نشریه مدیریت خاک و تولید پایدار
سال سوم شماره 1 (پیاپی 5، بهار و تابستان 1392)

Supplying phosphorus demand for plants is possible from two ways: chemical and biological fertilizers. A main amount of phosphorus in chemical fertilizers become unsoluble in soil and out of reach for plants. some sulphur oxidizing microorganisms reduce soil pH and transform phosphorus from unsoluble to soluble form. In order to consider the effect of sulphur and Thiobacillus inoculant on soil pH decrease and increase in ability of phosphorus absorption, a greenhouse experience was carried out in factorial form and Randomized Complete Block Design (RCBD) containg 5 levels of elemental sulphur (200, 400, 600, 800 and 1000 kg/ha) and 3 level of inoculant (without, 5 & 10 gram in pot with 107 bacteria per gram) with 3 replications in 1388-89. The results of variance analysis indicated that the effect of all ingredient on absorption of phosphorus and decrease of pH was significant in 1%. Mean of phosphorus in treatments without inoculant was 21 ppm, however in treatments with inoculant was 28 ppm and resulted to 33.33% increasing and sulphur and bacteria interaction resulted to 165% increase in ability of phpsphorus absorption and soil pH decreased 1.05 unit. Increase in absorption of phosphorus by plant was significant, also increased dry matter of plant but it was not significant and it was because of experience error.

Determination of soil erosion and runoff for soil conservation practice requires dynamic model. The objective of this study was to evaluate EuroSEM (European Soil Erosion Model) to measure runoff, erosion and sediment in part of the sub-northern Karoon watershed. The model used in this research is a single event process-base model for predicting soil erosion and sediment. Actual runoff and sediment discharge was calculated using a metal rectangular weir installed at the outlet. Parameterization, calibration and validation of the model were carried out for simulation and also model efficiency was evaluated by determination of coefficient and ME index. Calibration results (Nov. 26, Dec. 16 storms) indicated that best calibration were achieved by decreasing effective net capillary drive and increasing initial volumetric moisture content for hydrographs and also increasing cohesion of the soil and the value of Manning's n in both the rill and interrill areas and decreasing values describing the detachability of the soil particles by raindrop impact for sedigraphs. Validation results (Mar. 8, Mar. 28, Apr. 21 storms) indicated that EuroSEM model simulated total runoff discharge and peak runoff rate well. Evaluation index showed that model efficiency is moderately well but different index showed different results. The simulated hydrograph and sedigraph follows more closely that of the rainfall intensity than does the observed data. Total runoff discharge varied in the range of 1.22 to 6.37 mm/ha depending on the storm being studied and total soil loss between 2.32 to 18 t/ha. The results of model simulation showed that net erosion increased by decreasing saturated hydraulic conductivity and soil erosion decreased by increasing vegetation cover during Nov. 26 to Mar. 28 in each element. Rill erosion increased from 0.16 to 0.54 and interrill erosion decreased 4.28 to 3.45 ton/ha in growing period, inversely.

Phosphorus (P) is one of the most important nutrient elements for plant growth and it is usually considered as second limiting factor for growth of plants after nitrogen. Phosphate‏ solubilizing microorganisms (PSM) play major roles for supplying soluble phosphate to plants in a more environmental-friendly and sustainable manner. To evaluate the effect of phosphate solubilizing bacteria inoculation on growth of spring wheat cv. "Roshan" and also phosphorus uptake, a greenhouse experiment was conducted in sterile loamy soil in a completely randomized design with three replications. Four bacterial treatments were Pseudomonas putida P13 (P13), Pantoea agglomerans P5 (P5), Pseudomonas fluorescence CHAO (CHAO) and combination of P13+P5 and without inoculation as control. Data analysis on the fresh and dry weight of shoot (in the middle and end of growth), number of spikes and seed, weight of seed, concentration and content of P in shoot (in the middle and end of growth) and seed showed that bacterial treatments increased P concentration and content of wheat shoot (P<0.01), and combination of P13+P5 treatment resulted in highest concentration and content of P. Maximum increase of P concentration and content in shoot (1.8 and 1.14 fold in comparison with control, respectively) were observed in combination of P13+P5 treatment. Application of bacterial treatment did not have any increasing effect on dry matter, even though some parameters such as number of spikes, number of seed and weight of seed in some bacterial treatments (CHAO and P5) had high record compared to the control. Highest record of thousand grain weights was obtained in presence of P13+P5. However, the measured parameters such as fresh and dry weight of wheat and also P concentration and content in the middle of growth were not affected by application of bacterial inoculation. According to the results of this experiment we should expect to see the positive effect of PSM inoculation at the end of wheat growth since in the middle of growth no positive effect of PSM in wheat growth was distinguished.

Biological, physical and chemical characteristics of rhizosphere, especially chemical forms of elements are different in bulk soil. This experiment was conducted to compare different chemical forms of lead and their availability in rhizosphere and bulk soil, in two plants (corn and canola) at two times, (three and six weeks after planting) using planting boxes separated into three zones S1 (rhizosphere), S2 (rhizosphere affected area) and S3 (bulk soil) in green house condition. For assessment of metal fraction changes and their bioavailability, various methods of extraction (distilled water, Ca (NO3)2, DTPA and HNO3) were used. Results showed that water soluble forms of lead in cultivated corn and canola soil were greater than control three weeks after planting. Rhizosphere had no significant effect on Pb extractable with Ca(NO3)2. DTPA extractable Pb in corn and canola rhizosphere, was greater than bulk soil three weeks after planting. Extractable Pb with HNO3 in corn rhizosphere, was greater than other zones and for canola was less than bulk soil six weeks after planting. Amounts of Pb uptake in corn shoot were significantly higher than roots. Changes in lead forms in rhizosphere could be as a result of soil properties and plant species. Lead movement in the rhizosphere showed that increase in exchangeable fraction of metal was due to induced solubility of this element in the rhizosphere compared with bulk soil.

Cation exchange capacity (CEC) measurement is a very expensive and time-consuming method in large scale assessments. It can be an appropriate approach to predict CEC from readily available properties via developing nonparametric models. In the present study, a nonparametric technique has been used for estimating CEC and compared with the most common nonparametric models which is based on artificial neural networks (ANN). 683 soils were selected from central Iran that 120 of them were used as target data and the others (563) were the reference data set. The parameters, clay, silt, sand and organic carbon content were the input independent variables (readily available properties) and the CEC was as an output dependent variable in this work. The results showed that the maximum error (MaxE) in K-NN and ANN techniques were 4.81 and 5.26 cmol+/kg, respectively. Root mean squared error (RMSE) for the K-NN and ANN were 1.51 and 1.53, respectively. This indicated that both methods are able to properly and equally predict CEC. The positive values of mean error (ME) showed that both models tended to underestimate CEC values in samples. The results analysis also showed that the efficiency of models (EF=0.88) were high by the estimation of CEC values in target soils.

Land degradation especially in rangeland ecosystems is a serious danger for ecological health and also can reduce the quality and quantity of soils in this ecosystem and vegetation cover for livestock. Generally land degradation indicators are determined, selected and evaluated for the goal of land management by ecological specialists and scientists. On the other hand, pastoral communities have detailed information about their environment but only a few studies use pastoralists in real evaluating and interpreting land changes monitoring. In the present research two areas were selected in southern and eastern parts of Golestan National Park. Two methods were selected for evaluating degradation indicators: scientific method and local knowledge method. For comparing the values of indicators inside and outside the park in our two study areas, permutation t-test was used. Results showed that in the semi-steppe Dasht rangeland annual vegetation production, litter cover and bare soil were three indicators indicated as significant and sensitive indictors by two evaluation methods and in the steppe rangeland of Mirza-Baylu, total vegetation cover, litter cover, invaders and poisonous plants and also bare soil were significant indicators by two methods of specialists and pastoralists.

Kinetic studies on soil potassium release can contribute to a better understanding of K availability to plants, particularly in soils containing K bearing minerals. The objective of this research is to study the dynamic of nonexchangeable Potassium (NEK) from the whole soil, clay and silt fractions in four different soils of Golestan province through successive extraction with CaCl2 (0.01 M) over a period of 1800h and to study its relation with soil minerals types. The rates of cumulative NEK release were evaluated using the kinetic equations. K release was fast in the earlier periods of the extraction in all soils and its fractions and it is followed with a lower rate to the end of experiment. The NEK release rates were well described through Ellovich, power function and diffusion equations upon the highest determination coefficient and the least estimation standard error. There were illite, chlorite, vermiculite, kaolinite, stratified minerals and quartz, feldspars, mica, chlorite in clay and silt fractions, respectively. Among the soil particle size fractions, clay particle showed the highest amount and rates of K release and Gharesou series with dominant smectite showed the highest K release.

Soil moisture is a function of physical and chemical properties of soils. However, cultivation can change soil moisture availability, by affecting soil properties. In order to evaluate these changes, some soil samples with different textures including clay loam, loam and clay sandy loam were taken from cultivated and noncultivated areas. Then, soil moisture characteristic curves, pore size distribution, particle size distribution, bulk density, organic carbon, calcium carbonate, cation exchange capacity and pH of the soil samples were determined. The results showed that cultivation decreased available water in three soils, but the soil moisture decrease in clay sandy soil was lowest. The cultivation had the lowest influence in changing soil properties such as texture and structure in sandy soils in comparison with other soil textures.

Distribution of the fertilizer with correct method is the important step for achieving the sustainable agriculture. This study investigates the potassium movement in soil in fertigation, drip and furrow irrigation systems with transplanting the radish crop in sandy loam soil. In this investigation a complete drip and furrow irrigation system was designed in the Research Field of Shahrood. Applied potassium was 100 kg/ha. Fertilizer was applied by fertigation method in drip fertigation system. Also in drip and furrow irrigation systems it was applied with basal application method. After field and laboratory analyses, results revealed that in case of drip fertigation, potassium was confined mostly in the upper layers of the soil i.e. at 0-25 cm soil depth and lower concentration of potassium nearly equal to initial concentration was found in the lower layers of the soil i.e. at 25-40 cm soil depth. Another result of study revealed that in drip irrigation, higher concentration of potassium was found in the middle layers of the soil i.e. 20-30 cm depth and lower concentration was observed in the upper and lower layers. In furrow irrigation, major portion of the applied potassium has moved down in the lower layers i.e. beyond 20 cm and has lead to more leaching losses. Further the drip fertigation in three equal splits was the most beneficial treatment for the growth and yield (15200 kg/ha) of Radish, higher water use efficiency (7.4 kg/m3) and high potassium use efficiency (64%) in comparison with hand application of fertilizer with furrow irrigation/drip irrigation.

Using of soil conditioners is a method for retaining and storing the soil moisture in arid and semi arid areas. Application of hydrogels is a solution to increase irrigation efficiency in this area. Super absorbent polymers are conditioner’s group which can absorb precipitation or irrigation water and prevent from water percolation. A completely randomized design research with factorial arrangement and three replications was carried out to evaluate the effects of stockosorb hydrogel and irrigation intervals on growth of haloxylon seedlings in Hossain Abad Ghinab (Birjand, Iran). The experimental treatments consisted in different amounts of stockosorb hydrogel (0, 0.1, 0.2, 0.3 and 0.4%) and irrigation intervals (every day, every 3 days and every 5 days). The result showed that application of hydrogel had the positive and significant effect on growth indices of seedling i.e. height, wet and dry weight of shoots and root and root length. The highest values of above indices were noted in 0.4% hydrogel treatment, but most growth indices in this treatment had no significant difference with 0.3% treatment. Also, the maximum values of growth indices were obtained by every 3 days irrigation. In addition, using hydrogel improved some soil properties, so that due to hydrogel, available water content increased and electrical conductivity and bulk density decreased significantly (P<0.05). According to results of this research, adding hydrogel into soil cause the haloxylon seedlings to grow and establish successfully in arid and semi arid area. Therefore, in order to reduce the water deficiency problem in conditions similar to this research, application of 0.4% hydrogel together with every 3 days irrigation can be recommended as a successful method for retaining the soil moisture and increasing the growth of haloxylon seedlings. However, in field condition more amounts of super absorbent and different irrigation intervals should be investigated, too.

Determination of copper chemical forms is one of the accurate methods to study the status of this element (Cu) in the soil. Assessment of the relationships between the chemical forms and soil characteristic helps describe the chemical changes of copper in the soil. In this study, 10 surface soil samples (0-30 cm) were collected from different fields in Fars Province with a wide range of physical and chemical properties. A after preparing soils, various chemical forms of copper in soil were measured by sequential extraction method. Chemical forms of copper in the soil were in the following order: CuEx=CuMnO= ND < CuCa=5% < CuAFe =6% < CuOM=13%< CuCFe=28% < CuRe=48%. The aerial parts of Soybean plants were harvested for 8 weeks after plant emergence. With measuring the concentration and total uptake of copper in soybean shoots, observed that of above- mentioned forms, organic (CuOM) and carbonate (CuCa) forms,had the strongest correlations with copper in soybean shoots. These forms showed positively significant correlations with Cu concentrations extracted by DTPA and EDTA (P<0.01). The comparison between different chemical forms of copper, indicated that the organic form was positively correlated with the carbonate form. Furthermore, the form connected to the amorphous iron oxides (CuAFe) showed a positive correlation with all of the chemical forms except for organic and carbonate forms.The strongest correlation among the different forms was obtained between amourphous iron oxids and crystaline iron oxides.

In order to investigate the residual effects of continuous many-years application of compost on the amount of lead and cadmium (total and available) in soil and rice plant, an experiment was conducted in split plot based on randomized complete block design with three replications in 2010. Main plot, was application three levels of compost (0, 20 and 40 ton/ha) and also sub plot was effects of 4, 3 and 2 continuous years of without using compost after their use in 2006, 2006 and 2007, 2006-2008 years, respectively. Results showed that, the maximum concentration of available lead (2.58 mg kg-1) and cadmium (0.1 mg kg-1) in soil belonged to 40 ton ha-1 compost treatment. Also, with increasing the levels of applying compost and years of applying of 1 to 3 continuous years, concentration of lead and cadmium (total) in soil increased 85.40 and 58.24 percent compared to control treatment, respectively. Meanwhile, the interaction effect between levels of applying compost and years without applying compost had no significant effect on the amount of lead (available) in soil, shoots and seeds. Also, with continuous 3-year application of 40 ton ha-1 compost after 2 years since the last fertilization, the highest concentration of roots, shoots and seeds with about 3.61, 2.96 and 3 times increase were obtained compared to control treatment, respectively.

K is a nutrient that has a significant role in increasing quantitative and qualitative tobacco yield. The aim of this study is to explore K status and to determine its critical level in the soils of tobacco farms of Golestan and Mazandaran Provinces. 48 soil samples were collected from 0-30 cm depth and 20 samples were selected on the bases contents of clay, OC and K extracted by Ammonium acetate for subsequent studies. The experiment was carried out as a factorial in the form of completely randomized design with three replications in the 20 kg plastic pots. First factor contained 20 tobacco cultivated soils and second factor included two levels of 0 and 150 kg K2O from K2SO4 source. A Healthy similar tobacco seedling, K326 cultivar, was transplanted in each pot. Mature leaves were harvested in 6 cuts during growing period and then their fresh and dry weights were measured. Morphological characteristics such as length and width of leaves, shoot diameter and leaf chlorophyll and chemical properties such as K, sugar and nicotine contents were determined. Fresh leaves were evaluated after processing and finally gross income was also calculated. Results showed that K content significantly affects length and chlorophyll of leaf, fresh and dry matter weights, and nicotine and K contents at α=1% probably level and on shoot diameter and on gross income at α=5% probably level. The critical level of soil K was obtained 240 mg/kg, through graphical Cate and Nelson method on the basis of tobacco relative yield of fresh weight and relative concentration of K using a ratio of 1:20 soil: ammonium acetate (1 N) extractant.

Nuclear approaches are used to determine neighboring and measurement of translocation and nutrients exchange rate between plant and mycorrhizal fungus and selection of effective mycorrhizal strain. Two pot experiments were carried out for determining the effective mycorrhizal fungi strains in alfalfa and barley at Agricultural, Medicinal and Industrial School, Institute of Nuclear Science and Technology, Karaj, Iran. Strains were consisted of G. mosseae, G. intraradices, G. etanicatum and mixed strain (combination of G. mosseae, Giagaspora hartiga and G. fasciculatum) with radioisotope technique. 32P added in the maximum vegetative growth stage to the pots. 32P activity in plant samples were counted by β counter (Multi low level counter FHT770-Eberline Co.). In barley, G. mosseae had more ability of 32P uptake than other strain. These plants had the highest 32P activity of leaf, stem and spike and had higher efficiency in shoot biomass accumulation. Alfalfa- G. mosseae relation were produced the highest shoot dry weight, 32P activity in leaf and stem and specific activity. In general, the strains were different in symbiosis with alfalfa and barley. But, efficiency of G. mosseae in 32P uptake enhanced growth and dry matter production by alfalfa and barley, so G. mosseae can be introduced as an effective strain for both alfalfa and barley.

Mining, manufacturing, and the use of synthetic products (e.g. fertilizer pesticides, industrial waste, and land application of industrial or domestic sludge) can result in heavy metal contamination of urban and agricultural soils. In order to study the heavy metals accumulation in soils, 131 soil and water samples were taken from farmland, non farmlands of 9 regions in Moghan. Soil samples were dried and sieved in lab temperature. Than, after extraction Pb, Cd and Ni were measured using atomozeaition instrument. The results of variance analysis showed that there was significant difference between farm soil and non farm soil sample. All of measured heavy metals in farm soils were more than non farm soils. The accumulation of Pb, Cd and Ni were 3, 20, 5 times as much in farm soils than non farm soils respectively. It is possible, using fertilizers, pesticides and contaminated water could be reasons for this accumulation.