Maximizing productivity in onion bulb cultivation through crop geometry and NPKS nutrient management

Abstract: A study was conducted to determine the optimal dosage of NPKS fertilizer and the most suitable crop geometry to enhance both productivity and bulb quality of kharif onion (Allium cepa L.). The research was laidout using a split plot design, incorporating three levels of NPKS fertilizer in the main plot and five different crop geometries in the subplot, with three replications spanning from August to November in the years 2020-21 and 2021-22. Among the various combinations tested, the widest crop geometry (15 cm x 15 cm) coupled with the application of 140 N: 80 P: 80 K: 40 S kg ha^-1 dose of nutrients exhibited superior results. This combination resulted in the highest values for plant height (97.88 cm), number of leaves per plant (19), leaves’ weight per plant (74.15 g), average bulb weight (133.97 g), and harvest index (51.24). Conversely, the closest spacing (7.5 x 7.5 cm) with the highest fertilizer dose led to the maximum biological yield (125.89 t ha^-1) and bulb yield (61.89 t ha^-1). Notably, the spacing of 10 x 10 cm with the application of 140 N: 80 P: 80 K: 40 S kg ha^-1 emerged as the optimal combination for achieving the highest marketable yield (43.62 t ha^-1), gross return (? 5.23 lakhs), net return (? 4.23 lakhs), and benefit-cost ratio (4.23). Consequently, we conclude that, for maximizing the production of marketable bulbs of kharif onion, a crop geometry of 10 x 10 cm with a nutrient dose of 140 N: 80 P: 80 K: 40 S kg ha^-1 is recommended. This information contributes valuable insights for optimizing onion cultivation practices, thereby enhancing both yield and economic returns.