Biofortification of Organic Fertilizer with Zinc-Solubilizing Bacteria to Enhance Grain Yield, Inorganic Fertilizer Efficiency, and Zinc Content of Sorghum
Description
Organic fertilizer quality biofortified with ZSB and its impact, in combination with Nitrogen, Phosphorous, and Potassium (NPK) fertilizer, on the growth of sorghum, grain yield, soil Zn availability, grain Zn content, and NPK fertilizer efficiency.
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The viability of the enrichment bacteria population in organic fertilizer was observed at regular intervals over six months to ascertain the survival capacity of the bacteria. The cow dung's organic material was composted using ZSB consortia formulas, ZSB A and ZSB B. The flow chart outlining the preparation of organic fertilizer enriched with ZSB and its subsequent application in greenhouse and field trials. ZSB A formula consisted of a consortium of bacteria: Klebsiella pneumoniae Zn2, K. quasipneumoniae CmA9, Enterobacter cloacae CmA12, Providencia rettgeri DrSrA1, and K. aerogenes B1-52, which were known to be ZSB. Meanwhile, ZSB B contained a consortium of bacteria K. pneumoniae Zn2, K. quasipneumoniae CmA9, P. rettgeri DrSrA1, Azotobacter vinelandii 1CM, and Bacillus subtilis P18.3. Previous studies had shown that K. pneumoniae Zn2, K. quasipneumoniae CmA9, and P. rettgeri DrSrA1 were ZSB, while A. vinelandii 1CM and B. subtilis P18.3 were N2-fixing and P-solubilizing bacteria, respectively. All ZSB in this study were confirmed to exhibit cellulolytic activity. The preparation of organic fertilizer fortified with ZSB comprised air-drying the organic fertilizer, followed by grinding and shifting to a diameter of 2 mm. Subsequently, the samples were mixed with ZSB until homogeneity was achieved. Chemical quality tested for organic fertilizers included analyzing various parameters, such as pH, water content, organic C, ratio C/N, macronutrients (N + P₂O₅ + K₂O), micronutrients (total Fe, available Fe, and Zn), bacteria pathogens (E. coli and Salmonella sp.), metal content (Hg, Pb, Cd, As, Cr, and Ni), and the number of functional bacteria (Klebsiella sp., Providencia sp., Enterobacter sp., Azotobacter sp., and Bacillus sp.), phytohormones (Indole Acetic Acid, Gibberellin, Zeatin, and Kinetin), and organic acids. The enrichment bacterial populations were determined using the Total Plate Count method on Pikovskaya solid media enriched with ZnO. The volume of microbial liquid inoculant sprayed was contingent upon the desired final population in the organic fertilizer. The number of functional bacterial populations in solid organic fertilizer fortified with ZSB met the minimum technical requirements of more than 105 colony-forming units (CFU) per gram (g).
Institutions
- Badan Riset dan Inovasi Nasional Republik Indonesia