Iranian Journal of Soil and Water Research
Year:2009 | Volume:40 | Issue:2|Papers Count:11

Optimal use of lands heavily relies on careful assessment of agro-ecological resources. This approach is employed to categorize agro-ecologically uniform geographical areas for agricultural developmental planning. Other such interventional modern tools as satellite remote sensing and geographical information system (GIS) have been providing newer dimensions to effective monitoring and management of land resources in an integrated manner for proper agro-ecological characterization. In this paper it is tried to demonstrate incorporation of new tools to extend applicability of Agro-Ecological zoning (AEZ) in Takestan area. Ultimately agro ecological zoning of the region was accomplished through use of collected data as based upon overlaying of climatical zones, as well as on soil and topographical maps. Twenty seven agro ecological zones were finally defined for the study area. Land suitability class and crop yield potential were determined for wheat, barely, maze and alfalfa. The limiting factors were topography ones in the western parts of area and salinity, alkalinity in the eastern parts. The results indicate that number 1 zone benefits from most fertility while the 10th suffers from the least. Based upon a comparison of land use presently in practice with the potential of each zone and a lack of conformity of each application with the potential of land, the importance of land management programming becomes more evident, and is better realized.

Such ion-sink methods as FeO coated strips, (Pi), can adsorb and collect P from soil solution. Ion sink methods function similar to plant-root surface, adsorbing available P ions from the P pool in the soil. The objective of this study was to compare Pi test with Olsen, AB-DTPA, Bray 2 and Mehlich 2 methods to estimate the availability of soil P in alfalfa (Medicago sativa). Available P was detrmined through the above methods in 15 soil samples. Pot experiment was carried out in a randomized block design of two P levels (0 and 200 mg kg-1) plants being harvested in 3 cutting stages. The results indicated that the amount of P extracted through Pi method was significantly correlated with that in other chemical extractant methods. The results obtained from pot experiment revealed that in the first cutting, P uptake was found not to be significantly correlated with P extracted through either Pi or other chemical methods. In the 2th and 3th cutting s P uptake along with other plant indices were significantly correlated with P extracted through Pi method as well as through other chemical methods with Bray2 method being an exception. The results finally demonstrated showed that Pi method can be equally employed for estimating available P in alfalfa plant, as the other chemical methods.

To study the effects of Zabol wastewater treated with two kinds of fertilizer (manure and chemical fertilizer) application vs use of ordinary water on grain yield and yield components in corn (KoSc704) a field experiment was conducted at the University of Zabol, Iran during 2007 growing season. The statistical plan selected was a split plot one of three replications. The treatments were comprised of two kinds of irrigation water (W1=well drawn water, and W2=domestic wastewater) as main plots and five levels of fertilizer (F1=control, F2=manure: 30 tons.ha-1, F3=manure: 15 tons.ha-1, F4=NPK: 350, 200 and 100 kgha-1 and F5=NPK: 175, 100 and 50 kgha-1) as sub plots. Results indicated that irrigation with wastewater significantly increased grain yield of corn as compared with use of ordinary (normal) water. Also it was shown that wastewater had positive significant influence on grain yield and on all yield components with the most effect on 1000-seed weight. Among the fertilizer treatments, F4, in all situations, exerted the most effect on the grain yield and yield components increasing them. Application of wastewater had a significant effect on two osmotic components (proline and carbohydrate) increasing their contents in green leaf tissue. Among the fertilizer treatments, F4 positively affected the contents of these two components the most.

The objective of this study was an evaluation of optimum application rate of PAM for stabilization of unstable soil slopes (hills). Cultivation and cropping on the sloping hills without taking proper and suitable conservative measures causes irreparable damages to agriculture because of soil degradation and the resulting decrease in crop productivity. Experiments were conducted on soil samples taken from unstable sloping marly hills of Sarcham area in Zanjan Province employing a rainfall simulator equipped with an oscillating noze and a small 1×1 meter tilting flume’s tray (adjustable between 0 to 50 percent slope) in Research Institute of Forests and Rangelands of Iran. The treatments were studied at different slopes (15, 20, 25 and 30 %) and rain intensities (25, 50 and 75 mm h-1) to investigate their effect on runoff and on the resulting sediment formation. Results showed that application of different rates of PAM on the steep slopes did not so much affect runoff reduction and/or splash erosion. However applying different levels of PAM did have significant effect on reducing sediment concentration and accumulation. PAM application also increased shear strength of the soil surface due to its improving of aggregate stability. Results obtained from measurements of aggregate stability index and mean weight diameter of soil particles, in various rates of PAM application, showed that use of PAM whit its improving soil physical properties, will reduce soil surface sealing. Some effective parameters in erosion processes in soils treated by PAM were estimated using multivariable linear regression. Since longevity and durability of erosion control through PAM application is short, it is speculated that applications of PAM following major rainfall events may be a successful preventive measure of soil erosion and degradation.

Manganese release kinetics was studied in six composite soil samples by using DTPA as the extracting solution in %35 of saturation moisture and in time range of 0.25-960 hrs. In all the samples, the release of Mn was initially, relatively fast (with 25-55 % of total Mn released during the first 10 hrs), then the rate diminished gradually, approaching zero after a lapse of 720 hrs. Six mathematical equations (zero-order, first-order, second-order, power function, simplified Elovich and parabolic diffusion) were employed to describe and evaluate the kinetics of manganese release. A comparison of the equations, by means of comparing the coefficient of determination (r2) and the standard error of the estimate (SEE) of the equations, indicated that the power function equation best described the kinetics of Mn release, as evidenced by the highest correlation coefficient (r2) along with the lowest value of the standard error of the estimate (SEE).The first-order, second-order, and parabolic diffusion equations, because of their relatively high correlation coefficients and small standard errors, could also be used to describe Mn release kinetics. However, the zero-order and the simplified Elovich equations did not so properly describe manganese release.

Mobility and availability of phosphorus (P) in soils is affected by Phosphorus Sorption Characteristics (PSC). The objective of this research was to study the effect of Poultry Manure (PM) PSC and Standard Phosphorus Requirement (SPR). Ten calcareous soil samples were incubated without and with 1.5% (w/w) PM for 5 months at field capacity at 25±±1oC. The PSC of these samples were determined by using traditional isotherms and single point (1500 mg P kg-1). The results showed that available P increased with an application of PM. Mean available P increased by 58.5%. Sorption data in all the samples were described by Freundlich and linear models. Adsorption isotherm constants decreased with an application of PM. The mean distribution coefficient and Freundlich values of n decreased by 72.4 and 63.6%, respectively. The mean equilibrium buffering capacity (slope of linear model) in treated soils decreased by 12.9%. The mean available P (Y intercept of linear model) and equilibrium P concentration (X intercept of linear model) increased by 34.4 and 132% respectively. The Standard Phosphorus Requirement (SPR) was lower in treated than in untreated soils. The mean P Sorption Index (PSI) decreased in treated soils by 11%. The results in this research revealed that an application of PM may increase the risk of P release into surface water.

Potassium (K) is an element essential for plant growth, playing a significant role in physiological and biochemical processes in plant. The relationship between a soil testing extractant vs. plant nutrient uptake should be a determining parameter in the selection of a soil testing method. The objective of this study was to evaluate different extractants employed for extracting available K in 10 Hamadan soils. The extractants used, were: 0.025 M H2SO4, 0.1 M BaCl2, 0.01 M CaCl2, 1 M NH4OAC, and 1 M NaCl. Potassium uptake and yield by wheat (Triticum aestivum L.), wheat shoots and dry matter content (grown in the greenhouse) were the factors used to assess plant available K. There were significant correlations observed between 0.025 M H2SO4 method with other methods expect for the case of 1 M NH4OAc. There were significant correlations observed between K extracted through different methods and K uptake by wheat shoots. Potassium extracted by 0.025 M H2SO4, 0.1 M BaCl2, and 1 M NaCl showed significant correlations with wheat dry matter yield. The 0.01 M CaCl2, 1 M NaCl, and 0.1 M BaCl2 extraction methods seem to be superior to 0.025 M H2SO4, and 1 M NH4OAC methods in evaluating plant K availability.

Population growth rating, high food demand, and land resource challenges have led to more serious studies of production factors especially the scarce water and soil resources. One of the most basic data items in land resources is the soil map. Therefore, in the process of the present research for preparing soil maps of some soil quality indices at the Faculty of Agriculture Experimental Field (located in the southern part of Karaj city, Tehran) sampling of soil was carried out in 500×500 m grids. Following data normalization, the variograme was developed. For interpolation of soil parameters, Kriging, Cokriging as well as IDW methods were employed. The most appropriate model for interpolation was selected by means of cross validation and error evaluation methods, using RMSE. The results revealed that Cokriging is a more appropriate method than the others for prediction of some such soil properties as Cu, Zn, Mn, Pb, OC and CaCO3 because it was a method developed for limited number of sample cases. As for the rest of soil parameters, IDW was of the lowest number of errors and therefore, was selected as the fittest method for interpolation. Soil characteristic maps were finally prepared, using the most appropriate interpolation methods in GIS environment.

The main purpose of this study was to analyze the problems of Water User Associations (WUAs) in the Irrigation Management Transfer (IMT) process. The study is based upon a descriptive-correlational research method. The statistical population of the study consisted of 2500 farmers in WUAs. A sample of 262 farmers was selected using “Random Sampling” method. Data were collected through questionnaire, the validity (face and content) of which was obtained by a panel of faculty members of the University of Tehran and some experts of the Ministry of Jihade Agriculture. The reliability of the questionnaire was ascertained through Cronbach's Alpha test (a=.721). SPSSWin11.5 Software was used for data analyzing, while factor analysis and correlation coefficient were the methods employed in the research. The results indicated that such problems of: farm area, uncultivated farm area, participation degree and perceptions concerning WUAs' success are of significant relationships. The results of factor analysis indicated that the majority of problems arise from a dissatisfaction with the outcomes, inappropriateness of the project with the project area, lack of confidence in government and lack of support on the part of the government.

Three hundred isolates from rhizosphere of pistachio (Pistacia vera) trees of Kerman province were isolated. Isolates were examined for salinity tolerance at 0, 100, 200, 400 and 600 mM concentration of sodium, calcium and magnesium chloride salts (SAR=13). One hundred and four bacterial isolates were initially selected based on their salinity tolerance and morphological diversities. They were then screened for their Plant Growth Promoting (PGP) characteristics as phosphate solubilization, utilization of ACC as sole nitrogen source, as well as production of siderophore and indoleacetic acid (IAA) -like substances. Eleven isolates with strong tendency for one or more PGPR traits were exposed to stimulated drought stress by adding polyethylene glycol 6, 000 (PEG-6, 000) to the NB medium. The concentrations of PEG were 0, 202.13, 295.75, 428.38 and 548.80 gr PEG/kgNB media, respectively equal of 0, -5, -10, -20 and -30 bar. Of the 300 isolates, more than 80% were able to grow at 600 mM of salinity level. Of the 104 isolates, about 80% showed tendencies for one or more of the PGPR traits tested, 46% were able to produce siderophore, 47% produced IAA, 33% solubilized nonsoluble phosphates, and 22% produced ACC-deaminase. Polyethylene glycol reduced growth significantly (measured as optical density (OD600nm)), but only one isolate at -20 and two isolates at -30 bar were not able to grow. The isolates were morphologically, biochemically and physiologically tested for partial identification.

Accurate water measurement and delivery are basic issues in irrigation networks management and performance. Thus baffle modules have been considered as appropriate means for delivering almost constant discharge within a specific range of upstream water variation. The structure is meant for low discharge delivery and could be employed in farm irrigation. However, the design criteria still needs further improvements. In this paper, the hydraulic sensitivity concept was used to provide two design methods. The results of the first method concurred with that of currently available methods, but it facilitates the design process and provides the designer with comprehensive information concerning the module performance. While the second method improved the structure design and decreased the deviation of the discharge delivery for the given condition of upstream flow variations, notably.