نشریه مدیریت خاک و تولید پایدار
سال دوم شماره 1 (پیاپی 3، بهار و تابستان 1391)

The aim of this research was the study of the effects of soil water conditions, sewage sludge and chemical fertilizers on concentrations of macronutrients and sodium in shoot and root of rice plant (Oryza sativa L. cv. Ali Kazemi) in a loamy sand non-calcareous alkaline soil. The study was performed as a factorial experiment in a randomized complete blocks design including soil water conditions at three levels (continuous submergence, alternate submergence and alternate saturation) and source and amount of organic and chemical fertilizers at 10 levels (control, 100% chemical fertilizers, 20 g sewage sludge/kg of soil with and without 50% chemical fertilizers, 40 g sewage sludge/kg of soil with and without 50% chemical fertilizers, 20 g poultry manure/kg of soil with and without 50% chemical fertilizers and 40 g poultry manure/kg of soil with and without 50% chemical fertilizers) with three replications. The results showed that the effects of soil water conditions and fertilizers on concentrations of macronutrients in shoot and root of rice were significant. Application of 20 and 40 g poultry manure per kg of soil prevented the growth of rice; therefore, these treatments were excluded. The application of 20 and 40 g sewage sludge per kg of soil increased significantly all of macronutrient concentrations except shoot concentration of N and Na and root concentration of K compared to the control and 100% chemical fertilizers. Addition of 50% chemical fertilizers to 20 g sewage sludge per kg of soil increased shoot and root concentrations of P compared to application of only 20 g sewage sludge per kg of soil. Alternate submergence increased shoot and root concentrations of P, K, Ca, Mg and Na (except root concentration of K) compared with continuous submergence and alternate saturation. The concentrations of P, K and Mg in rice shoot were greater than root, while the concentrations of Na and Ca in rice root were greater than shoot.

In order to evaluate the effects of nitrogen and silicon (Si) plus biofertilizers on powdery mildew disease, physiological parameters and yield of wheat (Triticum aestivum L.) cv. N8019, a pot experiment was conducted in a factorial based randomized complete block design at Sari Agricultural Sciences and Natural Resources University during 2009. Treatments included biofertilizer in four levels (non-inoculation, Pseudomonas fluorescens + Bacillus subtilis, Azotobacter brasilense + Azospirillum lipoferum and Azospirillum + Pseudomona + Bacillus), three levels of nitrogen fertilizer (0, 35 and 70 kg nitrogen ha-1) and three levels of potassium silicate (0, 500 and 1000 mg/kg). Results showed that biofertilizers significantly increased both physiological parameters and grain yield of wheat compared to control. Maximum grain yield and leaf area (32.3 and 27.4 percent more than control) were recorded in those plants which received co-inoculation of Azotobacter + Azospirillum (Nitroxin). Furthermore, coinoculation of Pseudomonas with Bacillus (Barvar 2) plus either medium or maximum nitrogen fertilizer markedly improved chlorophyll a and chlorophyll b content. In the case of powdery mildew, the spraying of both 500 and 1000 ppm of silicon significantly reduced the amount of powdery mildew infection and percentage of infected plants compared to control.

In this paper, potential for Cd tolerance, uptake and accumulation by native population of millet (Pennisetum glaucum), lambsquarter (Chenopodium album), flix weed (Descurainia Sophi) and purslane (Portulaca oleracea) in Western Azerbaijan region was studied in a soil spiked with 0, 20, 60 and 100 mg Cd kg-1 soil. The plants were grown in pots containing the contaminated soil. Plants shoots were harvested at the end of their flowering stage. Dry above-ground biomass, Cd concentration in plant shoot, and total Cd removal from soil by plants (MECd) were measured. Results showed that with increasing the soil Cd concentration, shoot biomas of millet and purslane decreased significantly (P≤0.05). However, this reduction, in spite of existance, was not statistically significant for purslane and flix weed. Comparing with other studied plants, lambsquarter and flix weed, with 25% yield reduction in applied range of soil Cd concentrations, were the most tolerant plants to Cd stress. Studied plants did not accumulate high concentrations of Cd, so that, maximum metal concentration in millet, lambsquarter, flix weed, and purslane was about 19, 6, 16, 16 mg kg-1 dry matter, respectively. However, applying lambsquarter and flix weed, would be promising for removal of low levels of Cd from contaminated soils because of producing relatively high biomass and medium metal concentration in plant.

Sorption and desorption of heavy metals by soil solid phase are of crucial role on their behaviour. To assess sorption and desorption of Zn, Cu, Fe, and Mn, four non-acidic and four acidic soil samples were collected from Guilan and West Azerbaijan provinces, respectively. A linear regression procedure was utilized for fitting the linearized forms of the Langmuir and Freundlich isotherm equations to the sorption data. Results showed that for all the studied metals either in non-acidic or acidic soils, the Freundlich equation (R2>0.88) described the sorption data better than the Langmuir equation (R2=0.28-0.90). The amount of sorption parameters for all studied soils was higher in non-acidic soils in comparison with acidic ones. Sorption behaviour of metals differently varied among soils. The highest value for the adsorption maxima was achieved for Fe in both soil types. However, the lowest adsorption maxima were observed for Zn and Mn in acidic and non-acidic soils, respectively. Mean immobilization percent of metals in acidic soils for Mn, Fe, Zn and Cu were 13.2, 11.6, 11.7 and 6.6 percent respectively, and lower than that of non-acidic soils. The lowest and highest immobilization percent for Fe and Mn was observed in soil (5) and soils (3, 4), respectively. Soil (8) showed low Cu and Zn immobilization potential, however soil (4) and soil (1) highly immobilized Cu and Zn, respectively. It is concluded that from an ecological point of view higher sorption potential of studied soils in particular non-acidic soils can be considered in decreasing heavy metals toxicity risks processes.

Nutritional balance is an important factor in improving the yield and quality of horticultural products. In this regard, an assessment of soil fertility, determining optimum fertilizer need and an analysis of nutritional balance in peach orchards are essential. Foliar analysis is a suitable method for evaluating the nutritional status of peach orchards. The method of deviation from optimum percentage (DOP) is a new and easy method compared to the diagnosis and recommendation integrated system (DRIS) method in the interpretation of foliar analysis and its index for individual nutrients is easily calculated. Leaf samples were collected from 61 peach orchards throughout the province during July 2009 and 2010 and analyzed for N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu concentrations. The DOP index was calculated for each of the analyzed elements by applying the following general formula: DOP = [(C × 100)/Cref] - 100, where C is the nutrient concentration in the sample and Cref is the nutrient concentration in the high yielding orchards foliar samples. The indices of DOP were computed for the low yielding orchards. The results showed that the average order of nutrients requirement in these orchards is as following: P>Ca>Mn>K>Fe>Cu>Zn>Mg>N.

Soil saturated hydraulic conductivity is the most important physical properties that has particular importance in identifying, investigating and modeling the water, salts and pollutants transport in the porous medium. Despite numerous research, measuring saturated hydraulic conductivity with direct methods are still costly, time consuming and professional. Therefore estimating saturated hydraulic conductivity with rapid and low cost methods (pedo-transfer functions) with acceptable accuracy is essential. The purpose of this research was to estimate saturated hydraulic conductivity using easily accessible parameters such as particle size distribution, bulk density, total porosity, effective porosity, water content retained at -0.3 and -15 bar matric potentials, %CCE, %OM, pH and EC with Artificial Neural Networks. Saturated hydraulic conductivity was measured from 73 selected points at three depths (10-35, 15-35 and 20-35) with Guelph permeameter and soil samples were taken from same points. Easily accessible parameters were measured in laboratory and preliminary results were obtained. Selected parameters according to sensitivity analysis were sand and clay contents, water content at -0.3 bar matric potential, total porosity and geometric mean diameter of soil particles. Using sensitive parameters, a rapid and low cost method was selected from different designed models. Input parameters were logaritmic geometric mean diameter, total porosity, sand and clay contents with this model.

In order to evaluate the possibility of biological phosphate fertilizers application and compare them with phosphorous chemical fertilizers in corn production, a 3-years field experiment, in the form of Randomized Complete Block Design with 4 treatments and three replications, was conducted in corn fields of Fars Province. The treatments were 1) without phosphorous fertilizer application (control), 2) application of phosphorous based on soil test as microbial phosphate source (Bio fertilizer), 3) application of phosphorous based on soil test as Golden Bio-phosphate source (Bio fertilizer) and 4) application of phosphorous based on soil test as triple super phosphate (chemical fertilizer). Based on soil test, it needs 75 kg.ha-1 P2O5 in every 3 years. Since there was some organic matter, sulfur, and zinc in the organic fertilizers, the calculated amount of these elements was also applied to other treatments. Results of statistical analysis showed that the highest total yield and grain yield, 15000 and 9559 kg per hectare, respectively, obtained from triple superphosphate application but were in a same statical group with microbial phosphate fertilizer. In addition there was a significant difference (P<0.01%) between triple super phosphate and control or Golden Bio-phosphate. In general, the results show that in same conditions firstly corn needs phosphorous fertilizers, secondly application of microbial phosphate source in corn fields is recommended and third using of Golden bio-phosphate source in corn fields is not recommended.

Paddy fields have different status from fertility quality points of view. The quality of fertility and recognition of paddy fields potential are important and necessary with regard to the nutrient elements supply. This study was carried out to survey the spatial variability of soil properties and provide spatial distribution map of characteristics of soil fertility in 306 ha of Rice Research Institute of Iran. Measured soil physical and chemical properties were as follows: clay (C), silt (Si), sand (Sa), pH, Cation Exchange Capacity (CEC), Electrical Conductivity (EC), organic carbon (OC), total nitrogen (N), phosphorous (P) and potassium (K). spatial distribution of the studied properties were evaluated by geostatistics. The results showed that the studied soils inherent characteristics were related to soil fertility, despite the inherent differences in the spatial distribution were in the sufficient level. The available K had stronger spatial structure than other variables which could be an indication of the effect of parent material. Available phosphorous based on variation coefficient had the highest heterogeneity and medium spatial structure which reveals the effect of original and management factors on its behavior. Spatial distribution figure of nutrients shows the heterogeneity in spatial distribution of these elements and it is necessary to avoid uniform consumption of fertilizers in line with site specific nutrient management.

Rock fragments cover is a key factor for soil erosion control, particularly in arid and semiarid environments where vegetation cover is low. The objective of the present research was to study the influence of rock fragment cover on soil erosion and the hydraulic properties of surface flow. The investigation was conducted using a flume with 6 m length, 0.5 m width, and 3% gradient. The treatments included rock fragment cover (0%, 10%, 20%, and 30%), and three levels of flow discharges (3, 6, and 9 lit. min-1). Velocity of water flow decreased 69.2%, the Manning roughness coefficient increased from 0.012 to 0.115, and the Froude number decreased from 2.24 to 0.28 with an increase in rock fragment cover. The Reinhold’s number showed a small variation among different rock fragment covers, but increased with increasing flow discharge. In addition, the rate of soil loss averagely decreased 80.1% in different flow rates with a rise in rock fragment cover from 0 to 30%. Decreasing soil loss rate was related to rock fragment cover by an exponential function.

Effective management of the soil resource requires basic information about the spatial distribution of various soil attributes particularly soil texture. In this study, the ability of two sensors 1) EM38, both horizontal (EM38-h) and vertical (EM38-v) orientations and VERIS3100, both shallow and deep modes to monitor the variation of the soil texture were evaluated and compared at Braunschweig, Germany (www.vti.band.de(. The results showed that EM38 and VERIS3100 readings were directly associated with clay and silt quantities but they were not able to estimate the variation of the clay contents. EM38-v has more ability to predict soil texture in the upper 90 cm in comparison with others methods (R2=0.63). Comparison between present results and the same studies shows that the estimation of the soil texture variation using EM38 and VERIS3100 readings requires more investigation.