Effect of Enriching Vermicompost with Azotobacter and Bacillus Bacteria and Foliar Spraying with Azotobacter on Some Chemical Characteristics of the Soil Planted with Sunflower Plants

A field experiment was carried out at the research station of the Department of Soil Sciences and Water Resources of the College of Agriculture/University of Diyala in 2022 to study the effect of enriching vermicompost with chemical and biological fertilizers on some chemical characteristics of the soil planted with sunflower plants. The vermicompost fertilizer with urea fertilizer and phosphate rock and spraying Azotobacter chroococcum bacteria gave the highest reduction in the pH of the soil (7.010), while the vermicompost fertilizer with A. chroococcum and spraying A. chroococcum bacteria recorded the highest reduction in the electrical conductivity (Ec) of the soil (1.196 ds m −1 ). The vermicompost with A. chroococcum and Bacillus sp. with spraying A. chroococcum gave the highest values in the nitrogen content of the soil, reaching 73.43 ml kg −1 , while the vermicompost and phosphate rock with spraying A. chroococcum gave the highest value in the content of phosphorus in the soil, reaching 17.86 ml kg −1 . The vermicompost fertilizer with A. chroococcum and Bacillus sp. without spraying A. chroococcum led to an increase in potassium in the soil (298.9 ml kg −1 ), whereas the vermicompost with urea fertilizer and phosphate rock with spraying A. chroococcum led to an increase in organic matter in the soil (25.88 g kg −1 ).