Iranian Journal of Soil Research
Year:2006 | Volume:20 | Issue:2|Papers Count:18

It is well known that Ni is an essential nutrient for the higher plant as it controls the N metabolism. An experiment was conducted to asses the effect of different levels of Ni (0, 0.5, 1 mg L-1) supplied with either urea or NH4NO3 on cucumber (Cucumis sativus) growth, yield and quality of two cultivars namely Sina and Vikima. The experiment was arranged in completely randornized block with four replications. Nickel as NiS04 was added to the Hoagland's, solution. The concentration of N was set to 200 mg L-1 by adding either NH4NO3 or urea. During the experiment period, fruits were harvested twice per week and the total yield was recorded for 4 months. Fruit quality such as TSS, fruit color, EC and pH in the juice were measured. At the end of the experiment, two plants from each plot were removed for detraining leaf number and leaf area. Photosynthesis (pn) was measured at the young leaves of the plants. The results showed that the treatments had significant effect on yield in Vikima cultivar. At 0.5 mg I-1 Ni concentration, the highest yield, 1.45 and 1.53 kg per plant was obtained in urea and NH4N03-fed plant in Vikima cultivar, respectively. No significant effect of Ni treatments was observed on the yield of Sina cultivar. The dry weight of urea-fed plant at 0.5 mg I-1 Ni concentration was 16.5% higher than that of 0 mg L-1. However in this cultivar, dry weight of fruits reduced in NH4NO3-fed plant as the result of the increased Ni concentration in the solution. The concentration of Ni in the leaves was increased as the Ni level increased in the nutrient solution. The concentration of Ni varied between cultivars so that Sin cultivar had lower Ni concentration than that of Vikima cultivar. Use of Ni up to 0.5 mg L-1 significantly increased the fruit color in Urea-fed plants, but it reduced when the concentration of Ni in the solution raised to 1 mg L-1. The EC of fruit juice was also affected by the treatments. It can be concluded that adding 0.5 mg L-1 Ni to the nutrient solution improves cucumber growth in certain cultivars where the plants supplied with urea, but in the others increased Ni in the solution even at 0.5 mg L-1 concentration lead to reduction plant growth and yield. In general, higher concentration (1 mg L-1) of Ni appeared to have the opposing effect on the cucumber growth.

A five-years research project lasting from 1998 through 2002 was conducted in order to evaluate the process of optimizing fertilizer recommendations on wheat using comprehensive computer models. The potential yields for any region of the country was taken to be equal to the maximum yield figures obtained with actual research data gathered from field work as well as data obtained with maximum potential yield estimations. Based on our calculations, the most important soil and water production factors can be listed as the rate of water application, the salinity level of irrigation water, calcium carbonate equivalent (TNV), soil texture, and finally the level of soil salinity which can determine the expected crop yield. Measuring the effect of any of these variables on crop yields enables us to calculate the potential yield for that soil. It is, therefore, necessary to evaluate the potential yield for any field before we can make any fertilizer recommendations. The rate of nutrient requirement for any crop on any field location would be calculated after determining the concentrations of plant available nutrients by using tables on different soil nutrients in addition to estimating the potential yield. The computer model input data include soil analysis data, water analysis measurements, the name of province, town and then with pressing OK tab, output datas include fertilizer recommendations for macronutrients, micronutrients and organic materials, data on crop variety, data of planting and the rate of seeding which should appear on the monitor and be automatically stored in the information bank memory and could be viewed on the monitor and printed as needed. This computer program was written in Visual Basic with the objective of using research data in a single model so as to be able to find quantitative answers in a simple fashion. Of major importance is the fact that the program is mechanized as to include the use of suitable date of planting, rate of seeding, and soil amendments in addition to including soil parameters, organic contents, and plant varieties for every region on irrigated production.

This experiment was conducted in order to determine the effects of potassium and micronutrients on the yield and fruit quality of 8-year old orange trees cv. "Marrs" during 2001-2003, at Safi Abad agricultural research center (north Khuzestan) in Dezful, Iran. During first year, nine treatments were arranged in a randomized block design with three replications (each plot including one tree). Treatments were: T1: control, 1000 gr/tree ammonium sulfate as broadcasting application; T2: 1000 gr/tree ammonium sulfate as broadcasting application + 50 kg/tree organic matter and 250 gr/tree sulfur powder as localized placement; T3: T2 + 415 gr/tree potassium chloride; T4: T2 + 500 gr/tree potassium sulfate; T5: T2 + 830 gr/tree potassium chloride; T6: T2+ 1000 gr/tree potassium sulfate; T7: T3 + micronutrients consisting of zinc sulfate (120 gr/tree), iron sulfate (200 gr/tree) and manganese sulfate(200 gr/tree); Tg: T4 + micronutrients (like T7); T9: T2 + 250 gr/tree potassium sulfate before start of the growth season + 207.5 gr/tree potassium chloride in the middle of growth season + micronutrients (like T7). Druing the second year, based on results of first year, nitrogen fertilizers were applied in all treatments. Also foliar application of Zn-EDTA (0.3%) was tried in T7, T8 and T9 treatments. The results of combined variance analysis revealed that yield of T7 and Tg treatments with 37.7 and 34.7 kg/tree increased significantly at 5% level as compared to control (25.2 kg/tree). Other treatments did not show any significant difference with control (T1). During the second year, foliar application of Zn-EDTA increased leaf zinc concentration significantly in T7, Tg and T9 in comparison with other treatments, but did not affect the yield or fruit quality indices. Other leaf mineral concentrations and fruit quality indices were not affected by the treatments.

Investigation of over 5000 soil samples of wheat fields in Khuzestan province showed that the amount of organic carbon (OC) is less than 1% in more than 80% of the fields. Application of organic manures is important to increasing of soil organic matters and wheat production. Therefore, a trail has been carried out for five years consecutively by split plot experiment design with two factors in permanent plots in the Shavoor Agriculture Research Station on the north of Ahwaz city. Main factors were kinds of manure, including: cattle and hen manures, filtercack and baggass of sugarcane and wheat straw which compared with a control (without any organic manures) and subplots were amounts of manure, including: 2.5, 5 and 10 t/ha. At first, manures were scattered on soil surface of each plot and then, mixed with topsoil by disc. The results showed that the best treatments to increase wheat yield and its components are filtercack, cattle and baggass of sugarcane, respectively. Also, the most suitable amount of manureis 2.5 t/ha, because there was no significant different between treatments. It is recommended that some organic manure apply together, for example, filtercack with baggass and cattle or hen manure with wheat straw.

Phosphorus (P) is an essential nutrient in crop production. On the other hand its effect on micronutrients deficiencies and environmental quality has raised more concern about it. Since moisture level and soil properties are among the most important factors affecting P reaction in soils. the present study was carried out to evaluate the effects of Prates ( 0 and 300 mg P Kg-1 soil, as KH2PO4), and two moisture levels (waterlogging and 20% w/w water content) on native Olsen-P and recovery of added P in 20 calcareous soils with different physico-chemical properties at 1,2,5, 10,20,40,80 and 160 d incubation in a completely randomized design in duplicate. Path analysis was used to evaluate direct and indirect effects of soil properties on P recovery. Results showed that water logging significantly increased native Olsen-P in 1, 2,5 and 10 d, compared to that of 20% w/w, but had no significant effect in other incubation times. Water logging significantly decreased the recovery of added P in 80 and 160 d compared to that of 20%w/w, but did not affect other incubation times. Analysis of variance showed that moisture level and the interaction of moisture level and soil properties was significant on P recovery in 80 and 160 d. thus the effect of soil properties on P recovery was evaluated for these time periods. Under water logging conditions Fe, AI, and Mn compounds, clay and the ratio of clay/ACCE (active carbonate calcium equivalent) negatively; and CCE positively affected the recovery of applied P. A similar trend was observed for 20% w/w, however the effect of Fe compound and CCE was not significant. Path analysis showed that the direct effect of CCE and ACCE on P recovery was higher in 20%w/w than water logging. Path analysis also revealed the importance of direct and indirect effect of CCE and clay/ACCE in both moisture levels on P reaction in our highly calcareous soils. Since P reaction is considerably affected by Fe, Al and Mn compounds, it is suggested that to evaluate the effect of chemical transformation of AI, Fe, and Mn on adsorption and desorption of P under different moisture regimes.

Determination of forms of soil phosphorus (P) is important in the evaluation of soil P status. Amount and distributions of soil organic and inorganic P - fractions were examind in 53 soil samples of Hamedan province. Soils were sequentially extracted to determine organic and inorganic P fractions. Inorganic P was divided in to 6 fractions: Dicalcium phosphate (Ca2-P), Octacalcium phosphate (Ca8-P), Apatit (Ca10-P),P absorbed by Al oxides (AI-P), P absorbed by Fe oxides (Fe-P) and Occluded P ( O-P). The results showed that wide range in content of P fraction. The amount of total P (TP) ranged from 926 to 2686 mg kg-1 with an average of 1533 mg kg-1 soil. Calcium phosphate (Ca2-P+ Ca8-P + Ca10-P) ranged from 104 to 1872 mg kg-1 with an average of 801 mg kg-1 soil and being comprised of 78.5 and 52.3% inorganic and total P respectively. The amount of Fe-P ranged from 1 to 185 mg kg-1 with an average of 59 mg kg-1 soil and being comprised of 5.8 and 3.8% inorganic and total P respectively. The amount of AI-P ranged from 4.6 to 523 mg kg-1 with an average of 128 mg kg-1 soil and being comprised of 12.5 and 8.3% inorganic and total P respectively. The amount of O-P ranged from 0.0 to 371 mg kg-1 with an average of 33 mg kg-1 soil and being comprised of 3.2 and 2.2% inorganic and total P respectively. The amount of organic P ranged from 75 to 676 mg kg-1 with an average of 277 mg kg-1 soil and being comprised of 18.1% total P. The results of correlation study showed that available P (P extracted by Olsen method) was significantly correlated with Ca2-P, Ca8-P, AI-P, Calcium phosphate (Ca2-P + Ca8-P+ Ca10-P) and (Aluminum, Iron oxide: AI-Fe-P), This result indicate that these fractions probably can be used by plant.

Application of sulfur is one way to increase the availability of insoluble nutrients in calcareous and alkaline soils. Effectiveness of elemental sulfur depends on the activity of sulfur oxidizing bacteria especially, Thiobacillus genus. To evaluate the possibility of partially substituting sulfur along with Thiobacillus inoculum for phosphorus and micronutrient fertilizers, a randomized complete block factorial experiment was carried out on corn for two consecutive years. The treatments included four levels of sulfur (200, 400, 600 and 1000 kg/ha), four levels of Thiobacillus inoculum (at rates of 0, 1, 2 and 4 percent of sulfur) a control and balanced fertilization based on soil tests, during the first year. Following soil preparation and establishment of 72 plots measuring 5 * 2.4 m, each fertilizer was applied according to the treatment schedule, and finally a Single Cross 704 variety of corn was planted every 17.5 cm on rows 60 cm apart. Leaf samples were collected when the plants tasseled. At the end of the growing season the plants were harvested on two middle rows in 4.2 m2 sections, then the fresh weight, the dry weight, average length and weight of ears, as well as the concentrations of iron, zinc, copper, manganese and phosphorus were determined in the stems, leaves and grains. The treatments for the second year of the experiment included three levels of sulfur (200, 400 and 600 kg/ha), two levels of Thiobacillus inoculum (at the rates of 0 and 1% of sulfur w/w), a control, and balanced fertilization based on soil tests. Following fertilizer treatments on 24 plots prepared as the year before, corn was planted in the same way. Other cultivation practices, harvesting, irrigation, fertilizer application sampling and analysis, measurement of various other parameters, as well as statistical procedures were performed as in the first year. Data from the first year showed that there were no significant treatment effects with respect to weight and length of ears or the absorption of phosphorus, iron, zinc, copper and manganese in the shoots, even though the concentrations of phosphorus, iron, copper, zinc, and manganese in the shoots were significantly different for the different treatments. However none of the treatments were significantly different from the control or triple super phosphate with respect to the concentrations effects for the nutrients listed. This was true even though the treatments significantly affected the shoot dry weights. The dry weights for the control plot, optimal fertilization and treatment T4 (with the highest yield) were 30.62, 35.83 and 37.71 tons per hectare, respectively. Where the last two treatments were statistically the same but significantly different from the control. Treatments T2, T4, T5, T7, Ts, T10,T13, T14 and T15 were statistically the same as triple super phosphate treatment, while the rest of the treatments had the same statistical significance as the control. Data from the second year showed that there were no significant treatment effects with respect to dry weight and nutrients uptake in the shoots, even though the concentrations of phosphorus, iron, copper, zinc, and manganese in the shoots and seed were significantly different for the different treatments, and treatment Ts (optimal fertilization) was the best.

In this investigation 3 strains of Agrobactrium rhizogenes (A4S, A4V and a strain assigned to this species) were used to inoculate 7 types of plant tissues including carrot disks, leaflets and cotyledons of bean, the stem of bean seedling, internodal section of tissue- culture propagated potato stems, radicle of alfalfa and internodal areas of the stems of alfalfa plant. In carrot disks, leaflets and stem of bean and potato clusters of hairy roots were observed at the site of inoculation. Calculation of the percentage of appearace of hairy roots in different plants by different strains of A.rhizogenes indicated an interaction between strains of the bactrium and the species of the plants used.

The obligate Arbuscular mycorrhizal fungi that live symbiotically on plant roots can be found on some 80% of plant families. Despite their useful effects, the problems with growing them in synthesized culture media caused by their obligate symbiotic nature poses as the major obstacle in utilizing them for agricultural purposes. So far three methods of industrial scale reproduction of the fungi, namely, the methods of hydroponic, aeroponic, and simultaneous in vitor culturing of roots and fungi have been successfully developed. Of the three methods, the last one is the most effective both in term of inoculant purity as well as economic returns. This investigation was carried out on the basis of the need to develop and expand the method of simultaneous in vitro culturing of the fungi and roots of host plant to be used as pure inoculant as such. For this purpose, the spores of the fungi Glomus intraradices indigenous to the soils of Iran were used in the experiment. Young spores removed from the host plants medium of growth were washed several times with distilled water and Tween 20 solution in order to eliminate any surface contaminations. The spores were then surface sterilized first with a 2 percent solution of chloramin-T and then with a solution contining 200 mg/liter of streptomycin sulfate and 100 mg/liter of gentamycin sulfate. In order to check for any possible contamination, the spores were transferred to a minimum culture medium and maintained for one week at 25°C. Symbiotic relation was obtained by placing decontaminated spores on the end of induced root hairs found on the surface of the minimum culture medium. A simultaneous reproduction of the fungi and the root hairs was achieved using screw cap glass bottles containing 100 ml of the minimum culture medium. By staining the resulting spores with a solution of MTT, it was seen that 95% of the spores were active and capable of growing. Likewise, it was found that 70% of root colonization by the spores was successful. The investigations show that the in vitro method of reproduction used in this experiment is very effective for growing Glomus intraradices and possibly other species of Arbuscular mycorrhizal fungi.

Effect of long period and seasonal heat regimes on field soils were studied by the researchers who work on thermal soil physic. Although, they were presented some suitable models, they are not applicable for short-time heat transfer evaluation in the shallow field soils. In this paper transient heat transfer during residual burning and flaming on field soils were analyzed by using the semi-infinite solid method. Field soil was assumed as a semi infinite object by considering the ground surface as a boundary condition and depth of soil as an infinite direction. Thermal diffusion in soil layers due to residual burning and flaming was analyzed mathematically by simplification based on the physical condition and the results of other researchers. The complex derived mathematical equations were simplified by statistical models. These models were function of soil moisture content and texture. Finally the resulted models were verified theoretically by empirical experiments of other studies. The presented model that was called SDE (Soil Diffusivity Estimator) showed that flame remaining time period and soil conditions (moisture content and texture) are more important than surface flaming heat intensity. Minimum heat transfer occurred at dry and low sandy soil, and maximum heat transfer was at dry but high sandy soil. Therefore, the resulted model of this study can be used to find the best soil moisture content, depends of soil texture, during residual burning for minimum heat diffusivity in the soil. Another result showed that in conventional condition, the effect of heat flaming was not diffused lower than 0.5 cm depth of the soil. But during residual burning, although the fire temperature was low, the effect of surface temperature was up to 2.5 cm soil depth. At the worse condition, during residual burning, the maximum depth thermal diffusivity was lower than 5 cm, which soil micro organisms were affected by critical temperature (50°C was assumed in this study) at maximum depth of 4 cm. In flaming operations, because of short period heating time, depth of heat diffusivity was limited to 12 mm and this condition was not harmful for micro organism at lower than 7 mm. The results of this study can be used for understanding the mechanism of short-time heat transfer in shallow field soil and increase our knowledge about the condition of thermal rate diffusivity. Also the derived graphs trom the model can be used to estimate the harmful condition in residual burning and flaming. Also, the field conditions can be managed for minimum damage of soil micro organism during those thermal treatments.

Knowing soil hydraulic properties and their applications in soil water flow models play an important role on solving many water management issues. Unsaturated soil hydraulic conductivity (Ku), probably is considered the most important parameter in this category. Currently, there are numerous models for estimating Ku. In this study, Ku was measured for three sites with different soil textures using instantaneous profile (internal drainage) method of Hillel et al. (1972) for a 45-day period. Then, the performances of four Ku predicting models 1) Rawls and Brakensik (1989), 2) Vereeken et al. (1990), 3) WDsten (1997), and 4) Wosten et al. (1999) were investigated. Soil moisture was measured for 10 cm layers by using a calibrated TDR. A final depth of 60, 60, and 30 cm was adopted for the three sites under study. Corresponding suction for each moisture value was estimated through relevant soil moisture retention curve (SMRC) which was determined in the laboratory using undisturbed samples by sand table and pressure plate apparatus. A statistical test was conducted between measured and predicted values. The results showed that due to high sensitivity of Ku to saturated hydraulic conductivity (Ks), two models of Wosten (1997) and Rawls and Brakensik (1989) performed better than others when Ks is estimated by the samemodels.

In a field experiment in Varamin Agricultural Research Center during 2003 to 2004, effects of three irrigation water regimes based on evaporation from pan class A (60, 80and 100 percent evaporation) and four fertilizer treatments (NPK, NPKZn, NPKFe and NPKFeZn) in a clay loam soil on tomato yield were studied. The experiment design was split plot with three replications using drip irrigation. Main plots included irrigation regimes and sub plots included micronutrients treatments. Results showed that the effects of main plots and sub plots and their interaction on yield and water use efficiency were significant. Results showed that use of Zn and Fe increased yield and water use efficiency significantly. In general, use of NPK+Fe+Zn and irrigation based on 100% evaporation based on evaporation pan was best treatment with 48.1 ton. ha-1 fresh yield production and 6.2 kg. M-3 water use efficiency.

Floodwater spreading stations have been established with different goals. that enhance our understanding of some unknowns and suitable programming for reaching them, can present clear resplendence for future. For these purposes, this study was done to evaluate of some of physical-chemical characteristics change of topsoil in Zanjan floodwater spreading station. A plot in 100x80 m in control site and 3 plots in 500x80 m in spreading site were selected. The infiltration of topsoil was measured by double ring method. The pH, EC, TNV%, P, K, O.C and soil texture in depth of 30 cm was also measured. The results showed that infiltration rate decreased on spreading site, so, its difference with control site was statistically significant at the 1% level. Increase O.C was observed in spreading site compared with the control site. The amount of O.C and silt decreased significantly from up to down of spreading site. Also, within each plot of spreading area the values of infiltration, silt and O.C increased along the slop up to down (from spreading channel to next channel embankment).

The natural resources of the country have been seriously damaged in recent decades and resulting many dire consequences such as water deficiency, floods and land degradation. In this research, in order to study the effects of open grazing management and alfalfa cultivation on runoff generation, the Matash region located in Talesh mountainous spring-fall rangeland with area of 500 ha was selected. To achieve the study objectives, three plots in dimensions of 1.8322.18 meters were established in three replications in each area. The results of storm water among replications and in two abovementioned areas were then compared using ANOVA and paired sample t-Test, respectively. The relationship between vegetation variations and rainfall characteristics was also investigated in terms of runoff generation in two study treatments. The results have shown that there is a significant difference in runoff generation in two above-mentioned areas at the confidence level of 99%, whereas no significant difference was found among replications. The results of runoff generation was also found to be 5.5 folds more in case of open grazing treatment comparing with those generated by planted plots. From the results of regression analyses and the amounts of estimation errors, it has been also implied that runoff quantity could be significantly affected by rainfall only under open grazing plots.

The effects of deficit irrigation on yield, yield components, and water use efficiency (WUE) of three cultivars of early corn (301, 303, and 315) were evaluated at Varamin agricultural research institute. The experimental plots were irrigated by a line -Source sprinkler irrigation system. Six different levels of irrigation depth were considered at each sides of the lateral and treatments were replicated three times along the length of the lateral. The results indicated that corn yield and yield components decreased significantly due to deficit irrigation, but, the responses of the cultivars to deficit irrigation were not the same. The production functions of each one of the cultivars were found. Yield response factor (Ky) were found to be1.43, 1.35 and 1.37 for 301, 301 and 315 cultivars, respectively. The highest WUE was not obtained from I6 irrigation level, but from I5 for 301 and 303 cultivars and from I4 for 315 cultivar. Cultivar 315 had the highest WUE as compared with the other two cultivars. Variations of relative yield reduction and production efficiency at different irrigation levels for each of three cultivars were approximately the same. In average, as compared with I6 treatment, in response to 1% moisture reduction, yield decreased relatively 1.4%.