Investigating the effect of Aspergillus niger inoculated press mud (biofertilizer) on the potential of enhancing maize (Zea mays. L) yield, potassium use efficiency and potassium agronomic efficiency

Globally field application of mineral potassium (K) fertilizer has grown, followed by reduced K use efficiency (KUE) and K agronomic efficiency (KAE) which ultimately leads to environmental pollution and economic loss. The soils of Pakistan have a low K level due to a higher proportion is present in an unavailable form. The objective of the current study was to isolate efficient plant growth-promoting fungus to sustainably manage huge burden of sugar industry waste press mud into a productive biofertilizer. K from biofertilizer was then evaluated in different treatments for maize biological yield, grain yield, harvest index (HI), K uptake in different maize parts, KUE and KAE in comparison to mineral fertilizer (MF). The efficiency of treatment was measured on higher KUE and KAE. In-vitro studies revealed that A. niger PM-4 was found to solubilize phosphate (389 ug/ml) and zinc (115 ug/ml) from insoluble tri-calcium phosphate and zinc oxide, respectively, at a wider temperature and pH range. The strain was also found to inhibit the production of aflatoxins and its inoculation into press mud produced non-phytotoxic and mature biofertilizer with germination index 96.5%. Bio-augmentation of press mud with A. niger shortens maturity period with improved nutrient contents. Higher grain yield and harvest index of maize were achieved with a higher amount of incorporated K from mineral and biofertilizer T5((100%Org+50%MF)) than any other treatment. However, higher KUE and KAE were found in the following order: T6 > T5 > T2 > T3 > T4 > T1, demonstrating the integrated and balanced use of K from mineral and biofertilizer without threatening the environment.

Automated summary

The global application of mineral potassium fertilizer is increasing, but the efficiency of potassium use is decreasing, leading to environmental pollution and economic losses. Pakistan's soil has a low potassium level, prompting research into efficient plant growth-promoting fungus to manage waste and evaluate the impact of different treatments on crop yield and potassium use efficiency.