Exploration and effectiveness test of the potassium solvent bacteria originating from limestone mountain of Bahorok Langkat

Abstract

Plants need potassium in large quantities. The dissolved potassium concentrations are only 1-2%, meanwhile more than 90% of potassium in the soil is in the form of soluble rock. Potassium solvent bacteria facility in dissolving K. From several studies, potassium solvent bacteria can be found in limestone quarries. One of the limestone mountains in North Sumatera is the mountains in Laudamak village, Bahorok sub-district, Langkat District. This study aimed to obtain the potassium solvent bacteria and examine their potential of superior isolates from Bahorok Langkat mountain limestone. Sampling was conducted by the purposive random sampling method which was in two different locations and two different soil depths, namely on the mountain slop and foot of the limestone mountain. The ability to dissolve K was tested qualitatively by calculating the dissolution index (IP). The hypersensitivity test was carried out on tobacco leaves. The result showed that 18 isolates found from 10 soil sample from Bahorok Langkat limestone mountain were able to dissolve K in the Aleksandrov medium, there were 11 isolates that were able to dissolve K and 11 of selected isolates were not pathogenic to plants.