Development of Organically Complexed-Bioaugmented Boron-Coated DAP and Its Effect on Yield and Quality of Canola (Brassica napus L.)

Many agricultural soils fail to supply sufficient boron (B) and phosphorus (P) to growing plants due to their adsorption, precipitation and fixation phenomena. Moreover, the application of individual B sources without a macronutrient fertilizer is impractical owing to the separate handling and poor distribution in the field. The study aimed to develop and compare the efficiency of organically complexed boron-diammonium phosphate (B-DAP) formulations with commercial diammonium phosphate (C-DAP) and boric acid for improving yield and oil content of canola. To prepare 0.5, 1 and 1.5% B-DAP formulations, PGPR-impregnated pressmud containing 1% B (slurry) was coated on C-DAP to achieve slurry to P2O5 ratio as 0.5:1, 1:1 and 1.5:1, respectively. Treatments tested in incubation, pot and field studies were C-DAP130, C-DAP130 + B2.5, and 0.5%, 1% and 1.5% B-DAP; each B-DAP formulation was added to supply 98 and 130 kg P2O5 ha−1. The results of the incubation study depicted that with the application of 1.5% B-DAP130 available P content increased by 51% between 2 and 10 weeks of incubation. Likewise, soils fertilized with B-DAP98 and B-DAP130 had significantly (p < 0.05) higher hot-water extractable B content up to 10th week of incubation. In case of pot and field experiments, 1.5% B-DAP98 was found the most effective for canola as it produced the maximum grain yield under field conditions with 38% escalation compared to C-DAP130 and 16% increase compared to C-DAP130 + B2.5. The application of 1.5% B-DAP98 showed maximum oil content of 48 and 42% under pot and field conditions, respectively. It is concluded that the application of 1.5% B-DAP98 enhanced the canola yield, nutrient uptake and oil content more than C-DAP130 + B2.5.