جستجوی مقالات مرتبط با کلیدواژه « فراهمی فسفر » در نشریات گروه « آب و خاک »

Phosphorus (P) is often lacking in calcareous soils. To investigate the effect of organic matter and elemental sulfur (S) on P availability and fractions in two calcareous soil with different textures (Clay ‌loam and Loamy sand) and total iron and aluminum concentrations, incubation studies were carried out for 12 weeks. This study was conducted in the soil science laboratory of Malayer University in 2019. The treatments include the simple treatment of sheep manure (organic matter=OM) (0, and 2 %), S (0, 0.25, and 0.5 %), and integrated treatment of OM and S in the presence of Thiobacillus bacteria. Every week, P concentration in control and treated soils was measured. At the end of incubation period, EC, pH, ECC percentage, gypsum percentage, and inorganic P fractions in control and treated soils were measured, too. At the end of the incubation period, EC and gypsum percentage increased in both treated soils. The presence of OM decreased the gypsum in soils and increased P concentration in the soils. In Clay loam soil treated with 0.25, and 0.5 percent of S, adding OM decreases the rate of P transformation, from 0.226 to 0.153 and from 0.168 to 0.154 mg kg-1 week-1, respectively and in Loamy sand soil caused an increase from 0.129 to 0.161 and from 0.125 to 0.184 mg kg-1 week-1, respectively. In both soils, simple and integrated treatments increased the dicalcium phosphate fraction and decreased the octacalcium phosphate fraction, and the apatite fraction decreased in integrated treatments. In Loamy ‌sand soil, simple and integrated treatments increased the aluminum phosphate fraction. The results showed that integrated treatment of OM with 0.25% of S in both soils increased the P availability, and despite the fixation of P in Loamy ‌sand soil, due to high total iron and aluminum content, OM increased the P availability in Loamy ‌sand soil.

The deficiency of phosphorus has attracted a lot of attention as one of the most important nutrients for agricultural plants especially in calcareous soils. However, in some soils, organic phosphorous containing 80 percent of total phosphorus in some soils but in most cases, that form of phosphorus is not available for plant uptake. The availability of phosphorus from both organic and inorganic sources by phosphate-solubilizing microorganisms (PSMs) as bio-inoculants are promising substitutes for chemical fertilizer and other agrochemicals amendments. Both arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) play a key role in providing phosphorus for agricultural plants. Among several phosphate-solubilizing fungal isolates, Aspergillus sp. is able to solubilize calcium phosphates by secreting various organic acids, e.g., oxalic and formic acids, and producing phytase enzyme. The present study aimed to evaluate the ability of different strains of Aspergillus for phytase production. The second aim of this study was the purification and application of purified phytase and its efficiency in the phosphorus availability from hexaphosphorylated inositols. Two separate experiments were carried out in two different stages. In the first one phytase was isolated from three strains of Aspergillus (Aspergillus niger provided by the department of plant protection, Agricultural college, Ferdowsi University of Mashhad), Aspergillus flavus, and Aspergillus fumigatus strains were collected from the Iranian biological resources center, Tehran). All Isolates were recultured on PDA (potato dextrose Agar) medium for 5 days at 30 oC in an incubator. Quality evaluation of phytase production by three strains of Aspergillus tested using hydrolysis of phytate sodium on PSM (phytase screen medium) medium.  Solubility index was calculated for all three strains (Solubility index = (Colony diameter + Hallow diameter)/ Colony diameter). Phytase production was carried out on fermentation media (Shieh and Ware 1968) but starch was substituted by dextrin. Fermentation media inoculated by fungal strains for 14 days at 30 oC.  Fermentation media was centrifuged (10,000 g) for 30 minutes and supernatant was collected. Purification of phytases was done against Tris-HCl 25mM, pH=7.2 for 12 hours. Phytase activities were evaluated in a completely randomized design with three replications. Then purified phytase from three Aspergillus strains was applied in a pot experiment using a completely randomized design with the factorial arrangement and three replications. The experimental factors included two levels of hexaphosphorylated inositols (and 50 mg/kg) and four types of phytase (Control, phytase isolated from Aspergillus niger, Aspergillus flavus, and Aspergillus fumigatus. In the greenhouse experiment, the effects of different phytase types on phosphorus availability from sodium phytate (hexaphosphorylated inositols) and phosphorus uptake by maize plant was evaluated. Corn plants (Zea maize 704 single cross) were grown in 5 kg pots at 70 % of water holding capacity for 60 days. Plant height, root dry weight, shoot dry weight, phosphorus concentration in shoot and root were evaluated.    The results showed that Aspergillus niger and Aspergillus flavus had the highest (4.96) and the lowest (1.23) solubility index among the tested strains, respectively. The results from the laboratory experiment showed that phytase isolated from Aspergillus niger had the maximum amount of phytase activity (16.48 µmol/ min.ml) and phytase isolated from Aspergillus flavus had the minimum phytase activity (4.67 µmol/ min.ml). Aspergillus niger phytase was more effective compared to Aspergillus flavus and Aspergillus fumigatus phytases. The results of the greenhouse experiment represented that the highest amount of phosphorous in the shoot (0.125 percent), root (0.0102 percent), and shoot dry weight (46.08 g/pot) belonged to the maize plants treated by phytase isolated from Aspergillus niger in the presence of 50 mg/kg of sodium phytate. Generally, the results showed that Aspergillus niger strain was more effective than the other two strains in both laboratory and greenhouse experiments. Phytase enzymes isolated from strains had positive effects on phosphorous concentration in a different parts of maize plant and growth characteristics of maize. Phosphatase and phytase generally improve the availability of phosphorus from different phosphorus sources. It should be kept in mind that phytase also increases the bioavailability of other essential minerals such as Ca2+, Mg2+, P, Zn2+, Fe3+, which are bound to phytic acid. Since the phytase production by fungi has been attained by different cultivation methods (solid-state, semisolid, and submerged fermentation) it seems that different cultivation methods can affect the phytase efficiency. Therefore, we suggested that phytates from different cultivation methods can be tested for phosphorus bioavailability from different sources.

In order to reduce the problems of biochar application in calcareous soils, by changing the surface properties of apple-grape biochar by phosphoric and chloric acids, the effects of enriched biochars on the fraction of phosphorus (P) forms in saline soils of Lake Urmia was investigated as a factorial incubation experiment in a completely randomized design with two factors: fertilizer treatments (control (Cont), biochar (BC), phosphate fertilizer (TSP), Biochar-Rock phosphate (BC-RP) and enriched-biochar (EB) types (BC-HCl-RP and BC-H3PO4-RP)) and 2 calcareous soils with different EC (2 and 15 dSm-1). Olsen-P, pH and different forms of inorganic P were determined by sequential extraction method at 7, 30 and 60 days of incubation. The results showed that on average, the BC-HCl-RP and BC-H3PO4-RP treatments reduced the pH of S1and S2 soils, 0.5 and 1 unit, respectively. BC-H3PO4-RP and BC-HCl-RP treatments increased Olsen-P of S1 soil from 6.7 to 57.5 and 55.5 mgkg-1 and soil S2 from 7.4 mgkg-1 to 71.3 and 62 mgkg-1, respectively. Enriched biochars significantly (p <0.01) altered the distribution and amount of inorganic P forms. Thus, BC-H3PO4-RP and BC-HCl-RP treatments increased the amount of Ca2-P fraction in the S1 soil by 2.9 and 2.6 times and in the S2 soils by 1.06 and 0.97 times, respectively. However, the amounts of Ca8-P, Al –P and Ca10-P fractions reduced significantly. Olsen-P positively and significantly correlated with Ca2-P, Fe-P, and Ca10-P fractions and positively but not significantly with the Al-P fraction, suggesting that in the extraction of Olsen-P, phosphorus is released from these mineral fractions. In general, EBs application may cause P to remain in the plant-available forms over the time. Therefore, it can help to improve P nutrition, reduce salinity stress, and eliminate the common problems of biochar application in these soils.

Millions of tons of trees pruning waste are produced annually in Iran, which can contribute to supplying soil organic matter. Soils in arid and semi-arid regions, due to lack of sufficient vegetation and the
return of low amounts of plant residues to the soil, contain little organic matter. These soils are often calcareous, and as a result, many plants in these soils are faced with nutritional problems, especially phosphorus deficiency. Phosphorus, as an essential element for plant growth, combines with soil components and changes into less soluble and insoluble compounds in calcareous soils with low amounts of organic matter. Organic matter and biological amendments can affect the solubility and mobility of nutrients in the rhizosphere and improve their bioavailability by creating different chemical and biological conditions. The pruning waste of trees can be used to produce biochar and compost and consequently improves soil physical and chemical properties and plays an important role in the dynamics and living of soil microorganisms. Biochar is a carbon-rich solid material produced during pyrolysis which is the thermal degradation of biomass under oxygen limited conditions. It has
recently received much attention as a soil amendment which can be used to increase nutrient availability, improve the soil microbial diversity and biological activities such as enzyme activity in rhizosphere and sequester carbon in agricultural soils. In addition, compost is a chemical derived product from organic waste and contains many beneficial elements that are gradually released into soil and available to plants. Another approach to improve the bioavailability and mobility of phosphorus in the rhizosphere is the use of potential of phosphatesolubilizing microorganisms including arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR). Limiting the roots to examine the biological and chemical changes and the extent to which these properties have expanded in the rhizosphere are challenges that have been less addressed Rhizobox is one of the systems used to study rhizosphere changes. The aim of this study was to investigate the effect of biochar and compost prepared from pruning waste of apples and grapes trees as well as microbial inoculation on phosphatase activity and phosphorus availability at wheat rhizosphere under rhizobox condition. This study was carried out on a completely randomized design with a factorial arrangement in three replications, under greenhouse condition in rhizobox. The factors were organic matter
(pruning waste biochar (PWB), pruning waste compost (PWC) and control (without organic matter)), microbial inoculation (AMF and PGPR) and soil type (rhizosphere and non-rhizosphere soil). For this purpose, a soil sample with light texture and low available phosphorus content was prepared. PWB used in the experiment was produced from mix pruning waste of apple and grape at the final temperature of approximately 350°C for 3 hours. Moreover, pruning waste compost of apple and grape trees was prepared from Department of Soil Science, Urmia University. The biochar and compost were ground and screened through a 0.5 mm sieve for the greenhouse experiment. The seeds of wheat were planted in 20 × 15 × 20 cm rhizobox (length, width and height). At greenhouse experiment, the biochar and compost were added to the boxes in terms of 1.5% pure organic carbon before planting (each box contained 5.8 kg of soil). In control treatments (without organic matter), sterile soil was used with microbial inoculation. Microbial strains used for inoculation included Pseudomonas aeruginosa, Pseudomonas fluorescens and Pseudomonas putida) and mycorrhizal fungus (Glomus
fasciculatum). Wheat seeds (Triticum aestivum L. cv. Pishtaz) were grown in rhizobox. At the end of the vegetative growth period, acid phosphatase (ACP) and alkaline phosphatase (ALP) enzymes activities were assayed by spectrophotometry method. Soil available P was extracted with 0.5 M NaHCO3 (Olsen-P) in the rhizosphere and non-rhizosphere soils and phosphorus concentrations in the root and shoot were determined by the standard method. The results showed that the application of PWC and microbial inoculation significantly increased ACP and ALP enzymes activity and the availability of phosphorus compared to the control. The highest increase in ALP enzyme activity and available phosphorus was observed in PWC treatment inoculated with PGPR. Furthermore, PWC increased the ACP and ALP enzymes activities in the rhizosphere soil by 1.39 and 1.33 times compared to non-rhizosphere soil, respectively. However, phosphorus availability in the non-rhizosphere soil of the PWC treatment was 21.19% higher than that in the rhizosphere soil. The lowest available phosphorus content was observed in rhizosphere soil of AMF treatment. In addition, the highest phosphorus concentrations in plant root and shoot were, respectively, found in the compost and biochar treatments inoculated with AMF. In PWB treatment, the inoculation of AMF increased shoot phosphorus concentration by 1.31 times relative to PGPR inoculation. In general, applying organic matter and microbial inoculation had a significant positive effect on phosphorus availability and plant growth. Adding organic matter to the soil, such as compost and inoculation with microorganisms particularly PGPR bacteria in the root zone, led to increased soil available phosphorus. The activity of phosphatases in soil was influenced by using organic materials such as compost and microbial inoculation which enhance the bioavailability of inorganic phosphorus. More positive interaction of PWC and PWB with AMF than PGPR in the rhizosphere caused greater increase of phosphorus bioavailability in the root zone and plant phosphorus uptake. In general, according to the results of this study, it seems that the use of organic materials and biological potential of the microorganisms have a significant effect on phosphorus availability and improve plant growth.

Phosphorus deficiency is a common disorder for agriculture in calcareous soils. To study the effects of spent mushroom compost (SMC) and sugar cane bagasse biochar (B) on alkaline phosphatase activity and phosphorus availability in three soil types (that is) loam, clay loam, and sandy loam, an incubation experiment was conducted. The treatments included levels of biochar B1 and B2 (15 and 30 ton.ha-1), levels of spent mushroom compost SMC1 and SMC2 (20 and 40 ton.ha-1) and the control (C). After applying treatments in 14, 60, and 120 days, T1, T2, and T3 respectively, available phosphorus and pH were measured and alkaline phosphatase activity at T3 period was also measured. The results indicated that in all soil samples SMC increased phosphatase activity, But biochar was ineffective in sandy loam soil. Average phosphatase activity in control treatment was 2090, 2931 and 2888 µg PNP.g-1Soil. h-1 at sandy loam, loam and clay loam, respectively and was increased to 3034, 3709 and 3533 µg PNP.g-1Soil. h-1 in SMC2 treatment, respectively. Both levels of SMC also caused increase in phosphorus availability, while biochar was less effective on that. SMC2 treatment showed the best effectiveness on increasing phosphorus availability. So that available phosphorus average was increased from19.4, 8.8 and 3.9 mg.Kg-1 in control treatments to 37, 28 and 22 mg.Kg-1 in SMC2 treatment for sandy loam, loam and clay loam soils respectively. Application of SMC reduced soils pH while biochar increased that. Results indicated that SMC has a positive effect on phosphorus availability and improves other properties including pH in calcareous soils.

Bone meal contains a large amount of phosphorus that could almost supply the phosphorus needs of crops. The main objective of this study was to determine the capability of bone meal for releasing phosphorus and its effect on growing corn. An experiment was conducted in a completely randomized design with three replications under laboratory and greenhouse conditions with 6 treatments including 400 and 800kg.ha-1 ordinary bone meal, 400 and 800kg.ha-1 acidulated bone meal, 200kg.ha-1 triple super phosphate, and control. The results demonstrated that in treatments with ordinary bone meal, phosphorus release had 30 days lag compared with triple super phosphate. Acidulation of bone meal caused faster and more release of phosphorus. The experiment also revealed that acidulated bone meal did not change the concentration of phosphorus in the shoot. However, shoot dry matter weight and phosphorus uptake by corn were significantly higher in acidulated vs ordinary bone meal. But, compared to the chemical fertilizer, their differences were not statistically significant.