Soil science
H. Asgari; M. Barani Motlagh; S.A. Movahedi Naeini; A. Babaei
Abstract
Introduction
Wheat is considered the most important grain and one of the vital food products in Iran. After nitrogen, phosphorus is the most important nutrient required by plants and holds a high priority for the growth, yield and quality of plants. However, due to the introduction of phosphorus in ...
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Introduction
Wheat is considered the most important grain and one of the vital food products in Iran. After nitrogen, phosphorus is the most important nutrient required by plants and holds a high priority for the growth, yield and quality of plants. However, due to the introduction of phosphorus in various reactions in the soil, a small amount of consumed phosphorus fertilizer is removed by the plant and the rest of it is left in a non-absorbable form in the soil. The efficiency of using phosphorus fertilizers and the availability of this nutrient is considered as a limiting factor for the production of agricultural products in calcareous soils with alkaline reaction of Iran. Since graphene and its oxidized form, with large amounts of active oxygen groups and high specific surface area, have been proposed by many studies as non-toxic and biocompatible materials in the production of compounds with improved efficiency of using nutrient, therefore to increase the efficiency of phosphorus consumption in soil, in this study, phosphorus was loaded on graphene oxide (GO-P). The present study aims to assess the influence of this compound as a source of phosphorus and its mixing with triple superphosphate fertilizer (GO-P-TSP) compared to triple superphosphate soluble fertilizer (TSP) on the amount of water retention of fertilizers in soil and phosphorus concentration in aerial parts of wheat plant.
Methods and Materials
Graphene oxide was prepared based on the modified Hamers method. Then graphene oxide was adjusted to certain pH and iron sulfate as a source of iron ions was added to the graphene oxide suspension with vigorous stirring. The mixture was stirred for one hour and then centrifuged for 30 minutes. Then the supernatant was removed and the residue of the compound was dry frozen. In the next step, pH was adjusted with sodium hydroxide (NaOH) solution. Then a certain weight of potassium dihydrogen phosphate salt (KH2PO4) was added to the above suspension. The mixture was stirred for one hour and centrifuged for 30 minutes. After centrifugation, the supernatant was removed and the remains of the phosphorus composition based on graphene oxide were dry frozen. Loading tests were performed in three replicates. pH, EC, bulk density, total concentration of phosphorus and iron and X-ray diffraction spectroscopy (EDS) analysis were measured in the sample of phosphorus composition based on graphene oxide. Then three fertilizer formulations were selected, which included (1) triple superphosphate fertilizer, (2) synthesized phosphorus fertilizer based on graphene oxide, and (3) mixing graphene oxide-phosphorus compound with triple superphosphate fertilizer in a ratio of 50:50% phosphorus.
To investigate the water retention behavior of fertilizers in the soil, dried samples of the three studied fertilizer formulations was added into a sandy soil completely and weighed. At the same time, dried sandy soil without fertilizer was placed in another beaker as a control. Then each beaker was added distilled water and weighed. The beakers were weighed once every three days at room temperature until they reached constant mass. The water-retention behavior of the soil was calculated.
In order to investigate the effect of three fertilizer formulations on phosphorus availability, soil with low amount of phosphorus was selected and physical and chemical properties of the soil sample were measured at a depth of 0-30 cm. A greenhouse experiment on wheat planting was conducted using a randomized complete design with 3 replications. The treatments included three fertilizer formulations at three fertilization levels (10, 15, and 20 mg kg-1) with 3 replications. The control treatment was performed without phosphorus fertilizer. Plants were harvested 72 days after planting, washed with distilled water and dry with tissue paper. The samples were air-dried and then oven dried at 70˚C to a constant weight in a forced air-driven oven. After harvesting, the weight of fresh and dry matter and phosphorus concentration in the soil and aerial parts of the plant were measured. Statistical data were analysed using SAS software (9.4) and the mean values were compared using LSD tests (at 1 and 5% level).
Results and Discussion
The composition of phosphorus based on graphene oxide (GO-P) in powder form had 35.5% of total P2O5, 31.1% of soluble in water P2O5, 19.6 of total iron and 15.28% of total potassium. The result of EDS analysis confirmed the loading of phosphorus on graphene oxide. The pH of the phosphorus composition based on graphene oxide was 5.8, approximately 2.5 units higher than triple superphosphate fertilizer. The bulk density of the compound (GO-P) was significantly lower than triple superphosphate fertilizer. The EC of the compound (GO-P) was similar to the EC of the triple superphosphate fertilizer. Soil water retention with synthesized phosphorus fertilizer based on graphene oxide (GO-P) was higher than soil (control) and other compounds added to soil. Experimental results showed that the addition of prepared fertilizer formulas (GO-P and GO-P-TSP) increased water retention in the soil for a longer period of time, while in the soil without adding fertilizer and triple superphosphate treatment, respectively, from 10 and 11 days, the absorbed water completely evaporated. Therefore, the combination of soil with GO-P and GO-P-TSP compared to the soil without fertilizer and the combination of soil with triple super phosphate (TSP) fertilizer had better water retention behavior. The greenhouse experiment results of wheat planting showed that all treatments were significant (P<0.01). Among all the treatments and measured levels, the control treatment showed the lowest value. The highest concentration of phosphorus in aerial parts of wheat (0.31%) and in soil after harvesting (9.5 mg kg-1), fresh (10.6 g per pot) and dry weight (2.03 g per pot) of aerial wheat plants were related to the treatment of phosphorus compounds based on graphene oxide at the level of 20 mg kg-1.
Conclusion
The highest concentration of phosphorus in aerial parts of wheat was related to the treatment of phosphorus compound based on graphene oxide at the level of 20 mg kg-1. Therefore, with more research in the future to produce "nutritious plants" in sustainable, efficient and flexible agricultural systems, we can benefit from technologies based on carbon materials.
Soil science
K. Asadi; M. Barani Motlagh; S.A. Movahedi Naein; T. Nazari
Abstract
Introduction Methods and MaterialsThis experiment was carried out in a field near the village of Takhshi Mahalle, located 5 km northwest of Gorgan city with geographical coordinates (54° 17´ 56 ʺ N) (52° 51´ 36 ʺ E) in 2022. The physical and chemical properties of the soil ...
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Introduction Methods and MaterialsThis experiment was carried out in a field near the village of Takhshi Mahalle, located 5 km northwest of Gorgan city with geographical coordinates (54° 17´ 56 ʺ N) (52° 51´ 36 ʺ E) in 2022. The physical and chemical properties of the soil were measured at a depth of 0-30 cm in different parts of the farm and the final composite soil was analyzed in the laboratory. Water was measured using conventional methods of sampling and testing water and wastewater. The experiment was conducted as a randomized complete block design with 3 replications. The treatments included control (with distilled water), foliar spraying of iron sulfate micronutrient elements [FeSO4.7H2O (20%Fe)], zinc sulfate [ZnSO4.7H2O (22% Zn)], and iron sulfate + zinc sulfate at a concentration of 5 per thousand at the 4-leaf stage, the 8-leaf stage and both stages (4-leaf and 8-leaf). Foliar spraying was done in the early morning and drip irrigation was used. Plants were harvested 120 days after planting, washed with distilled water and dried with tissue paper. The samples were air-dried and then oven dried at 70˚C to a constant weight in a forced air-driven oven. Iron and zinc concentrations were determined by an atomic absorption device. In order to determine the protein percentage and yield in different treatments, total nitrogen was measured by the Kjeldahl method. The protein percentage and yield were calculated using the following formula: Statistical data were analysed using SAS software (9.4) and the mean values were compared using LSD tests (at 5% level). Results and DiscussionThe obtained results showed that all treatments effects were significant (P<0.01) (fresh forage P<0.05). Among all the treatments and measured traits, the control treatment showed the lowest value. The highest iron concentration with an average of 175.14 mg kg-1 was obtained using iron foliar spraying in both 8 and 4 leaf stages, which increased 22.73 and 34.39% in comparison with only using iron foliar application in 4 and 8 leaf stages, respectively. Zinc foliar spraying at both the 4 and 8 leaf stages resulted in the highest zinc concentration of 71.02 mg kg-1 in forage corn, increasing zinc concentration by 89.86% over the control. In both 4 and 8 leaf stages, an iron and zinc foliar application had the highest chlorophyll index with an average of 57.63. The highest nitrogen content, averaging 2.80%, was observed following foliar spraying of iron and zinc during both the 4 and 8 leaf stages. This represents an increase of 5% and 23.92% compared to iron and zinc foliar application treatments during the respective stages. Consequently, the highest yield and protein percentage were also attained, averaging 310.75 grams per square meter and 17.50%, respectively, with simultaneous foliar application of iron and zinc during both the 4 and 8 leaf stages. ConclusionThe optimal outcomes for measured traits were observed when iron and zinc were concurrently applied at both the 4 and 8 leaf stages. Therefore, it is advisable to administer iron and zinc simultaneously during these growth stages to ensure the attainment of forage with desirable quantitative and qualitative characteristics.
Soil science
E. Mirparizi; M. Barani Motlagh; S.A. Movahedi Naeini; R. Ghorbani Nasrabadi; S. Bakhtiary
Abstract
Introduction: Iron deficiency is one of the most common nutritional problems of plants in arid and semi-arid soils especially in calcareous soils. Iron is essential to many cellular activities, required for optimum growth and development, however it is insoluble in aerated soils at neutral or basic pH, ...
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Introduction: Iron deficiency is one of the most common nutritional problems of plants in arid and semi-arid soils especially in calcareous soils. Iron is essential to many cellular activities, required for optimum growth and development, however it is insoluble in aerated soils at neutral or basic pH, therefore, iron deficiency is common in these soils. The problem is usually solved by using iron synthetic chelates which is a very expensive option. There is, therefore, a need for cheaper and more effective alternatives to traditional Fe fertilizers. Several reports have shown that application of Fe factory by-product to soil tends to raise the availability of Fe and reduce Fe deficiency in plants. Application of organic compounds to soil may improve the solubility of the minerals containing micronutrients and correct their deficiencies in alkaline and calcareous soils. A large amount of slag is produced annually at the Sarcheshmeh Copper Complex, Kerman Province, Iran. So far, the copper slag, however, has not been tested as an Fe fertilizer in calcareous soils. Since about 53.8% of slag obtained from copper concentrate melting is composed of iron oxides, we, thus, examined the effect of copper slag along with organic compounds on the level of upper leaf iron, photosynthetic pigments, SPAD index, the activity of plant enzymes and the level of active iron in the upper leaves of sorghum by performing a factorial experiment in a completely randomized design.Materials and Methods: In order to study the effect of copper slag (one of by-products of melting copper concentrate in Sarcheshmeh Copper Complex, Kerman Province) and organic compounds (cow manure and pistachio skin) on total leaf iron content, photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll), antioxidant enzymes activity (Guiacol Peroxidase, Glutathione peroxidase) and concentration of active iron of young leaves developed of sorghum, a pot experiment was conducted in the greenhouse with three replicates per treatment. We applied experimental treatments including 5 levels of organic matter (pistachio skin, cow manure at 2 and 4 wt. % and control sample), and 11 levels of iron (copper slag, copper slag with sulfur, copper slag with sulfur and thiobacillus, acidic slag (each 2 levels each), sequesterine, foliar application of EDTA, and control sample) to a soil sample with low iron content. At the end of the incubation period, sorghum bicolor was cultured in the above treatments. Ten seeds were sown in each pot. Seedlings were thinned to 4 when they were about 10 cm high. During the growth period, pots were irrigated with distilled water as needed. Before harvesting, SPAD, the concentration of photosynthetic pigments, level of active iron and activity of plant enzymes were also measured in fresh plant samples. Furthermore, the concentration of Fe in the leaves was measured. Analysis of variance was performed using software SAS and significant differences were determined based on LSD (Least Significant Difference Test) at p < 0.05 level.Results and Discussion: The interaction between slag treatments and organic compounds showed that treatments of 4 wt. % of cow manure with slag of 4 times of recommended soil test value (C4S4, and 4 wt. % of cow manure with slag of 4 times of recommended soil test value with sulfur and thiobacillus (C4S4S°T), had significant effects on increasing photosynthetic pigments pigments (chlorophyll a, chlorophyll b, total chlorophyll), SPAD index, activity of plant enzymes (Guiacol peroxidase, Glutathione peroxidase) and active iron. The highest active iron level in the young leaves developed (54.06 mg / kg) was observed in (C4S4S°T) treatment which showed a significant increase compared to the control treatment (17.14). Increased concentration of active iron was also observed due to application of treatments (slag, organic compounds and the interaction between treatments) in sorghum young leaves. The photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll), SPAD index and activity of plant enzymes (Guiacol peroxidase, Glutathione peroxidase) were more correlated with active iron in young leaves developed compared to total iron concentration in these leaves. This indicates that active iron can be used as an index to detect iron deficiency.Conclusion: The higher level of active iron in the young leaves developed was more associated with physiological indices of sorghum as compared with total Fe concentration in these leaves. Therefore, this parameter can be used as an index to detect iron deficiency. In this study, increasing the level of slag consumed and consequently increasing Fe concentration in the leaf resulted in a significant increase in chlorophyll a, chlorophyll b, total chlorophyll, carotenoids and activation of the plant enzymes.
R. Khodadadi; Reza Ghorbani nasrabadi; M. Olamaee; S.A. Movahedi Naini
Abstract
Introduction: Worldwide studies have shown that inappropriate land uses over the past 45 years have resulted in salinization of 6% of the world's land. Salinity has negative effects on soil physicochemical properties and microbial activities. The imbalance in nutrient uptake, ion toxicity and ...
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Introduction: Worldwide studies have shown that inappropriate land uses over the past 45 years have resulted in salinization of 6% of the world's land. Salinity has negative effects on soil physicochemical properties and microbial activities. The imbalance in nutrient uptake, ion toxicity and decreasing water consumption due to high osmotic pressure are resulted from high accumulation of solutes in soil solution. One of the strategies to mitigate soil salinity is the inoculation of crops with different types of beneficial soil bacteria and fungi. Plant growth promoting bacteria (PGPB) are a diverse group of bacteria capable of promoting growth and yield of many crops. The most important growth promoting mechanisms of bacteria are the ability to produce plant hormones, non-symbiotic nitrogen fixation, solubilization of insoluble phosphate and potassium, biocontrol of plants pathogens through producing hydrogen cyanide and siderophore production. Plant inoculation with growth promoting bacteria causes an increase in several indices such as shoot fresh and dry weight, root dry weight and volume as well as chlorophyll content. The synergetic effect of Azotobacter and Azospirillum on the plant has been documented by increasing the absorption of nutrients, production of hormones that stimulate plant growth such as auxin, and influencing the root morphology. Due to the wide area of saline soils, appropriate methods to reduce the negative effects of salinity are of great significance. Given the importance of using bacteria adapted with climatic conditions and soil ecosystems in each region, as well as the efficiency of the combined application of growth promoting bacteria, this study was conducted to investigate the effect of growth promoting bacteria as a single and combined application at two levels of salinity calculated based on the threshold of barley yield reduction (Karoon cultivar) and 50 % reduction in barley yield.
Materials and Methods: In order to record the Azotobacter isolates, 15 soil samples were collected from salt affected lands of Golestan province. Thirty two Azotobacter isolates were isolated by physiological and biochemical tests and cyst production in old culture. Then, their ability to grow in different concentrations of salinity, drought stress tolerance, polysaccharide production, auxin production, phosphorus and potassium solubilization, hydrogen cyanide synthesis and biological fixation of molecular nitrogen were investigated. Based on physiological and growth stimulation tests, Az13 isolate was selected as the superior isolate of Azotobacter for greenhouse test. Azospirillum superior isolate was then prepared from the microbial bank of Soil Science Department, Gorgan University of Agricultural Sciences and Natural Resources. A soil with 16 dS/m salinity was selected to determine the effects of experimental treatments at two threshold salinity levels of yield reduction and 50 % reduction of barley yield. Then, soil salinity was reduced to 8 dS/m (yield reduction threshold) by leaching. After reaching to the desired salinity, the soil was removed from the pots and air dried. The sample was sifted through a 2 - mm sieve and again transferred to the pots. The barley seeds, Karoon cultivar, were used. To prepare the inoculum, firstly the bacterial isolates were grown in the pre-culture nutrient broth medium, and then incubated at 120 rpm in a shaking incubator at 28°C for 48 hours. Afterwards, each seed was inoculated with one milliliter of the bacterial inoculant with a population of 109 CFU/ml. This experiment was conducted as factorial in a completely randomized design with three replications in the greenhouse at Gorgan University of Agricultural Sciences and Natural Resources. The treatments included four levels of bacteria (without inoculation, Azotobacter inoculation, Azospirillum inoculation, combined inoculation of Azotobacter and Azospirillum) and two levels of salinity (8 and 16 dS/m). After 70 days (late vegetative growth period), some growth and physiological indices and concentration of nutrients uptake were measured.
Results and Discussion: The results showed that salinity stress had a significant (p < 0.01) negative effect on growth and physiological traits and nutrient uptake of the plant. The combined application of Azotobacter and Azospirillum bacteria showed a positive significant influence (p < 0.01) on growth, dry weight, and root dry weight in the plant under salinity stress. The combined application of bacteria increased the chlorophyll a, b and a + b content at a salinity level of 16 dS/m by 136.49, 117.86 and 127.97 %, respectively. The combined application of bacteria resulted in a 65.39 and 55.94 % increase in proline amino acid content at salinity levels of 8 and 16 dS/m, respectively. The results revealed that nitrogen, phosphorus and potassium levels increased by 81.97, 80 and 66.67%, respectively, at 16 dS/m salinity level in combined application of both bacteria. Sodium ion accumulation in all bacterial treatments decreased in both salinity levels compared to control treatment and the highest reduction was observed in combined bacterial inoculation. These findings underline the positive effect of bacterial inoculation, particularly their combined application, on the growth and nutrients uptake of barley under salt stress.
Conclusion: Our results indicate that increasing salinity level significantly decreased shoot dry weight, root dry weight, plant height, chlorophyll content and nutrient concentrations of barley. Inoculation of salt-resistant bacteria, including Azotobacter and Azospirillum, reduced the adverse effects of salinity on growth and physiological traits, which was more pronounced in Azotobacter than Azospirillum. The combined application of Azotobacter and Azospirillum had a significant effect on root dry weight, plant height, chlorophyll content, increasing nutrient concentration efficiency (nitrogen, phosphorus, and potassium) and decreased sodium concentration at both salinity levels (8 and 16 dS/m) compared with the individually inoculated bacteria. Hence, the application of Azotobacter and Azospirillum isolates is an appropriate method for pot experiments with saline soils. To apply these results, field experiments in saline soils must be carried out to evaluate the effect of these bacterial isolates on the crop growth, yield and physiological characteristics.
M. Hosseini; S.A.R. Movahedi Naeini; A. Bameri
Abstract
Introduction: The effects of any tillage method on soil properties, depends on location (soil, water and air) and the number of (years) their implementation. Soil compaction reduces yield through increased soil mechanical resistance against root growth and lower water and nutrient use efficiency (Gamda ...
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Introduction: The effects of any tillage method on soil properties, depends on location (soil, water and air) and the number of (years) their implementation. Soil compaction reduces yield through increased soil mechanical resistance against root growth and lower water and nutrient use efficiency (Gamda et al. 18 & Ishagh et al 23). Soil surface and sub surface compaction both reduce yield due to limited root growth and plant potassium uptake (Doulan et al. 14). Sabt et al. (50) reported that in the study area, which the lands are mostly illite clay (high specific surface area) with sufficient nitrogen, soil potassium is the most important limiting factor for the growth of wheat.Considering the point that loess soils in Golestan Province have a high specific surface area,they can provide potassium for plants to produce crop, but for a higher production, potassium fertilizers should be used. Previous studies indicated that production of wheat is limited due to potassium deficiency (4, 49, 54 and 57). In these soils with a high specific surface area, the speed of movement of potassium from the soil solution is low, and doing solimits wheat yield.In loess soils containing high illite and high specific surface area (eg, soilsin the series of Rahmat Abad of Gorgan), ammonium acetate measured potassium on exchange and solution surfaces, which is highly correlated with grain yield (54) . There is a high correlation between grain yield with overload of potassium and Na TPB extraction (57). The aim of this study was to absorb potassium (limiting factor for plant growth) with different tillage systemsat different depths. International recommendations towards reducing the depth and intensity of tillage (from minimum tillage to no-tillage) in order to reduce erosion and oxidation of organic substances plays an important role in determining the amount of greenhouse gases. If potassium absorption does not reduceafter reducing tillage intensity,low or no-tillage methods are preferred. Otherwise no choice but to continue conventional tillage. The second objective is to assess the effects of the treatments (different tillage systems) on the growth and size of the roots and to predict nutrient uptake by plants.
Materials and Methods: This research was a field experiment during 2009-2010 in estates of Gorgan University of Agricultural Sciences and Natural Resources (Seyed Miran Area) with 5 treatments and 4 replications which used completely randomized block design. Treatments were 5 tillage methods including moldboard-ploughing (20-25 cm depth) followed by disking, rotivator (12-17 cm depth), disking (8-10 cm depth), chisel (25- 30 cm depth) and no-tillage. Row spacing, distance between seeds in a rowand the amount of seeding was 20 cm 1.5 cm and 268.5 kg ha respectively (planting was done by hands). The consumption of fertilizers based on soil test results and the results reported by other researchers were added to the soil surface before planting (54). In all treatments, 350 kg per hectare of ammonium phosphate and 200 kg of potassium sulfate before planting and by hands were added. For treated moldboard,rotary cultivator, disc and chisel were used, and for no-tillage system by disc plow and sweep were used.Main parameters measured were soil mechanical resistance at 6 stages during wheat growth using a cone penetrometer (0-8 cm soil depth), soil potassium at two stages during plant growth (before heading and harvest) using sodium tetraphenyl boron(12), ammonium acetate(28) and ammonium nitrate as extractents and using potassium surface excess(8) determination method and also bulk soil solution potassium concentration(2). Yield of wheat and its components were also determined at harvest. Data analysis include the analysis of variance and mean comparisons using LSD and correlations which carried out using SAS software.
Results and Discussion: Results show there was a significant difference between treatments with respect to extractible soil potassium using sodium tetraphenyl boron at 5 percent level and ammonium acetate at 1 percent level, both before wheat heading. Soil potassium content did not differ significantly in this stage when potassium excess method was used. With all methods of soil potassium determination, soil potassium did not differ significantly at harvest. Soil potassium with moldboard-ploughing was less than all other tillage methods at before plant heading. Thomas et al. (55) and Martin Rhoda et al.(40) also stated that soil potassium was greater with no-tillage method. Lopez Phando & Pardo. (34) similarly stated that soil potassium with no-tillage method was greater than moldboard ploughing. According to results of the current experiment, soil mechanical resistance was further reduced as tillage intensity was increased. Soil mechanical resistance with moldboard ploughing was less than other tillage methods between early heading stage and harvest. Lower mechanical resistance with increased tillage intensity increased root growth and soil potassium uptake by wheat grain and straw, leading to greater yield production in accordance with results by Fakori (16).
Conclusions Soil tillage with moldboard ploughing reduced mechanical resistance, increased root density (and possibly soil-root contact surface area) and soil potassium uptake which results a greater wheat head density and yield and also a lower soil potassium with different methods (potassium excess determination and bulk soil solution potassium concentration methods and also using soidium tetraphenyl boron, ammonium acetate extractants) at before heading which is the stage for maximal growth and nutrient accumulation rate. Soil extractants maybe used for plant nutrient uptake and yield predictions in a plant canopy, when plant nutrient uptake has a positive significant correlation with soil potassium and treatments do not affect root growth and the mentioned correlation.
