To develop biofertilizers for rice in Afghanistan, 98 plant growth-promoting rhizobacteria were isolated from rice plants and their morphological and physiological characteristics, such as indole-3-acetic acid production, acetylene reduction, phosphate and potassium solubilization, and siderophore production, were evaluated. The genetic diversity of these bacteria was also analyzed based on 16S rRNA gene sequences. Of 98 bacteria, 89.7% produced IAA, 54.0% exhibited nitrogenase activity, and 40% showed phosphate solubilization and siderophore production. Some isolates assigned to Pseudomonas (brassicacearum, chengduensis, plecoglossicida, resinovorans, and straminea) formed a relationship with rice, and P. resinovorans and P. straminea showed nitrogen fixation. Rhizobium borbori and R. rosettiformans showed a relationship with rice plants and nitrogen fixation. Among the isolates examined, AF134 and AF137 belonging to Enterobacter ludwigii and P. putida produced large amounts of IAA (92.3 μg mL−1) and exhibited high nitrogenase activity (647.4 nmol C2H4 h−1), respectively. In the plant growth test, more than 70% of the inoculated isolates showed significantly increased root and shoot dry weights. Highly diverse bacterial isolates showing promising rice growth-promoting traits were obtained from Afghanistan alkaline soils.

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Studies on soil-landscape relationships are necessary to improve our understanding of the spatial distribution and variation of soils for their sustainable management. This study evaluated the relationship between soil properties and landscape position in the northern volcanic mountain of Leyte, Philippines. Five soil profiles located on summit, shoulder, backslope and footslope positions were evaluated. Findings revealed that the degree of soil development as well as the soil morphophysical and chemical properties varied with landscape position. The soil in the most stable position (summit) had thicker solum and slightly more developed soil profile than the soils in other landscape positions. On the other hand, soils in the unstable position (backslope) generally had thinner solum. All the five soils also revealed the influence of the andesitic volcanic parent material on their properties. They all showed some properties typical of Andisols such as low bulk density and high pH in NaF although they were classified as Andic Dystrudept. The soils all possessed physical and chemical constraints for crop production.

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