Influence of biofertilizers on Microbial Count and Nutrient uptake of kharif onion (Allium cepa L.)

The experiment comprised of fifteen combinations of biofertilizers, organic manures and chemical fertilizers was conducted in RBD replicated thrice. The biofertilizers improved the microbial content and nutrient uptake of onion stover as compared to control and recommended chemical fertilizers. Highest Bulb dry mass (45.7 q/ha) and stover dry mass (27.9 q/ha) was observed in Azospirillum along with recommended fertilizer dose (T₃) followed by Azotobacter along with recommended fertilizer dose (T₁). Application of Azospirillum along with recommended fertilizer dose (T₃) resulted in significantly higher nitrogen uptake (210.3 Kg ha⁻¹) over all the treatments except Azotobacter along with recommended fertilizer dose (T₁). The highest phosphorus uptake (21.5 Kg ha⁻¹) was attained with application of Azotobacter along with Vesicular-Arbuscular Mycorrhizae and recommended fertilizer dose (T₉) over all the treatments. Organic manures improved the organic carbon status of soil and highest organic carbon of soil was observed in treatment where FYM @ 20 t/ha (T₁₂) and FYM @ 20 t/ha along with Azotobacter and Vesicular-Arbuscular Mycorrhizae (0.4%) was applied. While, highest bacteria (27.2 × 10⁶) and actinomyctes (34.0 × 10⁴) count was observed in FYM @ 20 t/ha treatment (T₁₂). Azotobacter along with recommended fertilizer dose (28.2 × 10³) had highest fungal count at the time of harvesting. The present study highlights the need of use of biofertilizers along with organic and inorganic manures/fertilizer to enhance the nutrient availability and improve soil health.