Potential of phosphate solubilizing microbes from Andisol in qualitatively dissolving P at various pH

¹ Graduate school of Agriculture Sciences, Faculty of Agriculture, Universitas Sumatera Utara, Medan 20155, Indonesia
² Faculty of Agriculture, Universitas Sumatera Utara, Medan 20155, Indonesia
³ Research Center for Horticultural, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Indonesia

^* Corresponding author: agus196@brin.go.id; t.sabribna@usu.ac.id

Abstract

Plants require P nutrients to grow, develop, and produce yields. Andisols are often used as agricultural land, but this soil has low available P and high P retention (97.8%). Using phosphate-solubilizing microbes (PSM) can increase phosphate solubility. The dissolution of P by phosphate-solubilizing microbes is greatly influenced by environmental factors, one of which is pH. This research aimed to determine the potential of PSM from Andisol in qualitatively dissolving phosphate at various pH levels. The study used a completely randomized design with the treatment factor is a type of phosphate solubilizing microbes (T11, T21, SE, BJ11, BJ12, BJ22, P1, P2, SP11, SP12, SP21, SP22, P13 (F), P12 (F), BJ21 (F), BJ23 (F)). The results of the research show that the phosphate solubilizing microbe that has the potential to produce the highest dissolution index at pH 4 is Bacillus sp T11, followed by Bacillus sp P11 and Bacillus sp P21, at pH 5 is Bacillus sp P11, at pH 6 is Burkholderia sp SP12 and followed by Bacillus sp SE and at pH 7 is Burkholderia sp SP12. The maximum P dissolution index occurred 4 days after planted (DAP) in pH 4, pH 5, and in pH 6, 7 at 6-10 DAP. Correlation of colony diameter and P dissolution index at pH 4-7 shows a strong relationship, where the larger the colony diameter, the smaller the dissolution index, respectively, the percentages are 81%, 89%, 91%, and 95%.