Iranian Journal of Soil Research
Year:2011 | Volume:25 | Issue:1|Papers Count:9

Tissue nutrient status of high yielding plant populations can be a reference norm for evaluation of growth and achievement of optimal yield. Compositional reference norms derived from generic models are important. Yield data of 382 sugar beet fields was analyzed and, using mathematical approach, cumulative variance ratio function[Fic()], and chi-squared distribution function, the low (n1= 259) and high (n2= 123) yielding subpopulations were separated from each other. Cutoff yield was obtained at 53.980 t.ha-1. Critical chi-squared value was found to be 7.3 and was confirmed by using data of leaf samples from 38 fields and Cate-Nelson statistical procedure. Preliminary CND norms of different elements were found as follows: V*N=3.442±0.145, V*P=0.765±0.139,V*K =3.197±0.187, V*Zn=-3.691±0.306, V*Fe=-3.317±0.321, V*Cu=-4.377±0.233, V*B =-3.487±0.293, V*S=1.359±0.283, V*Rd=6.589±0.076. Later, nutrient sufficiency range and critical intervals norms and nutrient indexes for CND were determined using analysis results of 38 sugar beet tissue samples. Satisfactory results were obtained when data of many fertilizer trials were investigated to arrive at preliminary validation of norms and indexes. These norms, indexes, nutrient sufficiency ranges, and critical intervals can be used for prediction of growth, yield, and nutrition disorders of sugar beet.

Phosphorus changes into the Ca-P fractions in calcareous soils. The quantities of these P fractions increase in these soils by P fertilizer application. To determine P fractions in Maragheh area soils under different managements, sequential P extraction method was used. In this study, P uptake, P-use efficiency, and growth differences of various wheat genotypes were investigated by applying four levels of Di-calcium phosphate (0, 80, 160 and 320 mg/kg soil) to ten wheat varieties and genotypes (ََSardari, Sbn/1-64-199, Azar2, Pf82200/Sardari, 5291 Karaj 98-99, Agosta/Safied, Fenkank/15/Safied, Anza/3/Pi//Nar/Hys/Sfied, 87Zhong291, Ghazagestan).  The experiment was conducted in glasshouse conditions using factorial arrangement in completely randomized block design (CRBD), with three replications. The results showed that P fractions in different soil management systems differed significantly. Ca-P fractions were higher in forage-wheat and chickpea-wheat compared to the other treatments of soil management techniques. With higher amounts of Di-calcium phosphate in the soils, shoot and root weight and phosphorus uptake of different wheat varieties and genotypes increased significantly. All genotypes differed significantly in shoot and root weight, P uptake, P shoot and root concentrations, and P-use efficiency by using different quantities of Ca-P fractions. Sardari and Rasad or Fenkang had the highest root weight and, proportionally, higher P concentration in shoot and root compared to the other wheat genotypes. Azar2, Sbn, and Agosta had greater phosphorus use efficiency i.e produced more shoot and leaf for every unit of absorbed P, leading to increased shoot weight. The results suggest that the amount of P fractions differ in different soil management systems. With increasing Ca-P fraction, P uptake and growths of wheat genotypes and varieties increased. It was found that the wheat genotypes with higher root growth/weight absorbed more P and had enhanced P-use efficiency.

Little information is known about nutrient distribution within different parts of spike of wheat, whereas this information is very important for increasing grain yield without negative effect on quality of grain. In this research, the distribution of  two macronutrients (K and Ca) and two micronutrients (Mn and Zn) were investigated during grain filling period in bold and small grains in different parts of spike(P,M,D) in two wheat varieties having large grains (Mahdavi) and small grains (Falat). The research was conducted at the agricultural research farm of College of Agriculture in Islamic Azad University of Saveh during 2007-08 season. Statistical design was split plot and randomized complete block design with three replications. The treatments were three levels of nutrients as the main plot (0, 3 and 4 liter per hectare) and the aforementioned varieties of wheat in the sub plots. Concentrations of the macro- and micronutrients were measured by spectrometer and atomic absorption method, respectively. The results have shown the highest grain weight in the central part of spike as compared to the proximal and distal parts of spike. Number of grains in the central part of spike was more than the two other parts (distal and proximal). There was a positive correlation between grain weight and K, Ca, Mn, and Zn concentration in different parts of the spike. This relation was higher in the central part of spike as compared to the other two parts of spike. Concentration of Zn and Mn decreased during grain filling period. Grain nutrient concentration decreased as distance from the rachis increased. The magnitude of the reduction, however, varied by nutrients. In this study, different varieties did not show any difference in distribution of macro and micro nutrients in rachis as well as rachilla

To study the effect of different vermicomposts, enriched with zinc and iron, on dry weight and seed germination of corn, a pot experiment was conducted in a complete block design with ten treatments and three replications. Nine different vermicomposts including vermicomposted rice hull + chicken manure, rice hull+cow manure, and cow manure and zinc and iron enriched forms of them were used. The nitrogen content of all vermicomposts treatments and the control were equalized by addition of urea. The results of analysis of variance showed that there were significant differences among the treatments with respect to biomass dry weight of corn. The highest dry weight for corn biomass was measured in the treatment having rice hull+chicken manure vermicompost enriched with zinc. In contrast, the lowest dry weight for corn biomass was observed in the control. Different vermoicomposts had significant effects on seed germination of corn. Application of vermicomposts improved seed germination of corn and all treatments had higher seed germination percentages than that of the control. The highest seed germination percentage was observed in the treatment with vermicomposted rice hull + cow manure enriched with iron.

Sustainable afforestation requires maintenance of nutrient elements in soil and stability of soil properties. This study was conducted at the Chamestan Forest and Rangeland Research Station of Iran, starting in 1994. In this completely randomized plan, the oak was planted purely and mixed with four species of Siberian elm, maple, hackberry and hornbeam at 50:50 ratio. 12 characteristics of the soils were tested in two depths to study the probable effects of these plantations on the soil physical and chemical characteristics. Two statistical tests, namely, ANOVA and Duncan were used to compare the different combinations of plantations. The results showed that some planting treatments had caused increase in C:N ratio and decrease in soil CaCO3, absorbable Ca and Mg, and pH compared with the control treatment. Among the pure oak treatment and the mixed treatments, some statistically significant differences were observed such that the pure oak treatment had the minimum amount of total N and the maximum ratio of C:N ratio in the upper layer of soil, while in the lower layer of soil, the pure plantation had the maximum amount of EC compared with the mixed plantations. This study indicates that planted tree species in different types of plantation can affect soil characteristics and, hence, this issue should be considered in forest management.

Waste produced from mushroom production industry, including the mushroom production substrate, has the necessary properties and potentials for use as a soil amendment in agricultural farms. These wastes, known as Spent Mushroom Compost (SMC), are normally disposed of after production process of mushroom. The aim of this research was to study and compare the effects of various SMC's (fresh, one year old, and two years old) at different levels of application (15, 30 and 60 t.ha-1) on the chemical properties of a sandy loam soil. Different SMC treatments were mixed into soil columns and, during a 12-week period in laboratory incubation conditions, they were weekly leached by distilled water. The leachates from the columns were collected at the end of the 1st, 4th, 8th, and the 12th week and analyzed for EC, pH, soluble cations (sodium, potassium, calcium, magnesium) and anions (chloride, bicarbonate, nitrate ). Similar analyses were conducted on the soil samples at the start and at the end of the experiment. The results of leachates and soil samples analyses showed that EC in the two-year-old SMC was the lowest, but the amounts of ‍‍‍calcium and magnesium were the highest. The two- year-old SMC that had higher nitrate content than the other two SMC’s lowered Cl and Na of the soil samples; therefore, it can probably provide some of the nutrient requirement of plants. Comparison of different levels of SMC showed that use of 30 ton ha-1 was more favorable.  The 60 ton ha-1 level caused higher EC and salinity. Considering the high nutrient content of SMC, if this material is used in a suitable amount, it could improve soil chemical properties.

Genetic algorithm is an optimization method for finding the best solution in large design spaces in a way similar to chromosomes and genes in biological systems. In this study, the potential use of classical statistical analysis is compared with genetic algorithm optimization methods for finding the best plant cultivation and the best mixing petroleum-contamination level (1:1 and 3:1, contaminated: uncontaminated soil) for phytoremediation of petroleum-contaminated soil around the Tehran Oil Refinery. Results from the germination and subsequent growth trials showed that, according to the classical statistical analysis method, agropyron, tall fescue, and puccinellia were the optimum plant species for both contamination levels (1:1 and 3:1). In contrast, selection of agropyron, tall fescue, sunflower, and safflower was the optimum solution using the genetic algorithm optimization method. In the phytoremediation experiments, agropyron and contamination level 1:1 were the optimum solutions for achieving successful phytoremediation of the investigated petroleum-contaminated soil using genetic algorithm optimization method. Furthermore, the agropyron-tall fescue combined species and the level 1:1 were the best combined two-plant cultivations and the best mixing petroleum-contamination level, respectively. Therefore, the agropyron-tall fescue combined cultivation and level 1:1 were recommended for phytoremediation of the investigated petroleum-contaminated soil.

In contrast to the efforts made during the last decades to investigate sheet and rill erosion processes in soil, relatively few studies have been focused on quantifying and/or predicting gully erosion. The extension of the use of modern spatial information technologies, such as geographical information systems (GIS), digital elevation modeling (DEM) and remote sensing, have created new possibilities for research in this field. A key issue to be addressed, as the basis for predicting the effects of global changes such as land use and climate changes, is the mapping and quantification of gully erosion rates, including rate of retreat of gully walls and rate of sediment production. This paper presents a method to compute the rate of retreat of gully walls and the associated rate of sediment production caused by gully erosion. The proposed method uses multitemporal aerial photographs and multitemporal digital elevation models, both of which have been processed using GIS techniques. The research was applied to the sub catchment of Hashan with 25 ha area located in Taleghan Watershed. Aerial photographs at scale of 1:20,000 from 1991 and 1:40,000 from 2001 were used to map gully erosion and determine erosion rates between 1991 and 2001. The rates of gully incision and sediment production were computed from the subtraction of multitemporal digital elevation models. The rate of gully walls retreat was 0.202 m year-1. The maximum rate of channel incision (0.5–0.9 m year-1) occurred at the head of the gully and at meandering zones. The rate of sediment production caused by gully erosion was 438±44 ton ha-1 year-1. In comparison with other methods of computing sediment production caused by gully erosion processes, the proposed method integrates the losses due to overland flow, mass movements (collapsing of walls), and gully deepening. In addition, compared with the amount of sediment produced by sheet and rill erosion, this method gives much larger amounts and, supposedly, provides an improvement to locate the areas within the gullies with higher erosional activity.