The Effect of Rock Phosphate Acidification and Vermicompost on Phosphorus Release Kinetics in a Calcareous Soil

IntroductionPhosphorus (P) is one of the most important elements necessary for plant growth and production of agricultural products. In calcareous soils, phosphorus deficiency is a general issue due to high pH, high soil calcium carbonate content, lack of organic matter and moisture. Phosphorus absorption capacity depends on different soil reactions such as: adsorption, sedimentation, stabilization and release. The speed and amount of plant available P depends on the soil reactions. Studying the kinetics of P release from soil is a good indicator to check the status of P uptake by plant. The kinetics of P release in soils is a subject of importance in soil and environmental sciences. The aim of this research was to investigate the kinetics of P release and derive the most suitable equation to describe the release of P from a calcareous soil when subjected to the acidification of rock phosphate and the addition of vermicompost. Materials and MethodsIn order to investigate the ability of acidified rock phosphate and vermicompost in P release, an experiment was conducted with 2 replications on a light-textured soil with low OC and Olsen-P (1.2 mg/kg). One hundred grams air dried calcareous soil was transferred into special containers and 5 treatments including: 1- control (soil), 2- rock phosphate, 3- acidified rock phosphate (20 CC nitric acid 0.1 N and 5 g rock phosphate), 4- vermicompost, and 5- acidified vermicompost (20 CC nitric acid 0.1 N and 5 g vermicompost) were applied. The treatments incubated two weeks in 20±2℃ temperature. The Kinetics of P release was studied by adding 20 mL of 0.5N NaHCO3 to, one gram of air dried treatments. Extraction times were considered to be 0.25 h to 256 h (in 11 times) based on the time of adding the NaHCO3 extractant until filtering. After adding the extractant, the samples were shaken and centrifuged. After filtering, the concentration of released P in samples were determined by spectrophotometer (Model: CE 292 Series2, ultraviolet). For higher accuracy in the measurements, acid-washed containers were adjusted based on the amount of soil moisture which was dried in the oven (105℃). Finally, the P release data were fitted to different kinetic equations. The effect of different fertilizer treatments on P release in specified times and then kinetics parameters were investigated and compared with the control. Results and DiscussionAddition of acidified and non acidified rock phosphate and vermicompost increased the amount and speed of P release in the calcareous soil. Six kinetic equations were fitted to describe the release of P in the period of 0.25 h to 256 h from the soil to evaluate the effect of the treatments. The highest release of P was in vermicompost and acidified rock phosphate treatment, which were an organic fertilizer and a source for preparing phosphate fertilizers. To describe the release rate, kinetic equations were used. The best equations were chosen by highest coefficient of determination (R2) and the least of standard error (SE). The zero, first, second order equations could not describe the release of P in the studied calcareous soil. The R2 value decreased from the zero to second order equation. The simplified Elovich equation described well the release of P from the soil with the average R2 of 0.79 and with the average SE of 0.4. Comparison of the average effect of the studied treatments with the control showed that the acidifed vermicompost and rock phosphate treatments increased the capacity and speed of P release compared to the control. On the other hand, acid addition has increased the capacity and speed of P release in the calcareous soil. ConclusionThe findings indicated an initial rapid release of P, which then decreased over time. Notably, the application of vermicompost and the acidification of the soil with rock phosphate resulted in a pronounced and accelerated release of P. Generally, organic fertilizer treatments exhibited a higher release of P compared to chemical fertilizer treatments. This observation is in accordnce with the findings of the data presented by Ghorbanzadeh et al. (2009), who explored the P release potential of bone meal. Their data demonstrated that the acidification of bone meal accelerated and enhanced P release. To further enhance the practical relevance of these results, it is recommended to conduct this research in the presence of plants

An Investigation into Enterobacteriaceae Responsible for Early Mortality in Japanese Quail Chicks and Their Antibiotic Susceptibility Patterns

Quail is an alternative source of protein for humans. These birds can be affected by common bacterial infections. Bacterial contamination of egg is the most common cause of mortality in Japanese quail chicks. In order to study the role of some members of Enterobacteriaceae responsible for early mortality in Japanese quail chicks, 100 dead or moribund quail chicks were obtained from 10 different farms in Ahvaz, Iran. Samples were taken from the liver and yolk sac of the birds and bacterial isolation from samples was conducted by streaking them on MacConkey, Brilliant Green, Salmonella-Shigella and Xylose Lysine Deoxycholate agar plates. The plates were incubated at 37 °C for 24-48 hours, and by standard biochemical tests bacterial isolates were identified. Final confirmation of Salmonella serotypes was performed by Razi Institute. All the isolates were examined for susceptibility to 12 different antibiotics (Padtan-Teb Co., Tehran, Iran) by the disk diffusion (Kirby Bauer) method. The results showed that 78% of the quail chicks were infected. The isolated bacteria were Escherichia coli (44%), Klebsiella pneumonia (8%), Salmonella serovar ruzizi (5%), Salmonella serovar typhimurium (3%), Enterobacter cloacae (4%), Enterobacter aerogenes (4%), Proteus vulgaris (5%) and Proteus mirabilis (5%). One hundred percent susceptibility was observed to gentamycin, soltrim, tetracycline, fosfomycin, florfenicol, cephalexin and ceftriaxone. E. coli isolates were susceptible to soltrim and ceftriaxone, Salmonella isolates were susceptible to fosfomycin, Enterobacter isolates were susceptible to ceftriaxone and Proteus and Klebsiella isolates showed susceptibility to ceftriaxone. It is concluded that the members of Enterobacteriaceae family, specifically the genera Escherichia and Salmonella, are the major causes of early mortality in newly-hatched Japanese quail chicks