Significance of Some Soil Amendments and Phosphate Dissolving Bacteria to Enhance the Availability of Phosphate in Calcareous Soil

Abstract

Two field experiments were conducted to study the effect of Arbuscular Mycorrhizal fungi (VAM) and phosphate dissolving bacteria (PDB) application on soil phosphate availability to barley plant grown in calcareous soil. The experiments were carried out at experimental research station-Ras Sudr, Desert Research Center in winter seasons of 2015-2016 and 2016-2017. Biofertilizers treatments were: control, Glomus macrocarpium (VAM) and Bacillus megatherium (PDB) either single or mixed application. Phosphorus fertilizers were applied from two sources, mono super phosphate (MSP) and rock phosphate (RP) at rates of 50, 75 and 100% of the recommended dose. Application of MSP fertilizer significantly increase of grain, straw and biological yield during both growing seasons by 2.7, 2.1 and 2.3%, respectively as compared to rock phosphate fertilizer treatment. Dual inoculation with VAM and PDB increased significantly nitrogen and phosphorus concentrations in the grain and straw. The plant height, grain and straw dry weight per plant, 100 grain weight were increased by 7.5, 8.9, 14.8 and 15.8%, respectively and the grain, straw and biological yield increased significantly by 13.4, 20.6 and 18.1%, respectively compared with the un-inoculated treatments. The highest significant biological yield (5.248 t/ha) was obtained under MSP, 75, VAM+PDB treatments.

Assessment of the Effect of Glycine, Oxalic Acid and Nitrogen-Phosphorus-Potassium (NPK) Fertilizer as Nutrient Supplement Using Phosphate and Oxalic Acid as Indices

“…Oxalic acid and glycine which released higher amounts of phosphate in the study may be due to their ability to lower the pH which increase solubilisation, displacement and liberation of insoluble phosphate, increase saturation of adsorption sites and decrease binding energy that offer greater stability [9,19,20]. The addition of glycine and oxalic acid will be more effective for the treatment of phosphorus deficiencies in soils, useful for application in plants which requires higher phosphorus content for survival, beneficial support for improvement and restoration of vegetation.…”

“…The higher release of phosphate in oxalic acid can be attributed to its lower pH in solutions due to the presence of two carboxylic groups and its potential to enhance phosphorus availability in ecosystems while the lesser release of phosphate in glycine may be due to the fact that it is neutral in solutions [2,17,18]. NPK which released the least amount of phosphate can be attributed to the alkalinity of the soil which have must caused the conversion of phosphate in the fertilizer to tricalcium phosphate a form which is unavailable to the soil [19]. This study showed that more phosphate was released as the nutrients stayed longer in the soil.…”

“…This study showed that more phosphate was released as the nutrients stayed longer in the soil. Increased phosphate presence essentially reduces soil pH, enhances nutrient uptake, increases chlorophyll content and rate of photosynthesis [19]. Higher phosphate implies low mobility and greater saturation that offers greater chemical solubilisation stability.…”

“…This confirms literature reports that the addition of low molecular weight organic acids immobilize phosphate and make them available for plant uptake. It is also worthy of note that the use of organic acids can replace phosphorus containing fertilizers which would address the problem of phosphate leaching and ensure the safety of the environment [9,19].…”

Importance of phosphate pock application for sustaining agricultural production in Egypt

“…To evaluate the best combination of phosphate rock (RP), sulphur (S), organic manure, and phosphate-dissolving bacteria (PDB) inoculation to enhance the availability of phosphorus from phosphate rock and their effects on yield of broad bean plants (Khalil 2013). Results concluded that sulphur application or PDB inoculation with RP had a significant effect on broad bean yield and its quality.…”