Recent studies have described the potential of rock biofertilizersproduced from natural phosphate- and potassium-bearing rocksand mixed with sulfur inoculated with Acidithiobacillus oxidizingbacteria to increase nutrient availability due to the acidity producedby the sulfuric acid, which acts to release nutrients from the min-erals contained in the rocks (Stamford et al., 2007, 2008; Bergeret al., 2013). Because of this acidic reaction, PK rock biofertilizersare an important factor whose potential has not been fully studied,especially in arid and semiarid conditions with alkaline soils.