Application and Non-Application of Sulfur in the Formulation of Pseudomonas fluorescens Phosphatic Microbial Fertilizer on Corn (Zea mays L.)

Phosphatic microbial fertilizers (PMFs) which produced from organic (Bagasse) and chemical (Rock phosphate and Sulfur) materials with combination of phosphate solubilizing bacteria (PSB) are taking more concerns in recent researches. These products are being used in two forms; granular or powder, to meet plant P demand. But application of sulfur in this formulation was the main reason of this research, whether the application of S in this context is useful or not? According to this main question, application and non-application of elemental sulfur in produced PMFs were evaluated in this study. This PMF was made after preparing the initial appropriate population (107 CFU/g) of the bacteria Pseudomonas fluorescens in the context of rock phosphate (45 g), bagasse (30 g) and sulfur (15 g). The treatments included the control (without adding any bacteria or PMF), microbial fertilizers bed without adding bacteria (or carriers) and PMFs in two levels of consumption (0.6 g and 1.2 g) based on soil analysis test. The results of greenhouse experiment showed that the addition of sulfur in the formulation of microbial fertilizers not only doesn’t have any inhibiting effect on bacteria but also increases all the indices of growth and plant nutrient. Application of sulfur in phosphatic microbial fertilizers had significant increase on total wet and dry weight of shoot (50.48 and 20.62 %, respectively) and root (41.85 and 42.47 %, respectively), the content of phosphorus, potassium, iron and zinc in the root (45.86, 58.01, 45.09 and 76.33%, respectively) and shoot (28.66, 29.79, 50.08 and 67.23%, respectively) of corn variety S.C.704. Inoculation with microbial fertilizers and plant growth promoting bacteria P. fluorescens with chemical element sulfur led to rhizosphere colonization and caused an increasing effect on plant growth and its nutrition. It seems that addition of sulfur not only has not a negative effect on P. fluorescens bacteria but also the positive effects of this fertilizer have improved.