Effect of FYM and Bio-fertilizers on Growth, Yield, Quality and Economics of Potato-Onion Cropping Sequence under Drip Irrigation

Abstract

Potato–onion cropping systems require efficient nutrient and water management to sustain productivity, crop quality, and economic returns. Continuous nutrient removal by both crops can reduce soil fertility when appropriate nutrient replenishment is not maintained. The integrated use of farmyard manure (FYM) and bio-fertilisers under drip irrigation may improve nutrient availability, crop performance, and resource-use efficiency. However, information on their combined direct and carry-over effects in a sequential potato–onion cropping system remains limited. A field experiment conducted during 2020–21 evaluated the effect of integrated nutrient management, specifically farmyard manure (FYM) and bio-fertilisers (Azotobacter + Pseudomonas), on productivity, crop quality, soil health, and overall system profitability in a potato–onion cropping sequence under drip irrigation in semi-arid conditions. Applying 20 t ha⁻¹ FYM to both crops, together with bio-fertiliser inoculation, yielded the best performance across the evaluated parameters. This integrated treatment achieved the highest system productivity, with a potato tuber yield of 250.43 q ha⁻¹, an onion bulb yield of 260.67 q ha⁻¹, and a combined Potato Equivalent Yield (PEY) of 597.98 q ha⁻¹. In addition to increasing physical yields, the organic and bio-fertiliser combination significantly enhanced quality attributes, increasing potato starch content to 14.48%, while onion total soluble solids reached 7.2 °Brix and total phenolic content reached 48.64 mg g⁻¹ GAE. Economic evaluation further demonstrated the financial viability of this approach, as the treatment generated the highest net returns and recorded benefit–cost (B:C) ratios of 2.02 for potato and 2.40 for onion. Overall, combining drip irrigation with targeted organic amendments and bio-fertiliser inoculants provided a high-yielding and economically viable management option for the intensive vegetable cropping system evaluated in this study.