Soil science
Maryam Ghorbani; shahram kiani; Ali Moharrery; Sina Fallah
Abstract
IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change ...
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IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change necessitates providing novel solutions for agricultural production. One of the methods that has gained attention for providing fodder is its production through soilless culture techniques. Maize can be a suitable option for fodder production in soilless culture due to high starch and sugar content, low seed cost, high biomass production, and rapid growth. Proper nutritional management of maize in soilless culture is highly important for increasing the quantity and quality of forage greenery. Little information is available regarding the impact of nitrogen form on the growth, yield and chemical composition of forage plants including maize in soilless culture. This experiment was conducted to investigate the effect of nitrogen form on the chemical composition, leaf photosynthetic pigments concentration and yield of two fodder maize (Zea mays L.) cultivars in soilless culture. Materials and MethodsA factorial experiment based on randomized complete block design was conducted with the two factors of ammonium to nitrate ratio in the nutrient solution (0:100, 12.5:87.5, 25:75, 37.5:62.5 and 50:50) and maize cultivars (i.e., single cross hybrid 704 and single cross 410) and four replications in hydroponic culture at the greenhouse of Shahrekord University. After seed germination and emergence of the first two leaves, the maize seedlings were transferred to 10-liter plastic pots containing perlite (0.5-5 mm) and were manually fertigated with different ammonium to nitrate ratios on a daily basis. Before harvesting, chlorophyll a, b and (a+b), and carotenoids were quantified in leaves of plants. At the end of the tasseling stage, the plants were harvested. After harvesting, the root, stem, and leaf parts were separated, and the fresh weights of the samples were measured. Plant samples were dried in an oven at 60 °C. Then, dry weights of samples were measured and samples (root and leaf + stem) were ground for nutrient analysis including of N, P and K. Analysis of variance was performed using SAS software version 9.4. Means comparison was conducted using Duncan's multi-range test at p <0.05. Results and DiscussionThe results showed that in single-cross hybrid 704 and single-cross 410 cultivars, respectively, increasing the applied ammonium to 37.5% and 50% in the nutrient solution caused a significant increase in the shoot nitrogen concentration. Application of ammonium in the nutrient solution led to an increase in shoot and root phosphorus concentration in both maize cultivars compared to the nutrient solution without ammonium. The highest concentration of phosphorus in shoot (18.02 g.kg-1) was observed in the single-cross hybrid 704 cultivar when maize plants fed with a nutrient solution containing 50 percent ammonium, which was 3.2 times higher than the shoot phosphorus concentration in plants fed with nutrient solution without ammonium. Furthermore, at the 50:50 ammonium to nitrate ratio in the nutrient solution, the lowest root potassium concentration was recorded in both maize cultivars. In single-cross hybrid 704 cultivar, application of nutrient solution with ammonium to nitrate ratio of 50:50 resulted in a significant 31% decrease in leaf chlorophyll a concentration compared to plants fed with a nutrient solution containing 25% ammonium (with the highest chlorophyll content). The leaf chlorophyll a concentration in single-cross 410 cultivar showed an increasing trend with increasing ammonium in the nutrient solution up to 25 percent, and then a decreasing trend with further increase in the ammonium proportion. Moreover, a 31.4% significant decrease in chlorophyll b concentration was observed in plants fed with a 50:50 ammonium to nitrate ratio compared to plants fed with a 37.5: 62.5 ammonium to nitrate ratio. The highest leaf carotenoid concentration was recorded in single-cross hybrid 704 cultivar and at 25:75 ammonium to nitrate ratio, which was 1.4 times higher than the leaf carotenoid concentration compared to plants fed with nutrient solution without ammonium. The highest relative leaf moisture content was observed in the plants nourished with ammonium to nitrate ratio of 25:75, which showed a significant 20% increase compared to the ammonium-free nutrient solution. The results also indicated that the application of 50% of nitrogen in the form of ammonium in the nutrient solution led to a significant decrease in the leaf surface area of maize. The highest shoot and root fresh weights were obtained in the plants nourished with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. The results showed that the highest water (solution) use efficiency based on fresh weight was recorded in plants fed with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. ConclusionBased on the results of the present study, the highest shoot and root fresh weights of both maize cultivars were obtained in plants fed with 25:75 ammonium to nitrate ratio. Given the limitations of water resources and rainfall, optimal use of minimum water to produce maximum agricultural crops must be cnsidered. According to the results of this research, application of nutrient solution with ammonium to nitrate ratio of 50:50 led to ammonium toxicity and a reduction in forage yield in both maize cultivars. Therefore, replacing 25% nitrate in the nutrient solution with ammonium and selecting the single-cross hybrid 704 cultivar (due to higher yield compared to single cross 410 cultivar) is recommended to achieve maximum fodder yield in soilless culture under conditions similar to this study.
Soil science
S. Naseri; Sh. Kiani; H.R. Motaghian
Abstract
IntroductionUrea is one of the nitrogen chemical fertilizers for vegetable production in soil. But it is seldom used in soilless cultures. Leafy vegetables such as Lettuce (Lactuca sativa L.) contain high levels of nitrate and attempts have been made to reduce the nitrate concentration in this crop for ...
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IntroductionUrea is one of the nitrogen chemical fertilizers for vegetable production in soil. But it is seldom used in soilless cultures. Leafy vegetables such as Lettuce (Lactuca sativa L.) contain high levels of nitrate and attempts have been made to reduce the nitrate concentration in this crop for human consumption. Using reduced forms of nitrogen, i.e. urea, is one of the applied strategies for reducing nitrate accumulation in lettuce. Little information is available concerning urea as a source of nitrogen for production of leafy vegetables such as lettuce in soilless culture. This experiment was conducted to investigate the effect of different ratios of urea:nitrate in nutrient solution on the growth indices, yield and nitrate accumulation of red French lettuce (Lactuca sativa L. cv. Lolla Rossa) in soilless culture. Materials and MethodsA hydroponic experiment using completely randomized design was carried out with seven ratios of urea:nitrate in nutrient solution and four replications in the research greenhouse of Shahrekord University. Urea:nitrate ratios in nutrient solution were: 0:100, 10:90, 20:80, 30:70, 40:60, 50:50 and 60:40. Lettuce seedlings were grown in 2 L plastic pots (one plant per pot) containing mixture of cocopeat + perlite at the ratio of 2:1 (v/v) and were manually fertigated with nutrient solutions on a daily basis. Four weeks after transplanting, lettuce plants were harvested and fresh weights of shoot and root were determined. Plant growth indices including of plant height, plant diameter, leaf length, leaf width, leaf number, leaf greenness index and leaf brix level were measured. After measuring the growth indices, the leaves were grouped separately according to leaf numbers 1-10=outer leaves, >11= inner leaves. The samples were dried in an oven at 60 °C and were ground. Nitrate concentrations in samples were determined calorimetrically using a spectrophotometer at a wavelength of 410 nm. Analysis of variance was performed using SAS software version 9.4. Means comparison was conducted using least significant difference test at 0.05 probability level. Results and DiscussionThe results indicated that application of different ratios of urea to nitrate in nutrient solution had not significant effect on the lettuce growth indices including of plant diameter, leaf length, leaf width, leaf number, leaf greenness index and leaf brix level in comparison with 0:100 of urea:nitrate ratio. Also, root and shoot fresh weights were not affected by urea:nitrate ratio in nutrient solution. The greatest quantity of shoot fresh weight (141 g per plant) was obtained with a 50:50 urea:nitrate ratio. However, this was not significantly different from the shoot fresh weight (125 g per plant) observed when urea was not included in the nutrient solution. Shoot nitrogen concentration (except for plants nourished with a 50:50 urea:nitrate ratio) was not affected by increasing the urea:nitrate ratio in the nutrient solution. The results revealed that application of urea in nutrient solution effectively provided the nitrogen requirement of lettuce. This indicates that lettuce plants can efficiently hydrolyze urea and use it efficiently as a nitrogen source. Application of urea in the nutrient solution led to significant decrease in the nitrate concentration of lettuce root (P< 0.05). Moreover, increasing urea:nitrate ratio in nutrient solution resulted in significant decrease of the nitrate concentration of outer leaves, inner leaves and all leaves of lettuce (P< 0.01). The highest and lowest nitrate concentration in inner, outer and all leaves of lettuce were obtained in plants nourished with 0:100 and 50:50 urea:nitrate ratio in nutrient solution, respectively. Application of urea:nitrate ratio of 50:50 led to the meaningful decrease of nitrate concentration in root (43%), outer leaves (41%), inner leaves (44%) and all leaves (43%) of lettuce in comparison with 0:100 of urea:nitrate ratio. Urea had a repressive effect on nitrate influx and decreased its uptake by plants. Also, after urea uptake by plant root, it is first degraded by cytosolic ureases and then ammonium is incorporated via the GS-GOGAT (Glutamine Synthetase- Glutamine α-OxoGlutarate Amino Transferaze) cycle. Therefore, application of urea in nutrient solution can lead to the reduction of nitrate accumulation in plants. ConclusionBased on the shoot fresh weight and nitrate concentration in lettuce leaves, replacing 50% of nitrate in nutrient solution with urea is recommended for red French lettuce production in hydroponic culture under the conditions of the present study. Compared to other nitrogen fertilizers, urea has a lower price and its application in nutrient solution is useful in reducing production costs.
Soil science
N. Lotfi; Sh. Kiani; H.R. Motaghian
Abstract
Introduction
Selenium (Se) is one of the beneficial elements for plants, which is usually not supplied in the nutrient solutions used in soilless cultures. It is an essential element for both humans and animals. Application of Se at low concentrations has a positive effect on the growth and quality ...
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Introduction
Selenium (Se) is one of the beneficial elements for plants, which is usually not supplied in the nutrient solutions used in soilless cultures. It is an essential element for both humans and animals. Application of Se at low concentrations has a positive effect on the growth and quality indices of plants. Nitrate accumulation in leafy vegetables poses threaten to human health. Leafy vegetables such as lettuce (Lactuca sativa L.) contain high levels of nitrate. According to the results of some researches, application of Se in the nutrient solutions can decrease nitrate accumulation in vegetables. However, the optimum concentration of Se in the nutrient solution for lettuce production in hydroponic culture is still not clear. This experiment was conducted to elucidate the effect of different levels of Se in the nutrient solution on the growth indices, yield, and nitrate accumulation of red French lettuce (cv. Lolla Rossa) in soilless culture.
Materials and Methods
A perlite culture experiment, using completely randomized design, was carried out with seven levels of Se in the nutrient solution (0, 0.1, 0.5, 1, 5, 10 and 20 µmol L-1) with four replications in the research greenhouse of Shahrekord University. Lettuce seedlings were grown in 1.7 L plastic pots (one plant per pot) containing perlite with size of 0.5-5 mm and were manually fertigated with the nutrient solutions on a daily basis. Different concentrations of Se were applied as sodium selenate (Na2SeO4.2H2O) in the nutrient solution (Domingues et al., pH= 5.4±0.1, EC=1.36-1.41dS m–1). After four weeks, lettuce plants were harvested and the fresh weights of shoots and roots were measured. Plant growth indices consisting of leaf number, leaf length, leaf width, plant height, plant diameter, leaf chlorophyll index, and leaf total soluble solids were determined. In one bush in each treatment, the leaves were separated as 1st to 10th outer leaves and other inner leaves. The leaves were dried in an oven at 70 °C and were ground. Nitrate concentrations in outer and inner leaves were measured calorimetrically using a spectrophotometer at a wavelength of 410 nm. Shoots Se concentration was determined with ICP-MS after wet digestion of samples with HNO3 and H2O2. Analysis of variance was done using SAS software and means comparison was conducted using the least significant difference test at 0.05 probability level.
Results and Discussion
The results indicated that application of Se in the nutrient solution had not significant effect on the lettuce growth indices including of leaf length, leaf width and leaf number. Application of 10 µmol L-1 of Se in the nutrient solution led to significant decrease of plant height in comparison with control, but plant diameter increased with application of Se in the nutrient solution. The highest plant diameter was observed in 10 μmol L–1 of Se treatment. The highest and the lowest shoot fresh weight were obtained under 0 and 1 μmol L–1 of Se in the nutrient solution, respectively. Application of 1 μmol L–1 Se increased shoots fresh weight by 22% comparing to the control. Shoot Se concentration was increased with application of Se in the nutrient solution. The highest concentration of Se in shoots (15 mg kg-1 dry matter) was observed at the rate of 20 μmol L–1 of Se in the nutrient solution. The amount of Se accumulated in the plant tissue is important in biofortification programs. The results showed that application of Se in the nutrient solution (with the exception of 1 µmol L-1 of Se) led to significant decrease in the nitrate concentration of roots, outer leaves, inner leaves and all leaves of lettuce. The lowest nitrate concentration in all leaves of lettuce (2095 mg kg-1 fresh weight) was obtained in plants nourished with 0.5 μmol L–1 of Se in the nutrient solution. Compared with control (0 μmol L–1 of Se), nitrate concentration in all leaves for 0.5 μmol L–1 of Se treatment was decreased 28%. Selenium has a positive function on decreasing nitrate accumulation in plants via regulating the transport of nitrate and enhancing activities of nitrogen metabolism enzymes.
Conclusion
According to our results, application of Se decreased nitrate concentration in lettuce plants. Therefore, application of Se in the nutrient solution at the rate of 0.5 μmol L–1 is suggested for red French lettuce production in hydroponic culture under the conditions of the present study.
Soil science
M. Gheitasi; Sh. Kiani; A. Hosseinpur
Abstract
Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification ...
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Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification inhibitors (NI) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in soil. In different studies, the positive effects of these compounds on the reduction of N losses from soil and increase of N use efficiency and crop yield have been demonstrated. The 3,4-dimethylpyrazole phosphate (DMPP) is a very popular nitrification inhibitor around the world. The efficacy of this molecule depends on climatic conditions and soil properties including of texture, pH, organic matter, moisture, temperature and mineral nitrogen. In this experiment, the effects of NI 3, 4-dimethylpyrazole phosphate on the N use efficiency of two spinach varieties were investigated in different soils.
Materials and Methods: A pot experiment was conducted in a completely randomized design with a factorial arrangement with three replications at Shahrekord University. Experimental factors were different N fertilizer sources, soil types and spinach varieties. Three N fertilizer sources consisted of urea, ammonium sulfate nitrate (ASN) and ASN plus DMPP (0.8 %). A no added N fertilizer treatment was considered as the control. The soil factor contained three different soils with different physical and chemical characteristics. The textures of the soils No. 1, 2 and 3 were loamy sand, loam and silty clay, respectively. Three selected soils were non-saline (EC1:2=0.14-0.31 dS m-1) and alkaline (pH1:2=7.9-8.0). Organic carbon and calcium carbonate equivalent (CCE) ranged from 0.26 to 0.35%, and 28.5 to 36.2%, respectively. Two spinach varieties were smooth-leaf (Giant Santos) and wrinkled-leaf (Viking). The used soils were mixed homogenously with 100 mg P kg−1 soil as triple super phosphate, 5 mg Fe kg−1 soil as Fe-EDDHA, 15 mg Zn kg−1 soil as ZnSO4.7H2O, 5 mg Mn kg−1 soil as MnSO4.H2O and 2.5 mg Cu kg−1 soil as CuSO4.5H2O. Nitrogen was applied at the rate of 150 mg kg-1 soil in two split doses before sowing and after one month. Twelve seeds were sown in 7 kg soil in plastic pots, and then placed in a greenhouse. The pots were thinned to 7 seedlings per pot after plant establishment. One week before harvesting, 10 measurements were done using a chlorophyll content meter to determine chlorophyll content index of leaves. At the end of the experiment, shoot dry weight was determined and plants were mixed and dried to measure N concentration. Finally, shoot N uptake and N use efficiency were calculated in different treatments.
Results and Discussion: In the present study, spinach plants fertilized with ASN+DMPP had a better appearance (dark green color) than those grown without DMPP. The results indicated that application of ASN with DMPP led to significant increase of leaf chlorophyll content index in comparison of ASN and urea fertilizers in all studied soils. Application of DMPP slowed down the process of ammonium oxidation to nitrite. Thus, this increase may be due to the role of ammonium in N nutrition of spinach plants treated with DMPP. This may be explained by the fact that ammonium has a positive effect on the synthesis of polyamines, cytokinins and gibberellins. The presence of these two phytohormones retarded senescence and chlorophyll degradation in plants. However, adding ASN to DMPP resulted in a significant decrease of shoot dry weight as compared with the ASN and urea fertilizers in soils No. 1 (loamy sand) and 2 (loam). In soil No. 3, shoot dry weight was not affected in plants fertilized with ASN+DMPP. Also, agronomic and physiological efficiencies of N significantly decreased by applying ASN+DMPP in comparison with ASN. It seems that application of DMPP strongly delayed the ammonium nitrification to nitrate, and consequently the soil nitrate availability appears not to be synchronized with spinach N needs. Due to short growth cycle of spinach, low availability of nitrate resulted in decreased shoot dry weight of spinach. The highest N use efficiency was observed is soil No. 2 (loam) and Giant Santos had more N use efficiency than Viking.
Conclusion: The results demonstrated that using ASN+DMPP led to yield loss, and we cannot recommend its application as a nitrogen fertilizer for spinach. However, application of ASN+DMPP is an effective strategy for improving qualitative appearance (dark green color) of spinach. Also, all studied indices were not affected in plants fertilized with ASN and urea. Therefore, application of both fertilizers is recommended for spinach production under similar conditions of the present study.
Mahbubeh Gheitasi; Ali Reza Hosseinpur
Abstract
Introduction: Leafy vegetables such as spinach (Spinaciaoleracea L.) contain high levels of nitrate. Using nitrification inhibitors (NIs) such as 3,4-dimethylpyrazole phosphate (DMPP) is one of the strategies for reducing nitrate accumulation. Nitrification inhibitors are compounds that delay the biological ...
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Introduction: Leafy vegetables such as spinach (Spinaciaoleracea L.) contain high levels of nitrate. Using nitrification inhibitors (NIs) such as 3,4-dimethylpyrazole phosphate (DMPP) is one of the strategies for reducing nitrate accumulation. Nitrification inhibitors are compounds that delay the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in soil. Soil properties such as texture, pH, organic matter, moisture, temperature and mineral nitrogen have important effects on the efficiency of NIs to delay nitrification. A pot experiment was conducted to investigate the effects of NI 3,4-dimethylpyrazole phosphate (DMPP) on soil mineral nitrogen (ammonium and nitrate) content, yield and nitrate concentration of spinach.
Materials and Methods: A completely randomized factorial design was carried out employing three factors consisted of nitrogen fertilizer type, soil type and spinach variety with three replications at Shahrekord University. Nitrogen fertilizers included urea, ammonium sulfate nitrate (ASN) and ASN plus DMPP (0.8 %). A no N fertilizer application was considered as control treatment. The soil factor contained 3 different soils with different physical and chemical characteristics. Two spinach varieties were smooth-leaf (Giant Santos) and wrinkled-leaf (Viking). The dose of applied nitrogen in all experimental treatments was 150 mg kg-1 soil that was applied in two split doses before sowing and after one month. The textures of three selected soils were loamy sand, loam and silty clay for the soils number 1, 2 and 3, respectively. Three selected soils were non-saline (EC1:2=0.14-0.31 dS m-1) and alkaline (pH1:2=7.9-8.0). Organic carbon and calcium carbonate equivalent (CCE) ranged from 0.26% to 0.35% and 28.5% to 36.2%, respectively. At 30 and 60 days after sowing, soil subsamples were taken to determine ammonium and nitrate content. The ammonium and nitrate concentrations (extracted with 0.5 M K2SO4) were determined calorimetrically using a spectrophotometer at a wavelength of 667 and 410 nm, respectively. At the end of the experiment, shoot fresh weight was determined and plants was mixed and dried to measure nitrate accumulation.
Results and Discussion: The results indicated that the application of ASN with DMPP led to significant increase of ammonium compared with ASN and urea fertilizers in three soils. At 30 days after sowing, the amount of this increase for ASN plus DMPP in comparison of ASN and urea were 182% and 78% for the soil number 1 (loamy sand), 105% and 65% for the soil number 2 (loam) and 89% and 74% for the soil number 3 (silty clay), respectively. By contrast, the application of ASN with DMPP led to significant decrease of soil nitrate in comparison of ASN and urea fertilizers in three soils. At 60 days after sowing, the amount of this decrease for ASN plus DMPP in comparison of ASN was 52%, 40% and 27% for the soils number of 1, 2 and 3, respectively. It means that the application of DMPP has slowed down the process of ammonium oxidation to nitrite. In fact, the addition of DMPP retained soil nitrogen as ammonium form for longer time. The application of NI DMPP also had positive effect on decrease of nitrate concentration in the soil. Unlike nitrate, ammonium is less susceptible to leaching and thus the application of DMPP can reduces nitrogen loss from the soil. However, the application of ASN with nitrification inhibitor DMPP in soils No. 2 (loamy sand) and No. 3 (loamy) significantly reduced shoot fresh weight of both spinach varieties compared with the similar treatment but without NI. This decrease was due to the toxic effects of high level of soil ammonium on the plant growth. While, in the soil No. 3 (silty clay) in Viking variety, the use of ASN plus DMPP resulted in significant increase of spinach shoot fresh weight to 29% in comparison with the same treatment but without NI. The highest and lowest values of shoot fresh weight (229 and 16.2 g pot-1, respectively) were obtained by Giant Santos variety in soil No. 3 (silty clay) with ASN plus DMPP and soil No. 1 (sandy loam) with no added N fertilizer. The application of ASN with nitrification inhibitor DMPP induced significant decrease of shoot nitrate concentration in spinach in comparison of ASN and urea. The amounts of this decrease for ASN plus DMPP in comparison with ASN and urea were 25.7% and 31.5% for the soil number 1 (loamy sand), 29.1% and 37.1% for the soil number 2 (loam) and 33.9% and 34.0% for the soil number 3 (silty clay), respectively. This decrease was due to ammonium nutrition of spinach plants.
Conclusion: In all studied soils, application of ASN with nitrification inhibitor DMPP is recommended for diminishing nitrate content in both spinach varieties (Giant Santos and Viking).
hamid reza motaghian; alireza hosseinpuor; Shahram Kiani
Abstract
Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release ...
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Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release Kinetics in soils especially in amended soils give information about potential of amended soils to release these elements into solution. Although it is important to study kinetics of micronutrient release from soils to identify soil micronutrients buffering capacity, little attention has been paid to micronutrients desorption rate studies especially in amended soils. The rate of release micronutrients from soil solid phase by considering micronutrients as adsorbed ions or in mineral forms is an important parameter in nutrition of plants by microelements and a dynamic factor that regulates its continuous supply to growing plants; nonetheless, little attention has been paid to micronutrients kinetics inrelease studies.
Material and Methods: In this study, kinetics of zinc (Zn) and copper (Cu) were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w) of manure and vermicompost in a completely randomized design and then amended and un-amended soils were incubated at field capacity, for 30 days. After incubation period, amended and un-amended soils were air-dried and were prepared to kinetics study. Kinetics of Zn and Cu release were studied by successive extraction with DTPA-TEA solution. Two grams of the amended and un-amended soils, in triplicate, suspended in 20 ml DTPA-TEA solution were equilibrated at 25±10C for 1, 8, 24, 48, 72, 96, 120, 144, 168, 336 and 504 h by shaking for 15 min. before incubation and 15 min. before the suspensions were centrifuged. Seven drops of toluene were added to each 1000 ml of extractant to inhibit microbial activity. Zinc and copper desorption with time was fitted by using different equations (Zero-order, First-order, Parabolic diffusion, Simplified Elovich, and Power function).
Results and Discussion: Results showed that released Zn in soils amended with manure and vermicompost compared to control soil significantly increased (p0.05) and released Cu in soil amended with vermicompost decreased significantly (p
roza kazemi; shahram kiani
Abstract
Introduction: Nitrification inhibitors (NIs) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in the soil. Many popular NIs such as nitrapyrine (NP), dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) are produced ...
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Introduction: Nitrification inhibitors (NIs) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in the soil. Many popular NIs such as nitrapyrine (NP), dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) are produced and used in agricultural soils. Dicyandiamide is a very popular NI in some of the world countries. It delays nitrification process in the soil through its bacterial static property. It is easy to blend with commercial fertilizers such as urea, due to its low volatile nature. Application of urea in combination with nitrification inhibitor DCD lengthens nitrogen presence in soil as ammonium form. It has several beneficial effects for agriculture and enhances environmental protection. Studying the ammonium oxidation kinetics in the presence of nitrification inhibitor DCD can provide the experts in agriculture with very useful information regarding the ammoniumdurability in different soils. This research has been done to study the effect of using NI dicyandiamide on the kinetics of ammoniumloss in some calcareous soils of Chaharmahal Va Bakhtiari province, Iran.
Materials and Methods: This research was conducted as factorial using completely randomized design with two factors of nitrogen fertilizer type and soil type with three replications at laboratory conditions. In this experiment, nitrogen fertilizer type included 2 levels of: 1- urea 2- urea plus nitrification inhibitor DCD (3.2%). A no added nitrogen fertilizer was considered as control treatment.The soil factor also consisted of 5different soils with a wide variation in soil physical and chemical characteristics. Five selected soils were non-saline (EC1:2=0.14-0.76 dS m-1) and alkaline (pH1:2=7.5-8.2). Organic carbon and cation exchange capacity (CEC) ranged from 0.48 to 2.34% and 10 to 30 cmolc kg-1, respectively. The dose of applied nitrogen in all experimental treatments was 50 mg kg-1 N as urea. Forty-five containers containing different soils were incubated at 20°C for 105 days. At 1, 7, 14, 21, 28, 35, 49, 63, 77, 91 and 105 days after adding urea and urea+DCD, soil subsamples were extracted to determine ammonium content. The ammonium concentration (extracted with 0.5 M K2SO4) was determined colourimetrically using a spectrophotometer at a wavelength of 667 nm. Then zero, first and second order equations were calibrated on the residual ammonium in the soil using SAS 8.02 and the best equation was seleted on the basis of coefficients of determination (R2) and standard error of the estimate (SE). In addition, ammonium half-time and nitrification inhibitor index were calculated.
Results and Discussion: The results indicated that the first order equation was able to describe ammonium oxidation kinetics of the soil in all of the experimental treatments (control, urea and urea+DCD). The average values of R2 and SE of first order equationwere 0.915 and 1.51 in control, 0.903 and 4.98 in urea treatment and 0.863 and 4.92 in urea+DCD treatment, respectively. It means that ammonium oxidation kinetics is dependent on the ammonium concentration in soil. In all study soils, the slope of the first order equation in the urea treatment with DCD has been less in comparison to similar treatment but without NI. This may be explained by the fact that application of DCD has slowed down the process of ammonium oxidation to nitrite. The application of urea with DCD resulted in increase of ammonium half-life (calculated with first order equation) in the soil comparing to urea fertilizer without NI in all of the studied soils. The amount of this increase for DCD was 34.8, 31.6, 31.1, 25.1 and 40.4 days for the soils number of 1 2, 3, 4, and 5, respectively. Increasing the presence of ammonium in soil can be considerable for agricultural and environmental purposes. The maximum nitrification inhibitor indexes were 11.3% and 28.1% after 28 days of incubation in soils number 1 and 3, respectively. These nitrification inhibitor index values are in agreement with observations by other researchers.
Conclusion: The results showed that nitrification inhibitor DCD is compound with a high capacity for extending ammonium presence in studying soils under conditions of this experiment. However, its efficiency was dependent to physical and chemical properties of soil.According to the results, first order equation was the best equation for describing ammonium oxidation kinetics in tested soils fertilized with urea and urea+DCD.
A. Taheripur; Sh. kiani; A. Hosseinpur
Abstract
Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. ...
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Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. Phytoextraction is one of the most popular and useful phytoremediation techniques for removal of heavy metals from polluted soils. For chemically-assisted phytoextraction, different chelating agents such as EDTA and citric acid are applied to soil to increase the availability of heavy metals in soil for uptake by plants. A pot experiment was conducted to elucidate the performance of chelating agents addition in improving phytoextraction of Cu and zinc Zn from a naturally contaminated soil by maize (Zea mays L.) cultivars.
Materials and Methods: A factorial experiment in a completely randomized design was carried out bythree factors of chelate type, chelate concentrations and maize cultivars with three replications in 2012 at ShahreKord University. Chelating agents were Ethylene Diamine Tetra Acetic Acid (EDTA) and citric acid (CA). They were applied in concentration levels of 0, 0.75 and 1.5 mmole kg-1 soil with irrigation water. The three maize cultivars used were single cross 704 (SC-704), three v cross 647 (TVC-647), and single cross 677 (SC-677). The pots were 23 cm in diameter and 23 cm deep, and were filled with 4 kg of a silty loam, calcareous soil taken from the surface layer of Sarcheshmeh copper mine area. Maize plant s was grown under greenhouse conditions over 90 days. After the harvest, soil available Cu and Zn contents (extracted with DTPA-TEA) were determined by atomic absorption spectrophotometry (AAS). Plant samples (shoot and root) were dried for 48 h at 70ºC to determine their dry matter content (yield). Total Cu and Zn concentrations in root and shoot of maize were measured after digestion plant samples by AAS method. The shoot and root uptakes were calculated by multiplying Cu and Zn concentrations by dry mass. The effects of chelating agents and maize cultivars over the measured properties were evaluated using the two-ways ANOVA. The least significant difference (LSD) was used to compare means of treatments using SAS 8.02.
Results and Discussion: The results revealed that applying both chelates caused an increase of soil available Cu and Zn contents. The maximum of soil Cu (401.9 mg kg-1 soil) and Zn (17.1 mg kg-1 soil) were obtained by using EDTA with 1.5 mmole kg-1 soil in TVC-647 and SC-704 cultivars, respectively. This was due to formation of water-soluble complexes between EDTA with Cu and Zn in soil and help in their desorption from soil particles. EDTA was more effective than CA at increasing Cu and Zn available in the soil. The results indicated that EDTA-addition in 1.5 mmole kg-1 soil significantly reduced root and shoot fresh weight in all maize cultivars compared with the control (except root fresh weight in SC-677). This reduction was due to increasing soil available Cu and Zn contents and their toxic effects on plant growth as well as toxic impacts of EDTA on soil microorganisms and growth of plant.on the other hand0.75 mmole kg-1 soil CA addition induced significant increases in root fresh weight as compared to the control (except root fresh weight in TVC-647). Application of CA in concentration level of 0.75 mmole kg-1 soil led to the greatest quantity of shoot (12.85 g pot-1) and root (21.38 g pot-1) fresh weight in TVC-647 and SC-704 cultivars, respectively. Citric acid has a natural origin and is easily biodegraded in soil. It is not toxic to plants; therefore plant growth is not limited. The highest Cu concentration in root and shoot of maize (2506.1 and 335.6 mg kg-1 dry weight, respectively) were obtained in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA – 62.2% and 422.9% greater than those obtained with control. The highest shoot Cu (871.1 μg pot-1) and Zn (76.7 μg pot-1) accumulations were recorded in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA and CA, respectively.
Conclusion: Due to importance of Cu contamination in studying soil, it is suggested that EDTA-addition at 1.5 mmole kg-1 soil can be an appropriate chelator candidate for TVC-647 maize cultivar for environmentally safe phytoextraction of Cu in soil. It is noticed that application of EDTA in soil for long time has not recommended for phytoextraction of heavy metals. Because EDTA is non biodegradable substance and can leach into ground-water and causes other environmental hazardous risks.
F. Ehsanpour; Sh. Kiani; alireza hosseinpuor
Abstract
Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields, all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use ...
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Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields, all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use efficiency of wheat (Triticum aestivum L.). A factorial experiment in randomized complete block design was carried out with two factors of type of nitrogen fertilizer (1- control: with no added N fertilizer, 2 and 3- ammonium sulfate fertilizer (ASF) with and without nitrification inhibitor DMPP, 4 and 5- ammonium sulphate nitrate fertilizer (ASNF) with and without nitrification inhibitor DMPP with rate of 100 mg N Kg-1 soil) and different levels of P (0, 30, 60 and 90 mg P kg-1 soil) on spring wheat cv. Pishtaz during 2010 at ShahreKord University with three replicates. According to results, application of nitrification inhibitor DMPP with both of ASF and ASNF resulted to meaningful increase of soil available P at the end of experiment as well as significant increase of NH4+ and also significant decrease of NO3- in the soil during experiment as compared to similar treatments but without NI. The results indicated that application of nitrification inhibitor DMPP with ASNF at all P applied led to significant increase (P
Sh. Kiani
Abstract
A pot experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP) on the nitrogen uptake, yield components, yield and grain protein content of spring wheat (Triticum aestivum L.) cv. Bahar during 2011 at ShahreKord University. A factorial experiment ...
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A pot experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP) on the nitrogen uptake, yield components, yield and grain protein content of spring wheat (Triticum aestivum L.) cv. Bahar during 2011 at ShahreKord University. A factorial experiment in randomized complete block design was carried out with two factors of type of N fertilizer (1- control with no added N fertilizer, 2-urea 3- ammonium sulphate nitrate (ASN) and 4- ASN plus DMPP) and soil type (10 soils) with three replications. The results indicated that application of nitrification inhibitor DMPP with ASN led to significant increase (P
