Iranian Journal of Soil Research
Year:2001 | Volume:15 | Issue:2|Papers Count:19

A completely randomized block design experiment was carried out in 10 provinces in 1997-98 growing season to compare the effects of methods of soil application, foliar application, seed treatment, a combination of soil and foliar application, and a combination of foliar application and seed treatment of a mixture of Fe+Zn+Mn+Cu+B+Mg on the yield and quality of the irrigated wheat crop. Nitrogen, Phosphorous, and potassium were applied at rates based on soil tests and fertilizer recommendations of each region. Sequastrine of iron-138, boric acid and sulfates of zinc, manganese, copper and magnesium at the rates of 10, 20, 40, 30, 20 and 50 Kg/ha were applied to the soil, respectively. In foliar application the same materials were used except for iron which was in sulfate form. The concentration of each salt in the fertilizer Solution was 0.2% and of urea 0.5% giving a total solid concentration of 1.7% In the method of seed treatment, 10 kg seed was mixed in with 1L of a 30% solution of above-mentioned fertilizers. Statistical analysis showed a significant difference at 1% level for grain yield at 5 location and at 5% at another locations in response to different methods of fertilizer application As a whole, the difference in grain yields due to different methods were significant at 5% level for all of the ten provinces. The highest yield from soil application method was obtaind when it was combined with foliar application. Soil application, resulted in the highest yields in 8 out of 11 sites tested. There were no significant differences in the protein content and the 1000 grain weight in different treatments. The different methods, however, caused significant differences the method of soil application for yield increases and foliar application a combination of these two methods will result in improvements for both yield and quality f the irrigated wheat grains.

Chahar Mahal Va Bakhtiari province with 3992 hectares of almond orchards is in the sixth position among other almond producing provinces of Iran. However, severe fruit drop, which reduces the total yield, is the major problem of almond production in this province.This experiment was conducted in order to determine the effects of balanced nutrition on the prevention of almond fruit drop and increasing the yield of 10-year old almond cv. "Mamaei" during 1999-2000, in the Emamieh commercial orchard in Shahre Kord, Iran. Six treatments were arranged in a randomized block design with four replications. Treatments were: T1 - Fertilizer application based on the farmers` conventional method (control); T2 - Localized placement of chemical and organic fertilizer based on Soil and Water Research Institute (SWRI)recommendation; T3 - T2 + foliar application of urea, boric acid and zinc sulfate in the autumn; T4 - T3 + foliar application of urea, boric acid and zinc sulfate in the spring; T5 - T2 + two additional spray of a liquid complete fertilizer and T6 was T2 + foliar application of urea, boric acid and zinc sulfate in the autumn and spring + two additional spray of liquid complete fertilizer.The results revealed that there was a significant difference( at 5% level )between the percentage of final almond fruit formation from the treatments of localized placement of chemical and organic fertilizer compared with the control. At the early growing season, there was no difference in the percentage of initial fruit set among the treatments. However, the highest and lowest final fruit set were observed in the treatments T5 and T1 with 24 and 12 percent, respectively. Fruit drop in 30-days after full bloom was not affected by different treatments except in T3, although fruit drop in 45-days after full bloom decreased significantly (at 5% level) in localized placement of chemical and organic fertilizer treatments when compared with the control. Results demonstrated increase in the yield from 2.260 in the control to 5.860 kg/tree in the localized placement of chemical and organic fertilizer treatments.

Simulation of solute transport in soil profile has many applications in agricultural and environmental problem such as management of plant nutrients, transport of pollutants and reclamation of saline soils. The objective of this study was to compare simulated results from three models with measurements of solute transport in a field planted with corn, wheat and alfalfa. Potassium bromide (300 kg/ha) was applied uniformly to the soil surface and then 1.5 cm of water was sprinkled over the plots in first and second year. Plots were leached 8 times during the first year (each time with 8.5 cm of water) and 9 times in the second year (each time with 10 cm of water). Soli samples were collected from 0-30, 30-60, 60-90 and 90-120 cm depths two days after each application of water. Bromide concentration in soil samples were measured using an ion selective electrode. Moisture content in each plot was also measured using a neutron meter to a depth of 120 cm. Net application of water was based on the calculated evaporation loss from the soil profile. CXTFIT code and three models of Regional Stochastic model (RSM), Convective -Dispersive Equation (CDE) and Transfer Function Model (TFM) were used to simulate leaching of water application under field conditions. The results showed that after addition of 25 cm of water 30% of bromide were leached out from the top 50 cm of soil in all plots in first year and control plots in second year but in second year 47,67 and 70% of bromide were leached out from the top 50 cm of soil in corn, wheat and alfalfa plots, respectively. The RSM, TFM and CDE models showed a reasonable estimates for bromide leaching and storage in soils. In TFM model,the effects of dispersivity is not considered. Thus, the close estimation of RSM and TFM shows that the effect of dispersivity as compared with flow velocity on transport of bromide in soils is insignificant. The differences in simulated results were acceptable, since spatial variations in soil characteristics are unavoidable. Using the simpler TFM model in practical situations and RSM model in research projects is recommended

In a field experiment on a sodic soil in Qazvine province, the effects of different types and amounts of soil amendments were studied using a RCB design with three replicates. The treatments included: chipped wheat straw and manure at rates of 10, 20 and 40 t/ha, gypsum (equivalent to gypsum requirement) cement (5 t/ha), 20 t/ha organic matter with gypsum or with cement (5t/ha), and sulfuric acid equivalent to gypum requirement (applied through irrigation water). Aggregate stability (75-4760µm) and dispersible clay were measured one and four months after application of the amendments. One month after application of treatments, the results showed that application of 40 t/ha straw and 20 t/ha straw with cement or with gypsum increased the MWD significantly, due to increase in the abundance of > 1000 µm and >500 µm aggregates respectively. Applicaion of manure with cement decreased the stability of different size aggregates and MWD, significantly. Also, application of 20 t/ha straw increased MWD due to increase in the abundance of aggregates >500 µm proportional to the decrease in <250 µm aggregates.The abundance of < 250 µm aggregates increased significantly upon the addition of gypsum, sulfuric acid, and manure with gypsum. Four months after addition of the amendments, the MWD increased due to application of different rates of manure, sulfuric acid, cement, gypsum, manure with gypsum, and 40 t/ha straw, mostly due to the increase in the abundance of aggregates greater than 1000 µm. Application of gypsum, at first, increased the abundance of <250 µm aggregates and, later, increased the abundance of >1000 µm aggregates proportional to the decrease in dispersible clay. Although the effects of different amendments on dispersible clay varied, application of gypsum, manure, and straw with gypsum decreased the dispersible clay more significantly than the other treatments. After one month, the amount of dispersible clay decreased from 89.68% in control, to 4.46%, 6.81%, and 7.63%, and after four months from 83.87% in control, to 4.23%, 1.51%, and 4.32%, respectively. Use of sulfuric acid with irrigation water decreased the amount of dispersible clay, one and four months after acid application to, respectively, 52.55% and 19.35%,. The overall results showed the importance of organic matter addition with gypsum for the aggregate formation and stability of a sodic soil due to flocculation of dispersed clay

In addition to the reduction of water availability and toxic ion effects in saline condition, high concentration of Na+ and Cl- ions will normally inhibit the plant nutrition. Suitable application and selection of fertilizer is a management method for enhancing yield and resistance of plants to salinity. To determine the effects of sources and rates of nitrogen on the yield, Cl- and Na+ concentration of wheat a 2-years trial factorial as completely randomized block design in three replications with three levels of N-source and four levels of N-rate was conducted at Nieshabour Agricultural Research Station in 1997-1999. The treatment were as follows:Nitrogen fertilizer from three sources: Urea, Ammonium Sulfate, Ammonium Nitrate.Nitrogen fertilizer at four rates:50%, 75%, 100% , and 125% of the recommended rate.The results showed that Ammonium nitrate significantly increased the grain yield, but the difference between Urea and Ammonium Sulfate was not significant. Also, nitrogen application increased the grain yield significantly. The highest yield was obtained with the treatment 25% higher than the recommended rate ( i.e.230 N kg/ha), and it was 10.2% more than the yield produced in the plots receiving the recommended treatment (184 N kg/ ha). As nitrogen rate increased, Cl- concentration in straw decreased, which was significant(α=0.05) at high levels of nitrogen application.

In order to study the effects of sulfur and compost on increasing nutrients availability of soil, nutrients uptake by wheat, and grain yield, an experiment with was conducted with 3 treatments and 4 replicates, using a complete randomized block design .The experiment was carried out at Gachsaran research station on a soil that was highly calcareous. The three treatments consisted of a control, sulfur application (300 kg/ha), and sulfur (300 kg/ha) + compost (20 ton/ha). Although yield differences were not significant, compared with the control treatment, grain yield increased by 190 kg/ha (3.6%) and 330 kg/ha (8.4%) for, respectively, sulfur and sulfur + compost supplements. Also, the concentration of P, K, Fe, Zn, and Cu in the seeds increased by 5.5,11, 39, 5, and 29% with sulfur supplement, compared with the control. Mn-concentration did not change. At the same time, the increase in the absorption of P, K , Fe, Mn, Zn, and Cu by the seeds were, respectively, 78, 73, 68, 42, 64 and 54 % with sulfur + compost supplements, compared with the control. Results also showed that in the sulfur treatment, the available Mn and K of the soil increased after harvest by 121 and 7%, respectively, but no effect was observed on the concentration of other nutrients. However, sulfur +compost treatment increased avail. P(87%), K(34.5 %), Fe (130%), Zn (490%), and Cu (>100%), compared with the control. But, the amount of increase in avail. Mn was only 63%, which is lower than the 121% increase obtained in the former treatment.

In order to evaluate the effects of micro-nutrient application methods on the yield and quality indices of grape (vitis vinifera), this study was conducted in west Azarbaijan province in 1998- 99. Field experiment was conducted using a randomized complete block design with six treatments and four replications. The treatments were as follows: T1: Control, T2: N and P (farmers conventional method), T3: N, Zn and B spray in winter, T4: foliar spray with micro-nutrient mixed fertilizer, T5: Soil application of all macro and micro-nutrients and T6: a combination of T3, T4, and T5. The highest fruit yield (32.02 kg per vine) was obtained in treatment T4 (α= 0.05). Treatments T4 and T6, increased Zn, Fe and Cu concentration in the leaves opposite to the bunch cluster more than the other treatments. Also, the effect of the treatments on fruit acidity was significant (α= 0.05), with the least amount of fruit acidity in treatment T5.

Apple (Malus domestica L.) is one of the most important horticultural crops in Iran, topping the list of exported fruits on the basis of tonnage. Potassium is one of the essential nutrients with significant roles in apple trees. The competitive effects between potassium and other ions, especially calcium, are very important for this plant. Researchers attribute specific ratios of N/K and K/Ca for the onset of apple fruits quality degradations. Therefore, special care must be given to supplying apples with the needed potassium in terms of amounts and the kinds of fertilizers. An experiment was carried out during the year 2000 in Ziaran of Ghazvin to test different rates of two sources of potassium, namely, potassium sulfate and potassium chloride, combined with micronutrients.The design was a completely randomized block with ten treatments and eight replications. The treatments included the two sources of potassium, each applied at three different rates:(1)recommended rate of Soil and Water Research Institute, (2):50% higher,(3): twice the recommended rate. All treatments , except treament (1) and another teament that received only NPK, received micronutrients. Leaf and fruit chemical analysis and the apple quality aspects showed no differences between the two potassium sources. Increasing the rates of application of either of potassium sources lowered the calcium content of the fruits. The potassium fertilizers combined with micronutrients caused significant increases in vegetative growth, nitrogen, potassium, magnesium, iron and manganese contents, as well as the size and weight of each fruit. The fruits TSS, and sugar and acidity levels of the juice also increased significantly with potassium treatments. However, the juice content of apples from the control plots were, at least, 8% higher than those from the other plots i.e. the juice contents decreased with potassium treatments. Potassium chloride treatments increased the levels of chloride in the leaves and fruits, but no more than the accepted levels. The results showed no differences due to different rates of potassium and from the rates point of view the fertilizer recommendation levels were the best treatments.

This study was carried out in order to determine the effects of balanced nutrition on the yield and fruit quality of 10- year - old almond cv. "Mamaei" during 1999-2000. The experimental site was in the Emamieh commercial orchard in Shahre Kord, with six treatments arranged in a randomized block design with four replications. (see Part One in this issue) The results revealed that there was a significant difference at 5% level between the yield from localized placement of chemical and organic fertilizer treatments compared with the control. The highest and the lowest yields were observed in treatments T6and T1with 5.860 and 2.260 kg/tree, respectively. Results demonstrated a significant increase in fruit size and fruit kernel, weight of 100 fruits and kernels, kernel weight, and kernel protein content in the localized placement of synthetic and organic fertilizer treatments as compared to the control.

Wheat is one of the most important crops in the central province of Iran with many varieties in different agroclimatic zones. Therefore it is important to determine optimum levels of fertilizer use in these different situations. This study provides an economical analysis for the results of an experiment conducted for determining N and P requirement of wheat, cult. Navid.Optimum levels of fertilizer use were determined using a factorial design with complete blocks that contained five levels of N(from urea source) 0, 45 , 90, 135 and 180 (kg/ha), and three levels of P2O5 (from triple super phosphate source) 0,45, 90 (kg/ha), with four replications in cropping years 1991 – 93. Because of the same conditions for all treatments, the effects of other inputs and management have been ignord in this study.Using a quadratic polynomial production function, marginal products of each fertilizer level, maximum possible yield, different combinations of fertilizers to produce a certain amount of yield and profit maximizing levels of fertilizer use are presented and evaluated.

Unsaturated flow in porous media is described by Richards' equation. In order to use this equation, hydraulic conductivity function has to be specified. Brooks - Corey, van Genuchten and van Genuchten- Mualem' s methods have been used for the determination of this function for a Sandy Loam soil in Khuzestan. Undisturbed samples from a top soil were collected in metal cylinders for determination of soil moisture characteristics on sandbox tensiometer and in pressure plate apparatus. RETC program has been used for the derivation of the Van Genuchten's parameters. Results were compared with those obtained from methods suggested by Saxton et al. (1986), Gregson et al. (1987), and Hutson and Cass (1987). Hutson and Cass's model gave comparatively more accurate results. Saxton's model using only soil texture data also produced acceptable regression at high pressure head values.

The portion of soil water that is easily absorbed by plant and usually leads to maximum yield is defined as "Readily Available Water" and is shown as p. This is an important parameter for irrigation scheduling and is useful for determining the irrigation depth (d) and frequency (i). The value of p depends upon the plant species, growth period, rate of evapotranspiration (ETo), and the type of soil.In the present study the value of p is determined for grain corn variety single cross 704 in 2 stages of growth periods in Karaj. The first stage was from seed establishment till appearance of the sixth leaf and the second stage was after appearance of this leaf till soft grain.'This research was carried out with a split plot design in the research station of Seed and Plant Improvement Institute in Karaj for a period of 3 years. The main plots were allocated to the treatments of the first stage and the levels of p fraction in this stage were 0.30 and 0.60. The subplots for the second stage were irrigated when p values were 0.30, 0.50 and 0.70. The amount of p was kept 0.8 for the last growth stage (from soft grain till harvesting). These 6 treatments were replicated 4 times. In this study production potential parameters as grain yield, ear yield dry mater and weight of 1000 grains were determined. Also by measuring the amount of irrigation water, soil moisture balance and evapotranpiration, the water utilization and application efficiency were obtained.Analysis of the results show that by doing short irrigation intervals (p=0.30) during the first stage could be had a good crop establishment and vegetative growth period, then enable us to reduce the number of irrigation (longer irrigation intervals) (p=0.70) in later growth stages. The amount of consumptive use of water in this treatment was 7898 m3ha-1 and grain yield's was 12 ton ha-1.

To investigate the effect of climate and topography on soil genesis and soil forming processes, ten soil profiles from Kheyrudkenar forest located in Nowshar, Mazandaran province, Iran were selected and their genesis, classification. And morphological and mineralogical characteristics were studied along an altitudinal Transect under a very moist and temperate climate and calcareous parent materials. The profiles were selected at 350, 700 and 1050 meters above mean sea level. Forest soils in the study area had Udic moisture regimes and belonged to Mesic and Thermic regimes the forest vegetation was deciduous trees. Parent materials were formed mainly from limestone rocks through dissolution and diverse soils were formed in the region depending on elevation and slope degree and aspect the results indicated that organic matter accumulation, decalcification and clay accumulation are the important processes in evolution of soils used in this study Furthermore, change in elevation and slope aspect affected precipitation and air temperature which in turn were responsible for differences in soil organic matter accumulation and soloum thickness X-ray diffraction analysis shuwed that soil minerals of different pedons vary greatly and that the majority of minerals were inherited from parent materials.