Comparison of organic and conventional farming for onion yield, biochemical quality, soil organic carbon, and microbial population

<p>In an ongoing field experiment, organic and conventional farming (control) were compared for onion bulb yield, biochemical quality, soil organic carbon (SOC), and microbial activity after the sixth cropping cycle. The treatments used for organic production were farmyard manure (FYM, 20,000 kg ha⁻¹), poultry manure (PM, 10,000 kg ha⁻¹), vermicompost (VC, 10,000 kg ha⁻¹), neem cake (NC, 5000 kg ha⁻¹), and a combination of FYM (5000 kg ha⁻¹), PM (2500 kg ha⁻¹), VC (2500 kg ha⁻¹), and NC (1250 kg ha⁻¹); all treatments were compared with the control. Organic treatments produced 24.6–43.6% lower yield consistently for 6 years than the control treatment. No significant difference was observed between PM, FYM, and VC treatments for the bulb yield. Bulb analysis during the sixth year indicated that plants that received FYM, PM, or VC had higher levels of total phenol, total flavonoid, ascorbic acid, and quercetin-3-glucoside than the control plants. All the five organically treated sets had significantly higher values of SOC, microbial population, fungal-to-bacterial ratio, and dehydrogenase activity than the control and the initial values in each treated set. The results indicate that FYM, PM, or VC application enhances biochemical quality and organic farming is more sustainable than conventional farming.