Soil science
H. Hatami; H. Parvizi; A. Parnian; Gholamhassan Ranjbar
Abstract
IntroductionThe availability of phosphorus (P) is a limiting factor for the production of crops due to its reactions with soil components. Furthermore, there are concerns about the depletion of non-renewable global rock phosphate (the main source of P) reserves because of the high demand for P fertilizers. ...
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IntroductionThe availability of phosphorus (P) is a limiting factor for the production of crops due to its reactions with soil components. Furthermore, there are concerns about the depletion of non-renewable global rock phosphate (the main source of P) reserves because of the high demand for P fertilizers. Therefore, it is essential to revisit existing agricultural practices to determine new resource management practices that utilize renewable resources. The application of sewage sludge could be an alternative P source; contrary to inorganic fertilizers, sewage sludge is cheap, contains nutrients, and improves soil quality due to contained organic matter. The total P content of sewage sludge may vary from less than 0.1% to over 14% on a dry solid basis, depending on the nature of the raw sewage being treated and the treatment process under consideration. However, the use of organic P resources can affect the soil chemistry, leading to changes to the P fractions and their quantities. Hence, the objective of this study was to compare the effect of the application of municipal sewage sludge and triple superphosphate on the distribution of soil-P fractions under saline and non-saline conditions.Materials and MethodsTo investigate the effect of municipal sewage sludge and triple superphosphate on changes in P fractions an incubation experiment was conducted in a completely randomized factorial design with three levels of triple superphosphate (0, 75, and 100 Kg ha-1 which were named T0, T1, and T3, respectively), three levels of municipal sewage sludge (0, 0.25 and 0.5% w/w which were named M0, M1 and M3, respectively), two levels of salinity of irrigation water (2 and 12 dS m−1, which were named saline and non-saline, respectively) and three replicates. The total number of samples was 54. The treated soils were incubated for three months and maintained at field capacity by adding the appropriate amount of saline and non-saline waters. P fractionated to KCl-P (soluble and exchangeable P), NaOH-P (Fe- and Al bound P), HCl-P (Ca-bound P), Res-P (residual P), and organic-P by sequential extraction method. Moreover, P percentage recovery for Olsen-P at each treatment was calculated. P concentration in samples was determined by the molybdate method. Data analysis was performed by MSTAT-C software, and the means were compared at α꞊5% by Duncan test. Results and DiscussionThe results showed that although the relative distribution of fractions followed the order of HCl-P < Organic-P < KCl-P < NaOH-P <Res-P, the changes in each fraction were dependent on the type of treatment and fraction. The amounts of KCl-P for application of municipal sewage sludge and fertilizer TSP combined, especially, T2M2 were 3.1 and 2.3 times higher than T0M0 in non-saline and saline conditions, respectively. The same result was obtained for NaOH-P. The combined and separate application of municipal sewage sludge diminished the relative distribution of HCl-P compared with triple superphosphate and control treatments in both salinities. However, the HCl-P in all treatments was more than 57% of the total P, suggesting that most of the soil P was in the carbonate phase. The treatments did not have a considerable impact on Res-P. The relative distribution of Organic-P increased by increasing levels of salinity and municipal sewage sludge. Therefore, it seems that municipal sewage sludge addition along with fertilizer P can reduce the negative effects of salinity and increase soil P availability compared with alone use of P fertilizer through growing the contents of KCl-P, NaOH-P, and organic-P fractions and, consequently, decreasing P entry into HCl-P fraction. Moreover, the application of municipal sewage sludge plus triple superphosphate increased P recovery as Olsen-P compared to a separate application of triple superphosphate which confirmed the advantage of the combined use of these sources.ConclusionThe findings of this study indicate that the simultaneous application of municipal sewage sludge and triple superphosphate can effectively improve phosphorus (P) availability in saline conditions. This enhancement is attributed to the alteration of the relative distribution of non-stable P fractions, such as KCl-P and NaOH-P, which increase, while stable P fractions like HCl-P decrease. Moreover, the addition of municipal sewage sludge into soils led to a significant increase in organic C as well as the relative distribution of organic-P. Therefore, application of municipal sewage sludge can improve the physico-chemical properties of saline soil along with increase of P availability. Hence, further research on the growth response of halophyte plants as affected by these treatments is recommended.
Reza Pourimani; Faeze Yousefi
Abstract
Introduction: Humans are constantly exposed to ionizing radiation. Most of the radiations originate from radioactive decay of natural radionuclides in the environment. Most of the ionizing radiations resulting from the decay of natural radioactive series of 238U, 235U, 232Th and 40K radionuclides in ...
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Introduction: Humans are constantly exposed to ionizing radiation. Most of the radiations originate from radioactive decay of natural radionuclides in the environment. Most of the ionizing radiations resulting from the decay of natural radioactive series of 238U, 235U, 232Th and 40K radionuclides in soil, rock and water. The average amount of uranium in the earth's crust is estimated 2.7 mg/kg that its amount increases up to 120 mg/kg in phosphate rocks. Phosphate rocks are main row material of chemical fertilizers production. Chemical fertilizers are chemical compounds that are used in order to increasing crops and improving properties of land. Yearly, many different types of fertilizers are produced such NPK, phosphate, etc.. Even though fertilizers can improve nutrient-deficient symptoms in farms but they contain heavy metals and radionuclides. Radionuclides in fertilizer enter to the soils and directly or indirectly can be absorbed by human body by inhalation of the radon gaseous or consumption of foodstuff. Radium salts with other salts are also dissolved in water and penetrate to deep layers of soil and can cause groundwater pollution. The consumption of chemical fertilizers containing radionuclides increases the radiological parameters of soils. Nuclear radiations is emitted from these elements are harmful to the body's tissues and may cause diseases such as cancer or genetic abnormalities. Therefore, the investigation of natural radioactivity contents in soils and radiological parameters are very important. In this research, the specific activities of natural radionuclides in agricultural and virgin soil samples determined using gamma ray spectrometry method in Arak and Saraband cities in Markazi province, Iran..For all samples, radiological parameters were calculated and compared with world average and some countries.
Materials and Methods: In this study, twenty two samples of agricultural and virgin soils were collected in different areas of Arak and Saraband cities of Markazi province in Iran, from surface up to 30 cm depth. The weight of each sample was about 2 kg. After drying the samples at room temperature, they were powdered by electric mill in the laboratory of Arak university. Soil samples were pulverized and passed through a 0.297mm sieve. They were kept in oven for 24 h at 100°C in order to remove the moisture content. After that, 950 g of each sample was packed in a Marinelli beaker container and sealed. Gamma ray spectra were registered after 50 days. The collected samples required particular care since radon is a short-lived gaseous nuclide and tends to escape from the samples. In this work, standard containers were sealed. After the minimum 50 days of preparing samples, gamma ray spectra were registered. This time is necessary for taking radioactive decay chain equilibrium, in which the decay rate of the daughters became equal to that of the parents. Specific activity measurements were performed by gamma ray spectrometry method employing high purity germanium (HPGe) P-type coaxial detector (GCD30195BSI) manufactured by Baltic Scientific Instrument LTD (005-Latvia) with 30% relative efficiency, which was connected to a multi-channel analyzer of 8192 channels. The energy resolution (full width at half maximum) of this detector is 1.95 keV for gamma energy line at 1332.520 keV due to 60Co and a Peak-to-Compton ratio of 60, and operating voltage was 3000 V. The detector and preamplifier are shielded in a chamber of three layers composed of 10 cm thick lead, 1.5 mm thick cadmium, and 3 mm thick copper. This shield serves to reduce background radiation.
Results and Discussion: Based on the results, the specific activities of 226Ra, 232Th and 40K radionuclides in soil samples varied in the range (39.60-51.94), (50.90 – 73.84) and (676.09 – 1094.50) in agricultural soils and (12.98 – 61.60), (18.15 – 60.98) and (257.48 – 866.58) in virgin soils, in Bq/kg. The mean specific activities of corresponding radionuclides were obtained 45.54, 69.09 and 926.71 Bq/kg for agricultural soils and 37.26, 43.17 and 604.04 Bq/kg for virgin soils. For all results calculated and have been tested variety of variance which show increasing in agriculture soil amount of 232Th and 40K compared with virgin soil. For 226Ra, the significant variation in probability level of 0.05 was not observed because of more mobility of radium salt than other salts and penetration into deeper layers. The increases the amounts of studied radionuclids in agricultural soils compared with average of worldwide virgin soils are 74.12, 72.30 and 131.68 percent, respectively. The average absorbed dose in air calculated for agricultural and virgin soils that obtained 105.22 and 70.59 in nGy/h, respectively. The average of Annual Gonadal Dose Equivalent (AGDE) and Excess Lifetime Cancer Risk (ELCR) for agricultural and virgin soils were obtained as (0.72 and 0.48) and (0.45×10-3 and 0.29×10-3), respectively. For virgin soil samples, radiological parameters were in good agreement with mean world value but in agricultural soil samples, increase was observed compared to virgin soil and agricultural soils of some countries.
Conclusions: The obtained data showed that the amount of mean specific radioactivity of natural radiouclides in agricultural soils were higher than some countries. The radiological parameters of agricultural soils in most samples were more than the world average of virigin soil values. The results of this research on virgin soil were in good agreement with the world average. This study showed that consumption of fertilizers in these cities was more than other countries. But all of radiological parameters of soil samples were less than maximum acceptable criteria and thus have no damaging effect for people health. However, the long term unsuitable usage of chemical fertilizers can have the effect of increasing of radioactivity in soils that can be harmful for the health of farmers and consumers of the crops.
A. i Yadav; Z. Yuosepur
Abstract
Introduction: Soil fertility management is a key factor in achieving sustainable agriculture. Use of organic fertilizers is one of the methods that without environmental harmful effects with improvement of chemical and biological conditions increases soil fertility. Nitroxin contains a collection of ...
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Introduction: Soil fertility management is a key factor in achieving sustainable agriculture. Use of organic fertilizers is one of the methods that without environmental harmful effects with improvement of chemical and biological conditions increases soil fertility. Nitroxin contains a collection of the best strains of nitrogen fixation bacteria of the genus Azospirillum and Azotobacter. These bacteria through atmospheric nitrogen fixation and the balance of macro and microelements needed for plant uptake, stimulate the growth and development of roots and aerial parts of the plant. Phosphate Barvar2 is another bio-fertilizer which contains set of phosphate solubilizing bacteria of different genera Bacillus and Pseudomonas that can change soil insoluble phosphorus into available forms for plants. The purpose of this study was to evaluate some chemical properties of soil and nutrient concentrations in leaves and seeds of sunflower under the influence of chemical and biological form of nitrogen and phosphorus fertilizers to reduce the use of chemical inputs and to improve quality traits in sunflower.
Material and Methods :The experiment was carried out in a split factorial based on RCBD with three replications in a field in Eivanegharb (Ilam province) in summer of 2011. The main plot included four levels of phosphorus and nitrogen chemical fertilizer (0, 33, 66 and 100% of nitrogen and phosphorus fertilizer requirements) and subplot included factorial of Nitroxin bio-fertilizer application with two levels (inoculation and non inoculation) and Phosphate Barvare2 bio fertilizer with two levels (inoculation and non inoculation). Each plot consisted of 5 rows at a distance of 60 cm and a length of 6 m and 20 cm plant spacing. At the time of flowering, leaves were harvested for measurement of nitrogen, phosphorus, potassium, zinc and manganese. After harvesting, the amount of total nitrogen, phosphorus and potassium and pH of the soil and the concentrations of nitrogen, phosphorus, potassium, zinc and manganese seed were measured.
Results and Discussion: The residual soil nitrogen: Based on these results, the effect of any of the factors tested for the residual soil nitrogen was not significant.
The remaining soil phosphorus: With the increased use of chemical fertilizer, soil phosphorus increased so that the maximum (54.5 mg kg-1 soil) and minimum (40 mg kg-1 soil), available soil phosphorus levels were recorded in consumption of 100% of the required fertilizer and control treatments. Nitroxin and Phosphate Barvare2 applications increased percentage of soil phosphorus, i.e. 12.7 and 23.6 %, respectively, compared to no fertilizer application.
The remaining soil potassium: Comparison of mean values showed that the increase in use of nitrogen and phosphorus fertilizer requirements reduced potassium levels in the soil, so that the maximum amount of soil potassium (624.9 mg kg-1 soil) belonged to control chemical fertilizer treatment and the minimum value of this attribute (514.4 mg per kg of soil) was related to the use of 100% chemical fertilizer consumption with no significant difference with use of 66% chemical fertilizers treatment.
Soil pH: Among the experimental factors studied only bio-fertilizer Phosphate Barvar2 had a significant effect on soil pH at 5% probability so that the use of bio-fertilizer Phosphate Barvar2 significantly decreased soil pH.
Leaf nitrogen: By increasing the amount of chemical fertilizer used, leaf nitrogen content increased, so that the maximum amount of leaf nitrogen (2.5%) was observed in the use of 100% chemical fertilizer consumption treatment. However, no significant difference was recorded in the use of 66% chemical fertilizers tratment. The lowest of this trait (2.2%) belonged to control chemical fertilizer treatment without significant difference with use of 33% chemical fertilizers consumption treatment.
Seed nitrogen: Chemical fertilizer and Phosphate Barvar2 had significant effects on the amount of seed nitrogen content. With the increasing use of chemical fertilizers seed nitrogen increased so that the maximum (2.9%) and minimum (2.6%) seed nitrogen content belonged to use 100% of the chemical fertilizer and non-application of fertilizer, respectively. Mean comparison effect of Phosphate Barvar2 inoculation revealed that seed nitrogen increased by 3.7%.
Seed phosphorus: Analysis of variance showed that the amount of seed phosphorus significantly was affected by the treatments, i.e. Nitroxin and Phosphate Barvare2 as well as the interaction of chemical fertilizer and Nitroxin. Application of Phosphate Barvar2 increased the amount of seed phosphorus by 14.8%.
Seed potassium: Increasing application of chemical fertilizer requirement increased seed potassium. Among the 0, 33, 66 and 100% chemical fertilizer application treatments, Phosphate Barvare2 inoculation increased seed potassium by 23.3, 31.2, 31.3 and 11.4%, respectively.
Seed zinc: According to the analysis of variance, effect of bio-fertilizer Phosphate Barvar2 and interaction of Phosphate Barvar2 and chemical fertilizer on the amount of seed zinc were significant different. However, only in 100% chemical fertilizer requirement, Phosphate Barvare2 inoculation showed significant difference in this trait (63.4% increase).
Seed manganese: The results showed that factors of Nitroxin and Phosphate Barvar2 and also the interaction of Phosphate Barvar2 and chemical fertilizer had significant effects on seed manganese content. Sunflower seed inoculation with Nitroxin increased the amount of seed manganese by 37%.
Conclusion: According to the results, the maximum increase in the amount of nutrients studied in leaves and seeds of sunflower and soil was obtained in combined use of chemical and biological fertilizers.
Keywords: Biofertilizer, Chemical Fertilizer, Nitroxin, Phosphate Barvare2, Seed Elements, Sunflower
H. R. Boostani; abdolmajid ronaghi
Abstract
Sewage sludge (SS) as a source of required plant nutrients has been utilized in many countries for crops production. for investigation of SS application affect in compared to chemical fertilizer treatment (F), on dry matter yield (DMY) and concentration of some macro and micro nutrient in corn, a greenhouse ...
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Sewage sludge (SS) as a source of required plant nutrients has been utilized in many countries for crops production. for investigation of SS application affect in compared to chemical fertilizer treatment (F), on dry matter yield (DMY) and concentration of some macro and micro nutrient in corn, a greenhouse experiment (5 × 3 factorial) arranged in a completely randomized design with three replicates was conducted. The first factor included SS levels (0, 10, 20, 40 and 80 gr kg-1 soil) and the second factor was soil textural classes (clay loam, sandy loam and sandy). A chemical fertilizer treatment was also used to compare its affect with that of SS application levels on growth and chemical composition of corn. For comparison of applied SS levels (one factor) with chemical fertilizer treatment in each soil textural classes was used from a completely randomized design with six treatment and three replicates. The results indicated that addition of SS significantly increased DMY of corn in all textures. Application of SS significantly increased N, P, Fe, Zn, Cu and Mn concentration in corn aerial parts and nutrients deficiencies symptoms disappeared. Nutrients concentrations in corn plants did not reach to toxic levels even at high rates of SS application and concentration of Cd and Pb were negligible and not detectable in shoot corn. Based on nutrient deficiency in calcareous soils especially Zn and Fe, application of SS for contrasting with shortage of these elements can be effective way to eliminate these nutrients shortage. In general, application of SS was superior to chemical fertilizer treatment in increasing concentration of nutrients and DMY of corn. Prior to any SS recommendations the results of this experiment needs to be verified under field conditions.
