JWSS - Journal of Water and Soil Science

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Most part of the applied phosphorus is fixed in the calcareous soil. Some part of residual phosphorus can be recovered by the plants of the following years. It is reported that organic matter is one of most important factors in phsphorus recovering. This expriment was designed in permanent plot to evaluate the effect of organic matter on residual phosphorus recovering in a calcareous soil. The expriment was conducted on randomized complete block design in a factorial manner with three replications in four years. Treatments were consisted of farm yard manure(FYM) in three levels ( 0, 15, and 30 ton ha-1) and three levels of phosphrus ( 0, 90 and 180 kg ha-1 as P2O5 from triple super phosphate (TSP). Phosphorus fertilizer was applied only in the first year of expriment, but FYM was used in all of the years. Onion, canola, bean and spinage were planted in the four years of experiment, respectively. Results showed that maximum yield, P concentratin in plant and soil phosphorus availability were followed by application of FYM and P(residual) together in all of the years. This increase was mainly by direct effect of P in the first year of expriment, but recovered phosphrus by FYM had maximum role in the later years. More than 53% of increase in phosphrus availability in soil and 21% of increase in yield resulted from recovered phosphprus by FYM in the treatment of 30 ton.ha-1 FYM and 180 kg.ha-1 P2O5 together in the last year.

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Phosphorus is often considered the most limiting soil nutrient for plant productivity. Several extractants have been typically used to measure available P. Organic and inorganic P fractions are not measured by common soil test, and thus fractionation schemes using various extractants have been developed over years to quantify the different chemical forms of P in soils. The objectives of this research were: i) to investigate the effect inorganic P fractions on Phosphorus availability ( Olsen procedure), and ii) to evaluate the relationships between these P fractions and Garlic (Allium sativum) plant indices. Soil inorganic P fractions were determined in 30 surface soil samples (0-30 cm) from various regions of Hamedan Province. Inorganic P fractions included dicalcium phosphate (Ca2-P), octa calcium phosphate (Ca8-P), P adsorbed by Al oxide (Al-P), P adsorbed by Fe oxide (Fe-P), P incorporated into Fe oxide (O-P), and apatite (Ca10-P). Total P and Organic P were measured in these soils. In order to evaluate the availability of different forms of P to plant, a pot experiment was conducted on Garlic plant. The treatments including two rates of P (zero and 150 mg kg-1) and 9 soils from 30 soil samples were arranged in a factorial experiment in a completely randomized design with three replicates. The results showed the total P with an average of 1501 mg kg-1 soil, and organic P comprised 19 % of the total P. The inorganic P fractions (Ca2-P), (Ca8-P), (Al-P), (Fe-P), (O-P), (Ca10-P) and residual phosphate (Res-P) comprised 4.7, 20, 8.7, 3.0, 2.8, 24 and 18 % of total P, respectively. Most of the inorganic P occurred as Ca-P and comprised 49% of total P. The correlation study between different P fractions showed that Ca2-P, Ca8-P, Ca10-P, and Al-P were significantly correlated with Olsen-P. This suggested that probably Olsen procedure essentially removed some P from these fractions. The results of pot experiment indicated that plant indices (relative yield and Yield efficiency) were significantly correlated with Ca2-P, Ca8-P and Olsen-P (P ≤ 0.05). P availability in the studied soils was influenced by Ca2-P and Ca8-P which could be used in a long period of time by plant.

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Effect of drought stress and mycorrhizal symbiosis on growth and phosphorus (P) uptake by two sorghum cultivars different in root morphology was studied in a pot experiment. A factorial experiment with a randomized complete block design was performed. In this study, sorghum speed feed cultivar with high root proliferation and branching and sorghum KFS2 cultivar with low root proliferation and branching were colonized by Glomus intraradices. All plants were watered equally in the first three weeks to establish them. Drought stress was applied from the week four and the plants were watered when 40% (T1), 60% (T2) and 80% (T3) of the available water was consumed. Results showed that in both sorghum cultivars, plant dry weight decreased as drought stress was increased. However, dry weight of mycorrhizal plants was higher than that of non-mycorrhizal plants at all levels of drought stress. This increase for speed feed cultivar was greater than for KFS2 cultivar. Phosphorus concentration and total P uptake in shoot of both mycorrhizal plants were greater than those of non-mycorrhizal plants. P accumulation in both cultivars decreased by increasing drought stress due to the decline in plant biomass. However, P accumulation per unit length of colonized root increased by increasing drought stress. The greater percentage of root colonization and the increased total length of external hyphae per unit length of colonized root of KFS2 cultivar led to an increase in mycorrhizal growth response and improved P nutrition of KFS2 cultivar compared to those of speed feed cultivar.

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Azotobacter chroococcum can improve mineral nutrition of plants through N2 fixation and plant growth promoting capabilities. Fourteen strains of A. chroococcum were isolated from rhizosphere of wheat plants grown in different field conditions around Tabriz, northwest of Iran. In a pot culture experiment with sterile soil, wheat plants (Triticum aestivum cv. Falat) were inoculated with 14 bacterial strains. Positive control received nitrogen fertilizer without bacterial inoculation and the negative control was left un-inoculated and without N- fertilizer. Totally, 16 trearments with four replications were arranged in a completely randomized design. The plant growth indices and N and P concentrations of shoot and root were determined at the harvest time. Results showed that the inoculation with Azotobacter strains caused a significant increase in shoot and root dry weights. Bacterial inoculation significantly enhanced the concentration and content of N in shoot and root. Phosphorus content was only enhanced (p<0.05) in the root. Translocations of N and P from root to shoot were markedly increased in bacterial treatments compared to the positive and negative controls. Moreover, strains 1 and 48 which showed relatively higher phosphate solubilizing capability and phosphatase activity in in-vitro assay also brought about higher P content and concentration in shoot and its translocation from root to shoot.

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Contamination of agricultural soils by heavy metals is a serious threat from both agricultural and environmental standpoints. Among heavy metals, cadmium (Cd) toxicity for humans and plants is of great concern due to its high mobility and phytoavailability in soil even at low concentrations. Opposite to Cd, Phosphorus (P) is an essential nutrient for plant growth. A greenhouse experiment was carried out in a completely randomized design to examine the influence of Cd, P and their interaction on the growth and chemical composition of spinach grown on a calcareous soil. Treatments consisted of four Cd levels (5, 10, 20 and 40 mg/kg soil as cadmium sulfate) and four P levels (0, 20, 40 and 80 mg/kg soil as mono-calcium phosphate) in three replicates. The results indicated that 40 mg Cd significantly decreased spinach dry weight by 47% but P application decreased detrimental effect of Cd on spinach dry weight. Also, phosphorus application significantly decreased Cd concentration in spinach aerial parts by 78%. Increasing Cd levels increased concentration of this element in spinach shoots. Addition of 40 mg Cd decreased P concentration by 21.5% in aerial parts. Zinc (Zn), manganese (Mn), calcium (Ca), and nitrogen (N) concentration significantly decreased with P application but increased concentration of sodium (Na). Cadmium application decreased Zn concentration but increased Ca, Na and N concentrations in spinach. Our tentative conclusion is that P application in P-deficient soils is probably effective in decreasing Cd concentration and the detrimental effect of Cd on spinach growth, indicating a negative interaction between these elements. Prior to any fertilizer recommendation, the results of this experiment should be verified under field conditions

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Organic acids can affect phosphorus (P) sorption. In order to evaluate the effect of citric acid and oxalic acid on phosphorus sorption characteristics in calcareous soils, five different soil samples (0-30 cm) were collected in West Azerbaijan province. Soil samples (2.5 g) were equilibrated with solutions of KH2PO4 containing 0 to 20 mg P l-1. Five mM organic acids were added to each tube and sorbed P was calculated. The sorption data were fitted to Langmuir, Freundlich and linear equations. The results showed phosphorus sorption data were well described by the Freundlich and linear equations. The average values of Kf (distribution coefficient), n and equilibrium buffering capacity (EBC) of linear equation in citric acid treatment were reduced to 29, 12 and 17 percent, respectively and for oxalic acid reduced to 43, 27 and 14 percent, respectively. Maximum sorption was reduced significantly by oxalic as compared to citric acid. Standard phosphorus requirement (SPR) was decreased by 57 % as a result of organic acids additions compared to control condition. It is concluded that organic acids additions to soils containing more calcium carbonate and high amount of clay can decrease P sorption.

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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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Application of sewage sludge has been considered as an organic fertilizer in arid and semi-arid regions of Iran. This study was conducted to investigate cumulative and residual effects of sewage sludge on soil inorganic fractions and their relation to phosphorus (P) availability. Two levels of application (50 and 100 Mg ha-1) and three consecutive times of sewage sludge application (1, 3 and 5 years) with a control treatment were studied in a randomized complete block split plot design with three replications. Composite soil samples were collected from 0-30 depth at the end of 5th year of application. Increasing the rate and application year of sewage sludge enhanced dicalcium phosphate (Ca2-P), octacalcium phosphate (Ca8-P), apatite (Ca10-P), aluminum phosphate (Al-P), iron phosphate (Fe-P) and available P but decreased occluded P (OC-P). Residual effect of sewage sludge application resulted in increased inorganic fractions in blocks treated for 1 year compared to control. Positive correlations were observed between inorganic P fractions and Olsen P, wheat yield and P uptake (except OC-P). We concluded that inorganic P fractions and P availability increased in sewage sludge amended soil.

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To study the effects of soil phosphorus (P) application on growth and water relations and nutrient concentration of pistachio seedlings (Badami-e-Zarand) under water stress, a greenhouse experiment was conducted. Treatments were arranged in a factorial manner as a completely randomized design with three replications. Treatments consisted of six P levels (0, 30, 60, 90, 120 and 150 mg P Kg-1 soil as H3PO4) and three irrigation intervals (2, 4 and 8 days). Results showed that as water stress increased, growth parameters significantly decreased. As irrigation interval was increased to 8 days, shoot and root dry weights, shoot/root ratio, leaf area and leaf number and stem height decreased. Photosynthesis parameters were significantly decreased by increasing water stress. Also, P and Zn concentrations decreased as irrigation interval increased. Analysis of variance indicated that P application had no significant effect on growth parameters, transpiration rate and photosynthesis. It seems that Olsen extractable P (5.35 mg kg-1 soil) was sufficient for optimum growth of pistachio seedlings and thus, no growth responses were observed from P application in this experiment. Application of phosphorus significantly increased P and decreased Zn concentrations.

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Phosphorus behavior in waterlogged soils is significantly different from non-waterlogged soils. Changes in available phosphorus and inorganic phosphorus fractions after waterlogging in the paddy soils of north of Iran were studied in a laboratory research. A factorial experiment in a completely randomized design with two replications was performed with factors of soil at 14 levels (10 alkaline-calcareous and 4 non-calcareous or acid soils) and duration of waterlogging period at three levels (0, 30, 90 days). At the end of waterlogging period, phosphorus fractions in calcareous soils by Jiang and Gu method and in non-calcareous soils by Kuo method and available-P by Olsen method were determined. The results showed that the level of available-P in all soils was increased 90 days after waterlogging (on the average 2.3 times). In general, all P fractions were changed significantly after waterlogging and the amount of change was different depending on P fraction, soil type, and duration of waterlogging period. These results indicated the complex behavior of P in soils. The Al-phosphates were increased in 12 out of 14 calcareous and non-calcareous soils 90 days after waterlogging compared with air-dry soil. The Fe-phosphates were decreased in 9 out of 10 calcareous soils 90 days after waterlogging compared with air-dry soil while the effect of duration of waterlogging period on the Fe-phosphates in non-calcareous soils was not significant. The readily soluble-P in non-calcareous soils increased 30 and 90 days after waterlogging. The results indicated that some inorganic P fractions transformed into other fractions and probably organic P transformed into inorganic P during soil waterlogging period.

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Evaluation of chemical and biological indicators of soil in different land uses could be helpful in sustainable range management, preventing degradation of soil quality trend. This study was conducted in Friedan in Isfahan province in 2010 to compare chemical and biological indicators in three land uses (rangeland, degraded dry land and dry land), during two growing seasons (May and September) in three slopes (0-10, 10-20, 20-30 %). Nitrogen, phosphorus, potassium, organic matter, cation exchange capacity and microbial soil respiration were measured. Results showed that all measured characteristics except potassium decreased over an increase in the slope. Maximum values of phosphorus, organic matters, cation exchange capacity and soil respiration were obtained in pasture (28.4 mg/kg, 0.62%, 20.38 cmol/kg, 33.2 mgC/day, respectively)but potassium maximum rate was seen in dry land form (406.8 mg/kg).The effect of season on all measured parameters was significant except for N, while the highest amounts of phosphorus, potassium, cation exchange capacity and soil respiration (28.7 mg/kg, 377.3 mg/kg, 19.6 cmol/kg and 25.9 mgC/day, respectively) were seen in May and the highest organic matter rate (0.68%)in September. The results of this study showed that an increase in the slope, poor range management, and the end of the growing season could be major factors degrading the soil quality indices and soil productivity.

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The ability of different soil tests in predicting soil phosphorus (P) is important in soils amended with municipal sewage sludge. The objective of the present study was to evaluate several chemical extractants to estimate available P for bean growing in 10 calcareous soils amended with municipal sewage sludge from Chaharmahal-Va-Bakhtiari province under the greenhouse conditions. For this purpose, the soil samples were incubated with sludge at a rate of 39-ton sludge ha–1. The amount of available P of the soil samples was determined by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, BrayІ, ІІ, Mehlich І and ІІ methods. A pot experiment in a completely randomized design was conducted to evaluate the bean plant indices. The results showed that the amount of extractable P with the above methods decreased in the following order: Colwell> Bray ІІ> Mehlich ІІ> Olsen> Ammonium bicarbonate DTPA> Mehlich І> Bray І> 0.01M chloride calcium. The extractable P with 0.01M chloride calcium, Mehlich І, ІІ Colwell and Olsen methods correlated significantly with plant indices (P concentration and P uptake). Thus, mentioned methods could be used to estimate plant-available P in the soils amended with sewage sludge.

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The present study was conducted to isolate and identify phosphorus solubilizing fungi and to evaluate their ability through a qualitative and quantitative experiment. An experiment was carried out with 5 soil samples of Koh- Sepid Lar, Kohgyloyeh and Boyer Ahmad province. The ability of isolates was studied in solid and liquid cultures. Quantitative experiment consisted of blank, four fungi isolates and Aspergilus niger, with 3 replications. Two fungi that showed the highest potential in P solubilization were used for identification by ITS- PCR methods. Four of the fungi produced very clear zone on the Pikovskaya culture. The order of soluble P content in the liquid culture was: blank< fungi 4< fungi 3< fungi 2< Aspergilus niger< fungi 1. Two high potential isolates, 1 and 2, were Cladosporium cladosporioides and Eupenicillium rubidurum, respectively. This is the first report about the potential of these fungi to solubilize P.

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Salt cedar is widely spread out in most part of the country but there is lack of information about its symbiosis with arbuscular mycorrhizal fungi. Then, the main objective of this study was to evaluate the symbiosis of AMF with salt cedar and its affectability by distance from river and soil physiochemical properties. For this purpose, riparian Maroon forest width was divided to three locations including riverside area, intermediate area and the area far from river with 200-hundred-meter interval. In each site 10 salt cedars were randomly selected and soil plus hair root samples were gathered from the salt cedar rhizosphere. Our result indicated that root colonization and spore density in the intermediate distance had the lowest and highest values, respectively. These values were significantly different compared to the other two sites. The average root colonization percent in the riverside area, intermediate area and the area far from river sites were 82.37, 73.77 and 80.17, respectively. While the average spore density in the riverside area, intermediate area and the area far from river were 189, 245.5 and 188.8 in five gram soils, respectively. Root colonization had significant positive correlation with soil potassium while spore density had significant correlation with studied soil physiochemical properties. Also, soil nitrogen, organic carbon, potassium and clay showed 52.6, 51.19, 50 and 23.4% decreasing trend from the riverside area to the area far from river. Regarding this research results, salt cedar showed high level of symbiosis with arbuscular mycorrhizal fungi but this symbiosis could be affected by distance from river in riparian forest.

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This study was conducted to investigate the effects of poultry manure (PM) and derived biochars on phosphorous (P) availability and apparent recovery in a calcareous soil. Treatments consisted of four rates of P (0, 30, 60 and 90 µgg-1) and five organic substances (blank, poultry manure and derived biochars at 200, 300 and 400°C). organic substances were incorporated with 400 g of soil at 2% level (w/w). All soil treated samples plus control were incubated for 150 days. Soil P availbility determined at 8 different stage of incubation time period. Phosphorous availability was less in untreated soil samples with organic substances and also decreased with time. Although P recovery from inorganic P fertilizer was high in the early stages of incubation time compared to treated soil samples but decreased with time, if not treated with organic substances. Phosphorus availability and recovery increased with time in PM and biochares treated soil samples. Simultanous application of inorganic P and organic substances decreased apparent P recovery. Negative interaction obsorved between organic substances and high rates of inorganic P fertilizer on P availability. It was concluded that PM biochar prepared at 300°C had the highest effect on adjusting P availability in calcareous soil.

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