wheat (Triticum sativum) were planted in the first and second half of each year, respectively. Soil samples were collected at the end of wheat growing season at 20 cm increments to 100 cm depth from each plot. Soil samples were analyzed for pH and electrical conductivity (EC) using a saturated paste, organic carbon, calcium carbonate and exchange capacity (CEC), extractable Cd, Pb, Cu, and Zn, and soil particle-size distribution, Chloride and bicarbonate concentrations were measured. Sewage sludge application result in heavy metals leaching and movement down ward in the soil profile. There was a high correlation between the Cd and Zn availability and amount of organic carbon and Cl- concentration and also between the Pb and Cu availability and amount of organic carbon in soil. It seems that the formation of Cd and Zn complexes with Cl- and O.M and the formation of organic complex with Pb and Cu is the most important factors to increase the solubility and movement of these metals.

In the process of conversion of solid waste refuses to compost, leachate is produced. Although municipal waste compost leachate is one of the problems of compost production in Iran, it may be considered as a source of water and nutrient. Municipal waste compost leachate contains micronutrients (Fe, Zn, Mn and Cu) that can be used by plants. Furthermore, microorganisms have important effects on nutrient cycle in soils. Therefore, a greenhouse experiment was conducted to study the effect of municipal waste compost leachate on micronutrients uptake by plant in sterile and non-sterile conditions, with three watering treatments (distilled water, non-sterile leachate and sterile leachate), three different treatments on soils (non-sterile soil, sterile soil + re-inoculation with non-sterile soil and sterile soil) and tow plants (lettuce, Lactuca sativa and maize, Zea mays) in a factorial complete randomized design with three replication. Results of this study showed that, plant uptake of Zn increased significantly under the leachate treatments. However, plant uptake of Fe, Mn and Cu were not affected by leachate treatments. In most cases, there was not significant difference between sterile and non-sterile leachate for micronutrients uptake by plant. Leachate application also increased DTPA extractable Fe but, DTPA extractable Zn Mn and Cu didn’t show any significant increase under the leachate treatments. Although Zn uptake by plant increased under the leachate treatments, DTPA. In general, use of leachate in soil for lettuce and maize had positive effect on plant yield. Concentration of Fe, Zn, Mn and Cu in plants studied did not exceed standard permissible levels of the metals with the application of leachate as liquid organic fertilizer.

Soil erodibility defines the resistance of the soil to both detachment and transport. This factor may be affected by some soil physicochemical properties. This study was conducted to determine physicochemical properties affecting the erodibility (K factor) in calcareous soils. The study was conducted in the Hashtrood, located in northwestern Iran, from March 2005 to March 2006. The study soils had almost 13% lime and 1% organic matter. In order to investigate, the square network of agricultural soils with 900 km2 in area was selected and divided into 36 regular grids. In each grid, the erosion plots designed agreement to unit plot at 3 replicates with 1.2 m spacing. The physicochemical soil properties consited of sand, coarse sand, very fine sand, silt, clay, gravel, organic matter, lime (TNV), potassium, aggregate stability and permeability were measured in the study soils. The soil erodibility was measured based on annual soil loss amount per unit rainfall erosivity factor. The soil loss at the unit plots was affected by 23 natural rainfall events during the study period. Avereage soil loss and soil erodibility in the study area were 1.868932 t/ha.year and 0.004258 t.h/MJ.mm respectively. The soil erodibility significantly was affected by sand, silt, organic matter, lime, aggregate stability and permeability. Silt contrary to sand, organic matter, lime aggregate stability and permeability increased the soil erodibility. Correlation between the soil erodibility and clay, gravel and potassium was not significant. Study of effect of the physicochemical properties on the erodibility with principal component analysis method revealed that the soil erodibility mainly is affected by permeability, clay and lime. These soil properties significantly (R2=0.84, p<0.001) decresed the soil erodibility.

The proper use of saline soils to produce maximum yield of crop plants has always been a big challenge in the agricultural sector. Plants, cropped in saline soils, are affected by salinity through different ways and hence, they may not reach their maximum yield. Ethylene accumulation in the roots is one of these ways, being harmful to the plants such as canola (Brassica napus). Ethylene accumulation reduces root growth and hence crop yield. If there are ACC deaminase producing bacteria in the rhizosphere, it may be likely that these bacteria change ACC precursor to a-ketobutyrate and ammonium, resulting in the decreased ethylene level in the host plant. Hence, with respect to the importance of developing canola cropping area in Iran and the necessity to plant it in saline and relatively soils, it seemed necessary that in the first step, some bacteria, with the mentioned ability, be isolated and identified. For this reason 21 combined soil samples along with the canola roots were collected from the saline and relatively saline soils of Qom and Qazvin provinces. After determining some chemical and biological properties of the soil samples, 105 strains were selected from the soil rhizosphere of canola. According to the growing abilities of the strains in the minimum media of DF having ACC, as the only source of nitrogen, it was determined that 15 strains had the ability to produce ACC deaminase. Identifying these strains, according to the microscopy, physiological and biochemical characters, mentioned in the Bergey book, entitled, Systematic Bacteriology, showed that all the strains belonged to the group of fluorescent Pseudomonads. According to the tests, related to strain determination, 14 strains were identified as P. fluorescens. Due to the lack of accordance with the characters in the Bergey book one of the strains was identified as Pseudomonas sp. Also measuring ACC deaminase activity showed that the activity of this enzyme in the isolated strains differed from 1.43 to 8.17 mmol a-ketobutyrate/mg/hr. According to our results and in comparison with the results of other researchers, it may be beneficiary to inoculate canola seed with the identified strains to alleviate the stressful effects of salinity on canola growth and, hence yield.

More than 4 million hectars of arable land of the country is devoted to saline and alkaline soils. Ion toxicity and reduction of availability of water and nutrient elements in crop plants decrease grain yield and yield component. Major parts of the arable saline lands are devoted to strategic crop plants such as wheat and barely. Reports indicate that application of chemical fertilizer for increasing grain yield is not economically beneficial to farmers. Therefore, new approaches are needed to increase grain yield in this type of soils. One of the approaches in increasing grain yield is to provide a symbiosis relationship between various species of Vesicular Arbuscular Mycorrhiza Fungi and different wheat cultivars. The objective of this study was to clarify the role of mycorrhizal symbiosis on increasing grain yield and yield component of wheat cultivars grown under saline stress in controlled condition. A Completely Randomized experimental design was set up in three level of salinity treatments (4, 8, 12 dS/m) from both NaCl and CaCl2 sources, 5 levels of inoculations with arbuscular mycorrhizal fungal species [Glomus mosseae, G. intraradices, G. etunicatun, mixture of three mentioned species and a control (non inoculated)] on two salt tolerant and semi-tolerant wheat cultivars (promising line 9 [Bank “S”/vee “S”] and Chamran) in four replication under greenhouse condition at Karaj in 2006. Results showed that new salt tolerant wheat line 9 had higher grain yield compared with semi-tolerent Chamran wheat cultivar. Yield component such as kernel weight, kernel number per spike, kernel weight of spike and morphological characters such as spike length, dry weight of shoot and root were increased in Line 9 compared to chamran cultivar. Inoculation by mycorrhizal fungi species in both wheat cultivars, particulary under high levels of salinity stress, increased grain yield significantly (P£0.05). Compared to control treatment with no inoculation the highest grain yield and yield component obtained from the fungal mixture inoculation treatment.

In this study, isolated strains of nitrogen fixing bacteria and pectynolytic bacteria which can able to create paranodule on wheat seedling were selected from soils. Then the best nitrogen fixing bacteria and high capable peptonize enzyme production bacteria were chosen. 2.4-D was used as Abiological agent (Aa) and the best pectolitic bacteria as Biological agent (Ba) (Bacillus polymyxa Strain 43) for study formation Para - nodule on wheat seeding and also used diazotroph bacteria for inoculation Wheat Seeding. Nitrogen-fixation Activity on wheat roots was measured in dynamics on the 8th, 10th, 14th and 22nd days of plant growth. The experiment was carried out in 9 variants as following. 1) Wheat without any treatment (control) 2) Wheat + Aa 3) Wheat + Ba 4) Wheat inoculated + mixed cultures of diazotrophic bacteria (Arthrobacter sp + Xanthomonas sp). 5) Wheat + Bacillus polymyxa Strain 42 6) Treatment 4 +Aa 7) Treatment 5 + Aa 8) Treatment 4 + Ba 9) Treatment 5 + Ba. The formation of P- nodules on wheat roots was observed in the 4-5th day of plant growth. Their diameters were about 0.5-1 mm. It was shown that the significant differences in the number of P- nodules and also the rate of nitrogen fixing activity on wheat roots depending on the treatments. The maximum nitrogen-fixing level was recorded after wheat plant inoculation with mixed culture (Arthrobacter sp + Xanthomona sp) on the 14th day of plant growth.

The reduced yield and poor quality of ornamental flowers produced in Iran have been threatening ability to compete in international market. Some of the important and effective factors that determine the yield and quality of ornamental flowers include, the calcareous nature of soils, negligence in providing proper and balanced nutrition, and the poor quality of irrigation water used to grow ornamental flowers. High pH as result of high concentrations of bicarbonate in irrigation water are leading to the reduced water quality. Obviously use of poor quality water in the commerical glasshouses increases the pH of plant sap and lowers the activity of such elements as phosphorus, iron, zinc and manganese within the conductive tissues. In order to evaluate the effect of eliminating irrigation water bicarbonate on the yield and quality of carnations produced by Khadem nurseries located at kilometer 30 of Khavaran Highway in Golzar village, an experiment was carried out during 1999-2000 growing season in the following manner. After measurements and calculating the amount of sulfuric acid required to lower the pH of irrigation water to 6 by titration, two treatments were tested, namely: T1=applying Kristalone green fertilizer + irrigation with well water, and T2=applying Kristalone green fertilizer + acidified water (pH=6) for irrigation. Based on measurements 46 ml of 36 N sulfuric acid was required to lower pH of one cubic meter of irrigation water to the desired level (6). A randomized complete block design with 3 replications was used in this experiment during which the yield and quality characteristics of the carnations were evaluated. Results showed that applying acidified irrigation water (pH 6) significantly (a=0.05) increased the diameter of flower disc as well as the chloropyll content of the leaves. The acidified water (pH=6) also significantly improved (a=0.01) the height and the diameter of flowering stems and the vase life of flowers as compared to the control. Furthermore, T2 (Acidified water) Significantly (a=0.05) decreased stem lodging (bending), disc splitting as well as the leaf concentrations of Zn and B but increased the concentration of phosphorus at 1 % level of significance.

The purpose of this research was to investigate and compare the performance of a synthetic drainage envelope material with a granular envelope material vastly used in drainage projects of the region. This study was conducted in the soil and water research laboratory of Chamran University. Upward flow cylinder infiltrometers was used in these experiments. Granular envelope was designed according to USBR recommenedations, and synthetic the envelope used was PP450. Drain outlet discharge variation, soil-envelope hydraulic conductivity under fixed hydraulic head and gradient ratio (GR) in the two envelopes were measured and compared. The results of GR test indicated that clogging potential was greater in the synthetic envelope. In regard to hydraulic conductivity, the performance of both envelopes was acceptable and could be used as drainage envelope material satisfactorily. Under all hydrylic heads used in these experiments, drain outlet discharge for the granular envelope was higher than synthetic envelope material.

Considering the fact that drought is frequently one of the limiting factors in crop production in dry regions, suitable solutions in overcoming drought is of major importance. For this purpose, an evaluation was made of the effect of potassium sulfate on improving the drought resistance of Chamran wheat variety (Triticum aestivum L.). The experiment was carried out in a completely randomized split plot design in three replications for three growing seasons (1999-02) at Darab Agr. Res. Center. The main factor consisted of four levels of irrigation extracted from the book on water requirement: 1. (the control); 2. Twenty percent less water than used for the control (as a moderate drought stress); 3. Frothy percent less water than used for the control (as medium level drought stress); and 4. Sixty percent less water than used for the control (as a severe drought stress), and the subfactor consisted of three levels of potassium, namely, 0, 100 and 200 kg K2O/ha as potassium sulfate. The three year research showed that the yield decreased under drought conditions. While the yield for the control treatment was measured at 5821 kg/ha, it was reduced to 5404, 3927 and 1967 kg/ha for moderate, medium and severe drought conditions, respectively. However, the rate of yield losses was reduced as a result of the application of potassium sulfate. In other words, with the application of potassium sulfate, yield losses were moderated even under severe drought conditions. The results also showed that the losses in grain yield were negligible as compared with the control even with a 20% reduction in water consumption. However, by decreasing the water consumption levels by 40% and 60%, instead of 20% severe drops in grain yields were observed. The application of 100 and 200 kg K2O/ha of potassium sulfate significantly lowered the grain yields by 9.5 and 16.3%, respectively, as compared with the control. The increases in grain yield seen with potassium applications were caused by the increases in the yield components. It was concluded as a whole that with the application of 200 kg K2O/ha, the level of drought resistance as well as the grain yield improved under drought conditions; the negative effects of moisture deficiency on the losses of grain yields were also moderated to some extent. Therefore, potassium application under various levels of drought stress can offer a practical solution for improving drought resistance as well as preventing yield losses in wheat.

Drought is an important environmental factor which reduces wheat production in arid and semi arid regions. The response of wheat to three levels of water stress at three growth stages, namely, heading, flowering and grain filling was studied under field conditions at Kahriz Station of Uromieh for two years. The experimental design was factorial (complete block) in three replications. Experimental treatments were time and amount of irrigation and included: t1=irrigation at heading, flowering and grain filling stages. t2= irrigation at flowering and grain filling stages. t3= irrigation only at grain filling stage. Treatments of water amount were: W1, W2, W3, respectively, 40, 70, and 100% of evaporation from class A pan. The MSTATC software was used for statistical analyses of grain yield water use efficiency, 1000grain weight, and protein percentage. The main effect of irrigation timing and amount and their interaction showed significant differences for grain yield, water use efficiency, 1000 grain weight and protein percentage. The comparison of means was done by Duncan, s method. The highest significant grain yield, 5.59 t/ha, was obtained with t1 W2 (irrigation at 3 growth stages with water application 70% of class A pan). At all stages of growth, moderate and severe water stress decreased plant height, 1000 grain weight, grain yield and water use efficiency. Wheat was most sensitive to water stress during the flowering stage. Results suggest that in Kahriz area and similar other locations, when water is scarce or limited, wheat crop should be irrigated at heading and flowering stages with an amount equal to 70% of evaporation from class A pan.