Iranian Journal of Soil Research
Year:2002 | Volume:16 | Issue:1|Papers Count:12

In order to evaluate the computerized fertilizer recommendation model developed by the Soil and Water Research Institute for wheat, an experiment was conducted in Golpaygan area designed in four treatments. T1= Control; T2= Computerized recommendation; T3= 30 percent less than T2; T4= 30 percent more than T2 + 150kg potassium sulfate (SOP). This trial was designed in randomized complete block with four replications in three different regions with two different water sources, in sodic/saline soil conditions. The trial was conducted in agricultural year 1998-99. The concentrations of N, P, and K in the first plot were 0.1 percent, 6.2 and 400 mg/kg. In the second plot the values were 0.1 percent, 6.0 and 430 mg/kg respectively, and in the third plot the values were 0.1 percent, 26.2 and 780 mg/kg respectively. Electrical conductivity for water in the first and the second plots was 4.54 and for third plot was7.36 dS/m. Analysis of treatments showed that fertilizer treatments had a significant difference with the control. Grain yield in T1 was 863 kg/ha and in T2, T3 and T4 were 3942, 2321 and 4418 kg/ha respectively. All treatments were significantly different from the control and the difference between T1, T2, T3 was significant (P=0.01) but the difference between T4 and T2 was not significant (P=0.05). The weight of 1000 grains difference between treatments and control was significant. It was 32.52 gr in T1, and in T2, T3, T4 were 46.36, 38.83 and 49.93 and was significant (P=0.05) between T2 and T4. Protein content was higher in treatments in comparison with the control and between T4 and control the difference was significant. Protein percentage in control was 12.6 and in T2, T3 and T4 were 13.45, 13.49 and 13.88 respectively. Nitrogen percentage in the straw was higher in treatments than control, but the difference was not significant. Nitrogen percentage in straw in the control was 0.30, and in T2, T3, and T4 were 0.37, 0.35, 0.44 respectively. Chloride, P, and K concentrations in grain were not significantly different between treatments and the control

A greenhouse study was conducted with 12 treatments and 5 replications. The experimental design was a complete randomized design. The treatments were (1) nitrogen and phosphorous (control) (2) 1st treatment + micronutrients, (3) 2nd treatment + 100% K requirement from KCl source, (4) 2nd treatment + 100% K requirement from K2SO4 source, (5) 2nd treatment + 150% K requirement from KCl source, (6) 2nd treatment + 150% K requirement from K2SO4 source, (7) 2nd treatment + 200% K requirement from KCl source, (8) 2nd treatment + 200% K requirement from K2SO4 source, (9) 2nd treatment + 200% K requirement from 505 KCl and 50% K2SO4 sources, (10) treatment 9 + soil incorporated MnSO4 (11) Treatment 10 + foliar application of complet micronutrients, and (12) Treatment 1 + foliar application of CaCl2. The results indicate tha all K treatments increased the yield significantly at 1% level. Treatment 11 and 12 had the highest yields. The quality components and shelf life of the carnations were significantly improved compared with control 1% level, in all treatments. The treatments with 15% K fertilizer recommendation had the best effect on quality components. There was no significant difference between the two types of K fertilizers. The leaf concentrations of Ca and Mn were reduced significantly in all K treatments. Treatments 7 and 8 had the highest reductions. From the results of this experiment, it is concluded that for the highest number of carnation flowers per plant, the 150% K fertilizers recommendations are the best

In a field experiment, changes in pH, SAR, ECe and biological activity of a sodic soil were studied following the application of organic matter, mineral compounds and combinations of these materials. Experimental design was RCBD with three replicates and the treatments included wheat straw and manure applied at rates of 10, 20 and 40 t/ha, sulfuric acid and gypsum (equivalent to gypsum requirement), cement (5 t/ha), and a combination of wheat straw and manure at a rate of 20 t/ha mixed with gypsum or cement. Results of the experiment one and four months after application of the treatments showed that both sulfuric acid and gypsum significantly decreased soil pH. Sulfuric acid decreased pH from 8.37 to 7.87 and 7.60 after one and four months, respectively. However, application of gypsum decreased pH to 7.93 after one month and this remained constant thereafter. Straw (excluding 40 t/ha treatment) manure and cement had no significant effects on soil pH, but application of straw and manure with gypsum, significantly lowered pH after four months. Addition of sulfuric acid to irrigation water, gypsum, and organic matter with gypsum increased ECe and soluble calcium in saturated soil extract significantly. The highest decrease in SAR was obtained four months after the application of gypsum and sulfuric acid. Addition of gypsum to soil had better effect on decreasing the SAR than gypsum mixed with organic matter. This suggests that organic matter lowered the positive effects of gypsum in decreasing the SAR of the soil under study. Following the application of different levels of straw, biological activity (measured as evolved CO2) increased significantly. The highest increases were for 40 t/ha of straw, which raised the biological activity to over 3.5 times compared with the control. This treatment increased evolved CO2 from 46.4 in control to 166.8 mg m-2 h-1. Different levels of manure also increased biological activity, but the effects of manure were much lower. Differences between the rates of manure and straw were statistically significant. Based on these results, it may be concluded that application of plant residues, which have a higher carbon content than manure, is more effective for increasing biological activity of sodic soils. Furthermore, we found that addition of gypsum to organic matter decreased the rate of carbon mineralization probably due to increasing EC of soil solution. It may be concluded that for the maintenance of organic matter in sodic soils, these materials should be applied in mixture with gypsum.

Limited information is available on the application of potassium fertilizer in arid and semi-arid soils, because these soils are generally well supplied with plant available potassium. But, soils that have been intensively cropped are becoming depleted in plant available potassium. The objectives of this study were to (i) investigate the effect of potassium fertilizer on the changes in solution and exchangeable potassium and (ii) determine if any of the changes can be attributed to the some physical and chemical property of the soil. Fifteen surface soils were equilibrated at field capacity for three weeks after additions of 0, 21, 42, 104, 208, 415, and 1245 mg K kg-1 of soil. Solution potassium was linearly increased with potassium addition. Also a linear increase in exchangeable potassium with potassium addition was observed. The value of slope representing the proportion of added potassium displaced from exchange sites with ammonium acetate varied from 0.55 to 1.03. Values larger than 1 indicates more exchangeable potassium was displaced from the soil than had been added, whereas values less than 1 shows some fraction of added potassium was fixed into forms that were not extractable with ammonium acetate. The coefficients describing the relation of both solution and exchangeable potassium were not correlated with any of the measured soil properties.

It is speculated that leaf apoplastic pH plays a role in iron absorption by cells. In this experiment, the effect of foliar application of sulfuric acid on leaf chlorophyll content of Jahrom local orange (Citrus sinensis) was investigated. The rootstock was sour orange (Citrus aurantium). The trial was carried out on a calcareous soil. Reports of leaf analysis in the region show normal amounts of iron in spite of the iron chlorosis symptoms of leaves. Also, the interaction of this treatment with application of Sequestrine 138-Fe (Fe-EDDHA) fertilizer to the soil was investigated. The experiment was conducted using split plots with randomized complete block design. The main factor was Sequestrine 138-Fe fertilizer at three levels 0, 75, and 150 gram per tree. The other factor, spray of sulfuric acid solution, had three pH levels of 3,5, and 6.6; the latter being distilled water as control. Sulfuric acid was used to reduce pH of distilled water to 3 and 5. The experiment had four replications and two trees per subplot. Total number of trees in this study was 72. Results of our study show that the effect of foliar application of sulfuric acid on leaves chlorophyll content was not significant. Also its interaction with Sequestrine 138-Fe fertilizer was not significant. Also, there was no significant difference between the levels of Sequestrine 138-Fe application. According to the results of this experiment, the pH levels of sulfuric acid solution sprayed two times during the germination had no effect on leaves chlorophyll contents. It is possible that lack of significant difference between two levels of Sequestrine 138- Fe, 75 and 150 gram per tree, was due to the resistance of the sour orange rootstock to iron chlorosis on calcareous soils

Soil pH has become acidic in large areas of tea plantations in Iran (pH<4). The main reasons for this change are: rainfall, leaching, acidic parent materials, and use of chemical fertilizer containing ammonium ion for a long period. High acidity of soil causes deficiency and toxicity of some nutrients, nematode spreading and decreasing in yield. Regard to importance of pH of soil and its optimum value for tea growth (pH=5-5.5), it is necessary to increase the pH level in soil using suitable and available amendments. The aim of this study was changing the pH to optimum level in soil. Two kinds of calcareous materials (i.e. local limestone and seashell) were applied to increase soil pH in tea plantations. The amount of lime requirement was calculated using Foth equation, [pH 24=187-0.3CEC-HSP] with respect to provide optimum value of pH and CEC of soil. The study was carried out in a factorial experiment as a completely randomized design. The amounts of limestone powder were 1.34, 2.69, 4.07 and 8.14 gr per kg soil and for sea shell powder were 0.95, 1.89, 2.87 and 5.74 gr per kg of soil for increasing the pH of soil from 3.5 to 3.9, 4.4, 4.8 and 6.1, respectively. The pH was measured 1,2,3 and 6 months after application of lime in each pot. The results showed that both compounds increased the soil pH to optimum value in an interval of 1 to 6 months and there was no difference between the treatments.

The species of Pseudomonas fluorescens is an important kind of Plant Growth Promoting Rhizobacteria (PGPR). In this research, the native strains of this bacterium, which were isolated from different fields under wheat cultivation, were investigated for their plant growth promating potentials. For this purpose, two sets of experiments were conducted under greenhouse conditions using sterile and none sterile field soil under fallow in a randomized complete block design (RCBD) with four replications. Treatments included inoculation with 22 individual strains (B1 to B22) and one set of multiple strains (B23) in sterile soil and 39 individual strains (B1 to B39) and one set of multiple strains (B40) inoculum in nonsterile soil. Each soil had a set of uninoculated control(B0). Seeds of spring wheat, Moghan 1 variety, were germinated under sterill conditions and then planted in the pots.During growing period, the pots were irrigated with distilled water to maintain soil moisture around 0.8 Fc. Three weeks after cultivation, the height of all seedings were measured. At harvest time, the height number of tilers and heads and dry weight of seeds and shoots were determined. The data were analyzed using MSTATC program. Greenhouse studies showed a positive response of wheat to inoculation with different native strains of P.fluorescens in most cases. In sterile soil, inoculation mostly affected plant he at an early growth stage. The inoculated seedlings were significantly taller than control (P<0.01). In non-sterile soils, The significant increases were obtained for plant hight (P<0.05) and number of heads (P<0.01) In both soils, the effect of inoculation was also pronounced for the number of tillers and significant increase (P<0.05) was observed at least in some bacterial treatments as compared with control.

Land suitability evaluation has been determined for irrigated wheat, sugarbeet and alfalfa in an area about 5600 ha in Piranshahr region in West Azarbaijan Province. In order to have more reliable soil data, particularity to control the old soil map of the area, a new soil survey was carried out in the area. Soils were classified based on soil taxonomy (1998) and five families and nine phases were identified. Climatic data from Piranshahr synoptic meteorological station have been used for climate evaluation of crops. Based on yield coverage and climatic conditions, wheat, sugarbeet and alfalfa have been considered and compared in the present land suitability evaluation on the basis of irrigated agricultural system. In this region, the most important limiting land characteristics have appeared to be topography and flooding. In surveyed area, the climatic classes are suitable (S1) for wheat and sugarbeet and moderately suitable (S2) for alfalfa. Analysis of rainfall and ETO data reveals that the growing period is about 112 days, starting on November 20 until July 11. Comparing the two parametric methods (i.e. storie and square root methods) for determination of land indexes for three crops, in all methods the land indexes for wheat was always higher than those for sugarbeet and alfalfa, the square root method was considered to be more realistic for land suitability evaluation in the studied areas

Few studies have been done on soils of Gilan province in northern Iran, although the area enjoys high potential for agricultural production and has vast forested regions. To study the effect of time on the formation of soils in the area, physical, chemical and micromorphological properties of four soils on flood plain and three upper terraces of Sefidrud River was investigated in this study. Different size fraction of sand, silt and clay were separated by centrifuge. Lithologic discontinuity was determined by performing similarity index test on different horizons, using eight size fractions of sand and silt. Crystalline, amorphous, and organic iron was extracted using CBD, ammonium oxalate and sodium pyrophosphate respectively. The increase in difference between oxalate extracted and CBD extracted iron (Fed-Feo) from lower flood plain to highest terrace soils indicates increase in crystalinity of iron and also soil profile development. At the same time, the ratio of (Feo/Fed) decreases toward the upper terrace soil that is also indication of increase in soil development and relative soil age. Other factors such as organic matter and CEC increase and pH and base saturation decrease toward the upper terrace soil. As a result of increase in relative soil age and decrease in soil pH from soils of flood plain to middle (T2) and upper terraces. Chlorite is transformed to smectite, hydroxy interlayer smectite and other mixed minerals. In the middle terrace (T2) soil, chlorite is completely disappeared but the relative amount of smectite is increased. Three different methods were tested to remove hydroxy interlayers from 2:1 clays, but only one of these methods which consisted of washing coarse clay fraction by 0.05 M HCl, heating to 400oC and finally boiling it in 0.5 M NaOH was able to remove hydroxy interlayers. The results showed this mineral is primarily hydroxy interlayer smectite (HIS). The presence of lithologic discontinuity in the middle and the upper terraces, which was shown by similarity index test, indicates that contrary to previous beliefs, these soils are formed on alluvial rather than eolian deposits.

Scarcity of water is one of the limiting factors for the expansion of agricultural production in Iran. Therefore, management of available irrigation water is very important in order to increase water use efficiency and to prevent loss of irrigation water. Olive (Olea europaea L.) is one of the drought resistance plants. Considering the adaptability of olive plants to areas faced with shortage of water, the cultivation of olive plants is encouraged by the fruit industry. Five-month old rooted cuttings of olive plants cv. Zard transplanted in 5.4- liter polyethylene pots were subjected to different irrigation regimes during the growing season. Treatments were 20, 40, 60, 80 and 100% of potential evapotranspiration (ETp) of olive plants, which are referred to by I1, I2, I3, I4, and I5 respectively. The water use of five pots which were irrigated once in every three days were considered as olive cuttings ETp. The irrigation frequency of all pots was three days. Vegetative growth was reduced by increasing water stress during the growing season. In general, root, shoot and leaf fresh and dry weight, leaf number, leaf area, plant height, shoot number and shoot length were decreased as the intensity of water stress increased. The differences between treatments in various measured characters were significant except for shoot number with less than 10 cm length. Plants subjected to I4 and I5 treatments, did not show any significant differences for leaf number, leaf area, plant height, shoot number and shoot length. Plants in I1 and I2 treatments did not show any vegetative growth and also leaf abscission was occurred in these plants. Although, leaf abscission was did not occur in plants in I3, I4, and I5 treatments. Results indicate that plants subjected to I4 and I5 treatments had a better growth and performance than plants in the other treatments.

The increasing demand for food as a result of population growth has led to more pressure on the limited water resources for irrigation. For this reason, increase of yield per unit of water is the more important as compared with yield per unit of land. A field experiment was conducted in Bonab to estimate water requirement of wheat and to determine the effect of various irrigation regimes on yield components, water use efficiency, changes of salts in the soil profile, and to obtain a method for irrigation scheduling by using readily available information. This experiment was conducted in randomized complete block design with four treatments (I1 to I4) and in four replications. Irrigations were applied based on the ratio of irrigation water depth to cumulative pan evaporation (ID/CPE). Irrigation water depth was taken equal to half of available water in rooting zone and constant for all treatments. Irrigations were initiated when ID/CPE reached to 0.4, 0.6, 0.8 and 1 in treatments I1 to I4, respectively. Results indicated that there were significant differences in biomass and grain yield between treatments and treatment I4 with 13.08 ton ha-1 biomass and 5.27 ton ha-1 grain yield and treatment I1 with 8.84 ton ha-1 biomass and 3.21 ton ha-1 grain yield had maximum and minimum yield respectively. Amounts of water used by the treatments from I1 to I4 during growing season were 1396, 2966, 3684 and 4526 m3 ha-1 respectively. There was a significant difference in water use efficiency (WUE) between I1 and other treatments but there was no significant difference between I2, I3 and I4. On the basis of WUE, treatment I1 with 2.26 kg m-3 and I4 with 1.163 kg m-3 had maximum and minimum WUE respectively. On the basis of 1000-grain weight and harvest index (HI), there were significant differences between treatments. Treatment I3 with 46.19 gr and I4 with 41.19 gr had maximum and minimum 1000-grain weight respectively and treatment I4 with 0.404 and I2 with 0.352 had maximum and minimum HI between treatments respectively. There was significant difference in protein content between treatments and treatment I22 with 16.23 % and treatment I1 with 13.87 % had maximum and minimum protein content respectively. Because of differences in amount of applied water between treatments, soil salinity profile was different between treatments after harvest so that salt concentrated layer in treatments I1 to I4 was in depth of 15-35, 15-35, 35-50, and 50-100 cm respectively.

Few studies have been done on soils of Gilan province in northern Iran, although the area enjoys high potential for agricultural production and has vast forested regions. To study the effect of time on the formation of soils in the area, physical, chemical and micromorphological properties of four soils on flood plain and three upper terraces of Sefidrud River was investigated in this study. Different size fraction of sand, silt and clay were separated by centrifuge. Lithologic discontinuity was determined by performing similarity index test on different horizons, using eight size fractions of sand and silt. Crystalline, amorphous, and organic iron was extracted using CBD, ammonium oxalate and sodium pyrophosphate respectively. The increase in difference between oxalate extracted and CBD extracted iron (Fed-Feo) from lower flood plain to highest terrace soils indicates increase in crystalinity of iron and also soil profile development. At the same time, the ratio of (Feo/Fed) decreases toward the upper terrace soil that is also indication of increase in soil development and relative soil age. Other factors such as organic matter and CEC increase and pH and base saturation decrease toward the upper terrace soil. As a result of increase in relative soil age and decrease in soil pH from soils of flood plain to middle (T2) and upper terraces. Chlorite is transformed to smectite, hydroxy interlayer smectite and other mixed minerals. In the middle terrace (T2) soil, chlorite is completely disappeared but the relative amount of smectite is increased. Three different methods were tested to remove hydroxy interlayers from 2:1 clays, but only one of these methods which consisted of washing coarse clay fraction by 0.05 M HCl, heating to 400oC and finally boiling it in 0.5 M NaOH was able to remove hydroxy interlayers. The results showed this mineral is primarily hydroxy interlayer smectite (HIS). The presence of lithologic discontinuity in the middle and the upper terraces, which was shown by similarity index test, indicates that contrary to previous beliefs, these soils are formed on alluvial rather than eolian deposits.