Soil science
A. Moslehi; M. Feizian
Abstract
IntroductionCadmium (Cd) mobility in soil is affected by various factors and its absorption from soil by tobacco is higher than other crops. Application of phosphate fertilizers in agricultural lands is an essential step to increase the yield of tobacco plants. Since most phosphate fertilizers contain ...
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IntroductionCadmium (Cd) mobility in soil is affected by various factors and its absorption from soil by tobacco is higher than other crops. Application of phosphate fertilizers in agricultural lands is an essential step to increase the yield of tobacco plants. Since most phosphate fertilizers contain small amounts of Cd, the uptake of Cd by tobacco plant in its cultivated areas due to the application of triple superphosphate fertilizer (TSP) is not unexpected. In many tobacco growing areas, the water or soil used is between low and medium salinity in terms of salinity, which can also influence the solubility of cadmium and, consequently, its uptake by tobacco plant. Cadmium can be absorbed through food, drink and respiration. This metal not only is absorbed by the digestive organs, but also is absorbed by the respiratory organs through airborne particles and cigarette smoke. Tobacco is resistant to high concentrations of Cd in soil and can absorb it from Cd-contaminated soil. The aim of this study is to investigate the effect of P fertilizer and salinity on Cd mobility in soil and tobacco plant.Materials and MethodsThis experiment was conducted with the aim of investigating the interaction of three factors of irrigation salinity (0, 20 and 40 mM NaCl), triple tuper phosphate fertilizer (TSP) (0 and 1.5 g kg-1 soil) and soil Cd contamination level (0 and 12 mg kg-1 soil) in a completely randomized design with four replications on shoot Cd concentration, smoke Cd concentration, extraction percentage of DTPA, tobacco ash Cd concentration, Cd mobility factor and Cd fractions in soil. To homogenize the samples, they were thoroughly mixed together and the resulting composite samples were passed through a 2 mm sieve to incubate the samples and then implant. Cadmium contamination levels (0 and 12 mg kg-1) were prepared from Cd(NO3)2.4H2O source. Prior to planting, the relevant levels of contamination were added by spraying on the entire soil surface and mixed thoroughly. Soil samples were transferred to plastic storage containers and incubated for four months in a controlled greenhouse within a temperature range of 25-30 °C and 70% water holding capacity of the soil measured by the weighing method. Cultivation was carried out under controlled conditions in a greenhouse environment located in Bardaskan city. Two 60-day-old tobacco seedlings (Nicotiana tabacum L.) of Cocker 347 cultivar, which were previously seeded in non-contaminated cadmium soil and grown with non-saline water, were transferred to each pot and planted. The cultivar used in this experiment was a greenhouse tobacco cultivar used in the cigarette industry. Immediately after transferring the seedlings to pots, irrigation was performed with saline-free water (distilled water), salinity of 20 or 40 mM NaCl salt for 75 days according to the required treatment. Up to the fourth week, the amount of 400 ml per pot in each irrigation cycle, and after that until the end of the experiment, the amount of 800 ml per pot in each irrigation cycle was applied. Results and DiscussionThe results showed that Cd mobility factor in Cd-contaminated soil increased on average by 25.6%, 32.4% and 36.2% compared to non-contaminated soil at 0, 20 and 40 mM salinity, respectively. Application of phosphate fertilizer significantly reduced the mobility factor of cadmium in non-cadmium-contaminated soils. In Cd-contaminated soil, the extraction percentage of DTPA increased 26.5% and 56.4% with increasing irrigation salinity levels from 0-20 and 0-40, respectively. In non-Cd contaminated soil, TSP application reduced extraction percentage of DTPA 20.2%, 28.4% and 24.6% in 0, 20 and 40 irrigation salinity levels, respectively in compared to non-TSP application. With increasing the levels of soil Cd contamination, the percentage Cd concentration in oxide fraction of soil decreased and the percentage of Cd concentration in carbonate, organic and residual fractions increased. Application of TSP increased the concentration of residual Cd fraction in the soil.ConclusionWith increasing the level of Cd contamination in soil, the percentage of Cd in carbonate and organic fractions increased compared to non-Cd contaminated soil. The results showed that TSP application in Cd contaminated soil in salinitylevels of 0, 20, and 40 mM increased Cd concentration of tobacco ash by 1.47%, 15.89% and 29.80% and increased Cd concentration of tobacco smoke by 23.20%, 23.30% and 18%, respectively. Salinity factor and phosphate fertilizer showed the reverse effect on soluble + exchangeable cadmium and DTPA available Cd in soil, so with increasing salinity, these concentrations increased and with increasing triple superphosphate fertilizer decreased.
H. Sepahvand; M. Feizian; R. Mirzaeitalarposhti; T. Mueller
Abstract
Introduction: Nowadays, because of climate change, there is a great interest in carbon cycle. In most of the soils, the main part of carbon is held as soil organic carbon (SOC) whereas, in soils of the arid and semiarid regions, inorganic carbon, primarily carbonate, is the majority of carbon in the ...
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Introduction: Nowadays, because of climate change, there is a great interest in carbon cycle. In most of the soils, the main part of carbon is held as soil organic carbon (SOC) whereas, in soils of the arid and semiarid regions, inorganic carbon, primarily carbonate, is the majority of carbon in the soils. The major minerals found in the soils of arid regions of Iran are calcite (CaCO3) and dolomite (Ca Mg, CO3) which mainly exist in the soils of the southern and southwestern Iran. Thus, quantifying both SOC and soil inorganic carbon (SIC) is essential to know the way of occurrence of the carbon cycle in the soils. The aim of this study was to compare different methods for the determination of organic carbon in calcareous soils under different land uses of Lorestan province.
Materials and Methods: The study area is located in the Polhoro region of Khorram Abad district, Lorestan Province in western Iran. The sampling area spanned sides of the Polhoro region, which has various land uses, including forest land, cropland, and grassland. Dry and irrigated farming were between cultivated lands. In each land uses, a study plot was chosen. At each sampling point, five subsamples were taken at a depth of 0–30 cm (root zone) and mixed to form a composite sample including one central point and four other points by the distance of 15 m in the four cardinal directions. A total of 40 soil samples were taken across an agroecological region in southwest Iran. The soils had a clay-loam and sandy-clay-loam texture classes and pH above 7. Representative samples were analyzed for SOC and SIC measurements by different procedures. The procedures were included the modified traditional Walkley-Black method (WB) for SOC, Loss-on-Ignition (LOI) Procedure given by Nelson and Sommers (1982) for SOC, and CN analyzer (Vario-EL III) for SOC and SIC. The method presented by Boden, VDLUFA-Verlag, Darmstadt (2016) was chosen for organic carbon and carbonate measurement. This method was used as a reference method to compare results of different methods.
Results and Discussion: In the present study, the soil samples of forest land showed the highest values for TOC and TN, but lowest values for TIC. The measured SOC concentration by WB, LOI and CN analysis methods in the top soil varied among land uses. The highest C concentration (4.52%) was observed in the forest land while the lowest concentration (0.52%) was for dry farming land both by the use LOI method. SOC values varied from 0.8 to 2.3 in modified WB, 0.52 to 4.52 in LOI and 0.93 to 2.72 in CN analysis methods between different land uses. The differences in C concentrations between rangeland, forest, irrigated and dry farming lands were statistically significant and showed the following order for the WB and LOI methods: forest land > irrigated farming > rangeland > dry farming. As expected, C concentrations of LOI and WB were highest in the forest, intermediate in irrigated farming and rangeland and lowest in the dry farming. The relative content of SOCLOI differed significantly across forest and irrigated farming land uses while the difference was not significant in the other two methods. A significant difference also observed in the SOC of forest and irrigated farming with dry and range lands obtained by all three methods. The results of the correlation between the bulk soil and SOC in different methods from the Spearman correlation analysis showed that there was a positive correlation between the TN, TC, clay, and silt of the bulk soil with SOC in the separated methods with the correlation coefficient ranging from 0.1 to 0.92. Conversely, the negative correlation was found between TIC and sand content of the bulk soil with the SOC in the different methods. It can be concluded that calcareous nature of these soils could be one of the reasons for low organic carbon in this research. By comparison between the SOC values measured by WB and LOI methods with CN analysis as a reference method, the WB method showed the results were more near to CN analysis than LOI. The high SOCLOI values for the forest and range land in this research may be related to weight loss from some non-SOM. The results of this study demonstrate that the CN method with combination of dry combustion is a potent method for the accurate estimation of SIC and SOC in calcareous soils. The common approach often involves pretreatment with acid to remove carbonate, which may cause remove organic matter in soil samples and also erosion the instrument. Thus, the combustion method could be a good substitute for acid treatment of soil samples.
Conclusion: Three methods were applied for determinations of SOC concentrations in calcareous soils of Polhoro region and the results were compared. There was a wide range of values in soil properties, but in general, TIC was more than SOC. The results show that the Walkley-Black method with external heating can provide precise estimation for soil organic carbon for these soils. This study illustrates that the WB and LOI technique could be comparable with the CN analysis method and regarded as potent methods to produce accurate results for estimating of organic carbon in arid soils. The results supported the elemental analysis as a precise method to the estimation of SOC and TIC in calcareous soils. Further study is suggested for testing TIC by LOI approach on a wider range of arid and semi-arid soils.
S. Abdi; reza ghasemi; N.A. Karimian; M. Feizian
Abstract
Sum of exchangeable and solution forms of soil potassium is widely used to determine potassium availability for plants. Reliability of these methods is not enough in soils that contain 2:1 phyllosilicates. Additional to exchangeable potassium, nonexchamgeable potassium also has an important role in plant ...
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Sum of exchangeable and solution forms of soil potassium is widely used to determine potassium availability for plants. Reliability of these methods is not enough in soils that contain 2:1 phyllosilicates. Additional to exchangeable potassium, nonexchamgeable potassium also has an important role in plant nutrition. Limited information about availability and release kinetics of nonexchangeable potassium in calcareous soils of Fars province is available. For this purpose, some extractants including ammonium acetate, boiling nitric acid, 0.1M nitric acid, 2M sodium chloride and water were evaluated to prediction of potassium availability for corn in 10 calcareous soils of Fars province. Release kinetics of nonexchangeable potassium was studied using 15 successive 15-min extraction with 0.01M calcium chloride. Kinetics models describing nonexchangeable potassium release rate including zero order, first order, second order, third order, parabolic diffusion, power function and ellovich were evaluated. Results showed that 1M neutral amonium acetate, 0.1M aitric acid, water and 2M sodium chloride extractants had high correlation with corn potassium uptake. Amount of potassium released among studied soils was vary in the range of 243 to 814 mg kg-1. According to R2 and SE, kinetics of nonexchangeable potassium release was described with power function, parabolic diffusion and ellovich equations satisfactorily. According to this fact that constant rate of parabolic diffusion and ellovich models had significant correlations with corn potassium uptake, it is recommended that these two models are suitable for use in these studied soils.
S.K. Mousavi; M. Faizian; A. Ahmadi
Abstract
Abstract
In order to evaluate the effect of different nitrogen application methods on yield and yield components of winter wheat, a field experiment with split plot arrangement in completely randomized blocks design with four replicates was conducted in 2006. Basal dressing in three levels (1- with ...
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Abstract
In order to evaluate the effect of different nitrogen application methods on yield and yield components of winter wheat, a field experiment with split plot arrangement in completely randomized blocks design with four replicates was conducted in 2006. Basal dressing in three levels (1- with no basal dressing, 2- strip and 3- distributing nitrogen fertilizer) as main plot and top dressing in six levels (1- distributing on tillering, 2- two distributing on tillering and before spike appearance, 3- foliar application of fertilizer along with herbicide on tillering and before spike appearance, 4- foliar application of fertilizer on tillering and before spike appearance, 5- two applications: one distributing on tillering and one foliar application before spike appearance and finally, 6- three foliar application of fertilizer on tillering, before spike appearance and milking period) as subplot were carried out. The amount of fertilizer in strip, and all compartmented applications were two thirds of distributing fertilizer method. The highest biomass was recorded in distributing fertilizer (19090 kg ha-1) which was greater 14 and 28 percent in comparison with strip application and no basal dressing, respectively. The highest number of grain per spike belonged to band application of basal nitrogen fertilizer, that was significantly higher than two other treatments. Distributing fertilizer produced the highest grain yield (8525 kg ha-1); however, its differences with strip application was not statistically significant. Top dressing affected grain yield and the greatest yields was observed in one stage distributing, two stage distributing, distributing plus foliar application fertilizing and two stage foliar application fertilizing with herbicide. Grain production in these treatments was statistically greater than two and three stage foliar application of nitrogen fertilizer. The grain protein percent for no basal dressing was significantly lower than broadcasting nitrogen application. The grain protein percent for one stage distributing of top dressing nitrogen fertilizer was significantly higher that other treatments. Based on this research findings, with combined and split application strategies can achieve high yield while saving in nitrogen fertilizer usage.
Keywords: Wheat, Yield, Yield component, Nitrogen fertilizer application methods
