Iranian Journal of Soil Research
Year:2001 | Volume:15 | Issue:1|Papers Count:13

Zinc is one of the essential micronutrients whose deficiency appears in early stages of plant growth. Zinc deficiency has been reported in soils with different characteristics. Soil testing is one of the most popular methods for evaluating nutrients status of soils and fertilizer recommendation and management. For better interpretation of soil testing results, chemical and physical characteristics of soils must be considered.In this study 21 composite surface soil samples were selected from recognized soil representing a variety of soils in Mazandaran province. The clay content in these soils vary from 22 to 57 % , pH from 7 to 7.9, the calcium carbonate equivalent (CCE) from 3 to 39 , organic carbon (QC) from 1.1 to 2.35%, action exchange capacity(CEC) range between 14 to 24 Cmol.Kg-1. Available zinc extracted by DTPA and EDTA- (NH 4)2C03 vary between 0.38 to 1.64 and 0.73 to 2.23 mg.kg-1, respectively. A greenhouse study was conducted as a factorial experiment in a RCBD design with three replications. Sois were treated with two levels (0 and 20 mg.kg-1)of Zn and corn (Zea mays L.) was grown for six weeks.The DTPA and EDTA - (NH4)2CO3 extractable Zn showed a significant positive correlation with plant responses in the third and the sixth week of growth period and results indicated that soil pH and QC improved the correlation between extractable Zn and corn responses. In this study, the critical level for DTPA and EDTA -(NH4)2C03 extractable Zn were 0.80 and 1.20 mgkg-1 , respectively. Based on these critical leves, 50% of Mazandran soils are deficient in Zn.

In arid and semi-arid areas, such as the central parts of Iran, use of proper sources of organic matter is important for increasing soil content of these material. During 1997-98, a field experiment was conducted to investigate the effects of garbage leachate (GL) on soil properties, growth and yield of rice (variety Zayandehrud). The treatments consisted of 0,150, 300 and 600 t ha-1 of GL and a N-P-K-Zn fertilizer treatment in a randomized block design with 3 replications. Rice seedlings were transferred to 4x4 m plots, which were flooded previously. Garbage leachate was applied at tillering and panicle stages. At harvest, straw and paddy yield as well as concentrations of several nutrients and heavy metals were determined in straw and rice grain. Application of 150 and 300 t ha-1of GL increased the straw and paddy yield, but 600 t ha-1GL treatment decreased the yield of paddy as compared to the control. Garbage leachate increased the amounts of available macro- (N, P, K) and micronutrients (Fe, Mn, Zn and Cu) in soil which in turn promoted soil productivity and crop yield. The straw and paddy yields were increased from 7.0 and 4.2 t ha-1 in control to 16.7 and 6.9 t ha-1, respectively, in 300 t ha-1 GL treatment. The amounts of nutrient's uptake was highest in 300 t ha-1 of GL. Application of GL significantly, increased the levels of EDTA-Nickel, Pb and Cr in the soil. Although GL increased concentrations of some heavy metals in rice, particular in 600 t ha-1 GL treatment, the concentrations were below the reported critical levels for these metals.

A completely randomized factorial block experiment was carried out in the spring of 2000 in Sarab, East Azarbyjan to investigate the effect of different levels of phosphorus and zinc on the cadmium content of two potato varieties. The experimental variables included four levels of phosphorus (0, 50, 100, and 150 kg P/ha); four levels of zinc (0, 5, 10, and 15kg Zn/ha); two potato varieties (Agria, and Marphona). Zinc was used in the form of zinc sulfate. The analysis of variance showed significantly different yields (at 1% level) due to the application of zinc. However there were no yield differences in response to the different levels of zinc (Zn15 or Zn10).Likewise there were significant differences (at 1%level) in potato yields due to the application of phosphorus. Like with zinc, there were no differences in the potato yields between the different levels of phosphorus treatment (P0, P50 or P100).Similarly there were different cadmium concentrations in potatoes resulting from the different levels of phosphorus and zinc application (significant at 1% level).The highest cadmium content resulted from 150kg P/ha treatment. However, increasing the level of zinc application resulted in decreased cadmium contents. The interactions between the levels of phosphorus treatment and potato varieties were significant at 5% level. The highest cadmium concentration was found in Marphona potatoes treated with 150kg P/ha. Likewise the interaction between the levels of phosphorus application and the levels of zinc application on the cadmium content of potatoes became significant at 5% level. The highest cadmium concentrations resulted from 150kg P/ha treatments without any zinc application. The interaction between the different levels of phosphorus and the different levels of zinc application on the phosphorus content of the potatoes also became significant at 5% level.Accordingly, the highest phosphorus content in the potatoes resulted from 150kg P/ha without any zinc application.

The grow1h and development of roots play an important role in uptake of nitrogen and other nutrients. Concern about nitrogen pollution of groundwater has stimulated interest in minimizing fertilizer N application and has encouraged research in corn genotypes with high N use efficiency and uptake. This experiment was conducted in 1998 at Tarbiat Moddanes University's farm with corn variety 704. The experimental design was a split plot with randomized complete block design in which 3 plant grow1h stages (8-9 leaves, silking, and black layer formation) were randomized to the main plots and six levels of nitrogen(O,46, 92, 138, 184 and 230 Kg/ha) were in sub plots. The experiment was conducted in 4 replicates. The experimental design for analyzing grain yield data was complete block design. Grain yield was Measured after black layer was formed in grain. Wet and dry weight of root and stem, root length, ratio of root dry matter to stem and root density measured at three plant growth stages. The results showed that different levels of nitrogen fertilizer, plant growth stages and their interactions in all measured traits were significant at 1% level. From three plant growth stages and nitrogen treatments, silking time and N138 had the maximum wet and dry root weight respectively. Mean Root length and density at silking stage were more than other stages. The mentioned traits increased rapidly after planting, but decreased at black layer formation stage. With increasing fertilizer application, root length and density increased, but not linearly Stem fresh weight was more at black layer formation stage than other stages, whereas dry stem weight and ratio of dry root to stem were the highest at silking. The N138 treatment produced the highest wet and dry stem weight Higher or lower applications decreased stem weight Therefore, nitrogen fertilizer can help corn develop deep roots and increase root density at the beginning of the growing season. If nitrogen fertilizer is used in optimum level, the growth of root will be stimulated. Otherwise, root growth will be limited.

A field experiment was conducted at Danial Agro-Industrial Research Field in Khuzestan province, to study the effects of organic matter on some soil physical properties in 1997-1998. The experiment was carried out in randomized complete block design with three treatments and three replications. Treatments were control, 20 and 40 Mg/ha bagasse that were incorporated in 30 cm depth of soil For determining soil physical properties, soil samples were taken from 0-30 cm depth of soil Soil physical properties such as infiltration rate, hydraulic conductivity, bulk density and moisture characteristics curves were determined. Results showed that with application of organic matter, bulk density decreased while hydraulic conductivity and infiltration rate increased Water content at different pressures showed no significant differences between treatments.

Flood water spreading projects have been done with many objectives. One of these objective is increasing soil moisture through the soil profile. When the flood scheme gains water, some part of the water evaporates and some part infiltrates in to the soil. From infiltrated water some part goes to the ground water (depends to residual soil moisture) and the rest remains in the soil profile which gradually evapotranspirates. Soil system is complex and dynamic, that water movement in the soil profile is complex too, therefore investigation on the soil moisture in soil profile is not a simple work. A flood water spreading project was implemented on 1365 hectars in Gareh-Baygon of Fasa in Fars province. From this area 25 hectars are under Eucalyptus trees. In this part (trees) three holes were dug with about 2 meters depths and aluminum tubes were installed. Moisture content in the soil profile was measured with 30 centimeter intervals in every week for 210 days period. A simulation model SWATRE was applied to investigate the soil moisture content in the soil profile. The results showed SWATRE model can be used to investigate soil moisture. Groundwater level in this area was about 17meter from ground surface, the model showed at last 15 cm depth of flood (water) needs to have a flow through 2 meter below the soil surface for the forest area and 10 cm for the other flood schemes.

A. one year (1998) field experiment was conducted to investigate the reclamation and leaching effects of saline barren soil on barely production in Qom province.Arandomized block design with five treatments and 3 replications was used in this study. The treatments were as follows:L0: conventional irrigation practice.L1: two preplanting irrigation.L2: one preplanting irrigation.L3: one extra irrigation after planting.L4: two extra irrigation after planting Changes of soil salinity were measured at two depths, (0-25 and 25-50 cm) prior to planting and 3-4 days after every leaching or irrigation, and after harvesting.Total (grain + straw) and grain yield of barely were determined. Soil salinity decreased by L1 treatment. Electrical Conductivity in surface soil was decreased from 67.1 dS/m to 7.4 dS/m by L1 treatment. Also grain and total yield of this treatment increased significantly compared to the other treatments. Grain yields was increased from 121.3 Kg/ha in the control plot to 2675 Kg/ha, in L1 treatment.

This experiment was conducted for investigation of salt tolerance in alfalfa varieties in green house. Six varieties (Renger , Rehnani , Hamadani . Maopa , Bami and Yazdi ) and six level of salinity (control, -03, -0.6, -0.9. -1.1 and -1.3 Mpa3 ) in a factorial design with four replication were used. In this experiment used pot that fi1!ed with distil1 water tow times. In this experiment green house temperature were about 25±5 cantigrad degree and relative humedity between 70 to 80 percent In water potential -1.1 and -1.3 Mpa all plants were die because salt concentration were excess around the roots. Leaf area affected by water potential and varieties that in the all sampling this effects were significant Effects of varieties on shoot dry matter in all sampling were significant but effect of water potential in three sampeling , vere significant Effect of varieties and water potential were significant on height with decrease in water potential, plant height were decrease too. In those water potential -0.3 , -06 and -09 Mpa, decrease in plant height relation to control were 17.9 .36.8 and 54.7 percent. The effect of variety and water potential on plant water potential were significant. It was concluded that Renger and Rehnani varieties in al1 properties salin condition have superiority relation to other and Maopa variety were sensitive to salinity.

Geostatistics is a branch of applied statistics that provides a wide range of statistical estimators to predict the values of variables at places, where it has not been sampled using neighboring observations. Spatial information can be used to estimate values of properties at unsampled locations through kriging techniques. The variorum is a central tool of geostatistics which is a statistical function quantifying the structure, scale, and intensity of spatial variation. Once it determinesproperly, it can be used not only in the estimation, but also to design and improve the sampling network. Generally, the kriging procedure is optimal in the sense that estimates are not only unbiased but also the estimation variance is a minimum. Several forms of kriging techniques like: ordinary kriging, cokriging, and disjunctive kriging, allow dealing with a wide range of problems in environmental sciences.

Clay minerals with their high surface areas and negative charges are very important for plant nutrition. Qualitative, and semi-quantitative studies as well as structural identification of these minerals could provide good information about adsorption, fixation and release of different cations. In this study, clay mineralogy of five paddy soils in upland, plain, lowland (marsh) and old and recent beach positions were investigated. Sand, silt and clay fractions were separated by centrifuge after the removal of organic matter, carbonates and sesquioxides. For identification of clay minerals, clay suspensions were saturated by Mg and K and then 7 mg of clays were placed on glass slides for XRD analysis. In addition, particles of fine clays were observed by scanning electron microscope (SEM) and analyzed by energy dispersive X-ray analyzer (SEM-EDXRA.). In all of the soils studied, smectite, kaolinite, illite and vermiculite clay minerals were identified. In recent beach position, which was a young landform and lowland under reducing condition, chlorite was identified. But, in the soils developed in upland, plain, and old beach deposits, chlorite was not observed. Clay mineralogy is probably more affected by parent materials and less influenced by aquic and anthraquic conditions. However, there are some. indications that aquic and anthraquic condition may affect quantity of clay minerals, as shown by higher smectite in poorly drained soils. Structural composition of fine clays showed isomorphic substitutions in tetrahedral and octahedra] sheets. XRD results indicated the presence of high charged smectites, which may act like vermiculites in fixing cations such as potassium.