Showing 7 results for Fractions
A. Halajnia, G. H. Haghnia, A. Fotovat, R. Khorasani,
Volume 10, Issue 4 (1-2007)
Abstract
Study of phosphorus reactions over time and the role of organic matter in the calcareous soils are important for the development of P fertilizer and manure management practices. The objective of this study was to determine the effect of applied manure on P availability and its chemical forms in the soil, over time. Eight samples were collected from semi-arid calcareous soils of Mashhad plain. The samples were treated with two levels of inorganic P (0 and 300 mg P kg-1 soil as KH2PO4) and two levels of organic matter (0 and 1% cattle manure). The experiment was conducted in a completely randomized design with factorial arrangement. The treated soil samples were incubated for 2, 5, 10, 30, 60, 90 and 150 days, then analyzed for available P (Olsen-P). The result showed that only 17% of added phosphorus was available in P treatment at the end of experiment. In manure treated soils, this figure reached 34% for the same period of time. Application of manure along with P increased the recovery of applied P and CBD-P (Citrate-Bicarbonate-Dithionite). This may be due to the formation of P-organic complexes with Fe oxides. Application of manure in soil increased NaCl-NaOH-P considerably compared with P and P+OM treatments. It can be concluded that P originating from manure compared with inorganic-P may be more available for plants over the time.
R. Dehghan, H. Shariatmadari, H. Khademi,
Volume 11, Issue 42 (1-2008)
Abstract
Studying soil phosphorus fractions is useful in understanding soil pedogenesis as well as soil fertility. In this reseach, 20 soil samples were taken from different depths of 0-30 and 30-60 cm of upper-slope, mid-slope and lower-slope positions of four toposequences in arid (Jei and Ziar in Isfahan) and semiarid (Farokhshahr and Shahrekord) regions. In each toposequence, the soil depth was relatively low at the upper-slope position and increased toward the lower-slope. The soils in upper-slope and mid-slope were under scarce native vegetation where the soil in lower-slope was under farming activities. Soil phosphorus (P) fractionation was carried out using sequential extraction. The total soil phosphorus was in the range of 302-1135 with an average of 715 mg/kg. About 65-89% of total phosphorus were inorganic, and 11-35% organic. The amount of inorganic and organic P in the soil samples was in the range of 204-897 with an average of 571, and 70-238 with an average of 114 mg/kg, respectively. The amount of total, inorganic and organic P increased from upper-slope toward the arable lands and decreased from topsoil to subsoil in all toposequences. In the studied soils, apatite ( Ca10-P ), aluminum phosphates(Al-P), octacalcium phosphates( Ca8-P ), iron phosphates (Fe-P), iron oxides occluded phosphates( OC-P ) and dicalcium phosphates( Ca2-P ) were the major constituents of the soil inorganic phosphates, respectively.
H. R. Motaghian, A. R. Hosseinpur, F. Raiesi, J. Mohammadi,
Volume 18, Issue 67 (6-2014)
Abstract
Rhizosphere is a small zone and has quite different chemical, physical, and biological properties from bulk soil. This research was performed to study the available Zn and its fractions in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Zn using 7 chemical procedures and Zn-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (P<0.01). Zn extracted using several chemical extractants (except 0.01 M CaCl2) in the rhizosphere were significantly (p<0.05) higher than in the bulk soils. Also, concentrations of Zn-fractions (except carbonate-associated) in the rhizosphere were significantly (p<0.05) different from concentrations of Zn-fractions in the bulk soils. Results indicated that correlation between uptake index and extracted Zn using DTPA-TEA and Mehlich 3 were significant (p<0.05). Moreover, significant correlation (p<0.05) between uptake index and exchangeable Zn and Zn associated with iron-manganese in the wheat rhizosphere and bulk soils were found. The results of this research illustrated that available Zn and its fractions in the rhizosphere soils are different from the bulk soils. Therefore, application of the rhizosphere soil would be recommended in the study on these properties after planting.
N. Najafi, H. Towfighi,
Volume 18, Issue 67 (6-2014)
Abstract
Phosphorus behavior in waterlogged soils is significantly different from non-waterlogged soils. Changes in available phosphorus and inorganic phosphorus fractions after waterlogging in the paddy soils of north of Iran were studied in a laboratory research. A factorial experiment in a completely randomized design with two replications was performed with factors of soil at 14 levels (10 alkaline-calcareous and 4 non-calcareous or acid soils) and duration of waterlogging period at three levels (0, 30, 90 days). At the end of waterlogging period, phosphorus fractions in calcareous soils by Jiang and Gu method and in non-calcareous soils by Kuo method and available-P by Olsen method were determined. The results showed that the level of available-P in all soils was increased 90 days after waterlogging (on the average 2.3 times). In general, all P fractions were changed significantly after waterlogging and the amount of change was different depending on P fraction, soil type, and duration of waterlogging period. These results indicated the complex behavior of P in soils. The Al-phosphates were increased in 12 out of 14 calcareous and non-calcareous soils 90 days after waterlogging compared with air-dry soil. The Fe-phosphates were decreased in 9 out of 10 calcareous soils 90 days after waterlogging compared with air-dry soil while the effect of duration of waterlogging period on the Fe-phosphates in non-calcareous soils was not significant. The readily soluble-P in non-calcareous soils increased 30 and 90 days after waterlogging. The results indicated that some inorganic P fractions transformed into other fractions and probably organic P transformed into inorganic P during soil waterlogging period.
A. Reyhanitabar, K. Khalkal, N. Pashapour,
Volume 21, Issue 3 (11-2017)
Abstract
In this research available iron was measured in 21 calcareous surface soil samples (0-30 cm) by five methods including DTPA, AB-DTPA, AC-EDTA, hydroxylamine, reference ammonium oxalate and rapid ammonium oxalate. Fe fractions were also determined by the modified sequential extraction procedures introduced by Singh et al. According to results, rapid ammonium oxalate and AC-EDTA methods extracted the maximum (856.03 mg.kg-1) and minimum (4.46 mg.kg-1) amounts of Fe, respectively. Rapid ammonium oxalate extraction method, in addition to Fe-Afeox, extracted other fractions of iron such as Fe-Ex, Fe-Om, Fe-CFeox and Fe-Res. Hydroxylamine method compared to other methods, ectracted Fe mostly from the amorphous oxides source. Regression analysis indicates that Fe-Ex, Fe-AFeox and Fe-Res fractions have major and Fe-Car and Fe-Mnox have minor role in releasing available Fe (with AB-DTPA and DTPA) in the studied soil. According to the statistical relationships, carbonates associated Fe, does not seem a potential source of available Fe in calcareous soils. Organic carbon content and cation exchange capacity of the soils appear the two most influential soil properties that predict available Fe in the studied soils.
A. Cheraghi Tabar, E. Adhami, H. R. Owliaie,
Volume 22, Issue 4 (3-2019)
Abstract
The present study was conducted to evaluate zinc availability and forms, as well as their relationships with soil properties in some soil samples of Kermanshah and Ilam provinces. Sequential extraction included Mg(NO3)2 (soluble + exchangeable), NaOAc pH = 5 (carbonatic fraction), Na-hypochlorite at pH = 8.5 (organic fraction), hydroxylamine hydrochloride at pH 2 (Mn oxides associated Zn), hydroxylamine hydrochloride (amorphous Fe oxides associated Zn), ammonium oxalate (crystalline Fe oxides associated Zn), and HNO3 (the residual Zn). DTPA-Zn was in the range of 0.34-3.7 mg/kg. The results showed that soluble+ exchangeable, Mn oxides and crystalline Fe oxides associated Zn were not detectable by atomic absorption. Distribution of Zn fractions was in the order of Organic-Zn < Car-Zn < amorphous Fe oxides-Zn < Res-Zn. Organic matter bound Zn and amorphous Fe oxides associated Zn and the residual fractions showed a significant negative correlation with the calcium carbonate equivalent. It seemed s that calcium carbonates were the major factor in controlling the Zn content in the studied soils.
F. Shahbazi, A. R. Hosseinpur, H. R. Motaghian,
Volume 24, Issue 1 (5-2020)
Abstract
In order to increase the available Phosphorous (P), chemical fertilizers are applied; however, P chemical fertilizers are transformed into low available forms over time. Organic amendments could be effective in improving the efficiency of P fertilizers. The aim of this study was to investigate the effect of P fertilizers and vermicopost on the availability and fractions of P and maize (Zea Mays L.) indices in a calcareous soil. This study was performed in a factorial completely randomized design with three replicates. The experimental factors included chemical fertilizer (0 and 50 mg/kg P) and vermicopost (0 and 1 %W). After 2 months of planting in greenhouse, the shoots of maize were removed and the maize indices (P concentration, dry matter and P uptake) were determined. Then, the soil samples taken from each pot, P available, and P fractions were evaluated by a modified method developed by Hedley et al (1982). The results showed that the effect of the interaction beyween P fertilizer and vermicopost on the available P was significant. Also, the interaction of P fertilizer and vermicopost on the soluble and exchangeable P (P<0.05) and organic P (P<0.01) was significant. By applying the P fertilizer or % 1 vermicompost, all P fractions (except Ca bound P) were increased. The results, therefore, showed that the effect of the interaction between P fertilizer and vermicopost on P concentration, dry matter and P uptake was not significant (P>0.05). Vermicopost application increased the dry matter from 6.9 to 10.5 g pot-1, while application of 50 mg kg-1 P as fertilizer increased the dry matter from 7.7 to 9.7 g pot-1. Also, by adding vermicopost (11.1%), the i P uptake was increased, as compared to 50 mg kg-1. The results, therefore, indicated that the beneficial effect of vermicompost on the dry matter and P uptake in maize was more than that of the chemical fertilizer. Moreover, P fertilizer and manure could influence P fractions and P availability.
