Effect of proportional substitution of potassic fertilizer with biofertilizers in onion

A fundamental shift has taken place in agricultural research and world food production. Today, the drivefor productivity is increasingly combined with a desire for sustainability. A field experiment was carried out insandy loam soil during kharif 2016-17 with kharif onion cv. Agrifound Dark Red using Azolla and vermicompostfor sustainable crop production. The experiment comprised of 8 treatments, T₁ (no K application), T₂ (50 per cent RDK), T₃ (100 per cent RDK), T₄ (50 per cent RDK + 50 per cent K by Azolla), T₅ (50 per cent RDK + 50 per cent K by Vermicompost), T₆ (50 per cent RDK + 25 per cent K by Azolla + 25 per cent K by Vermicompost), T₇ (100 per cent K by Azolla) and T₈ (100 per cent K by Vermicompost). Full dose of N and P were applied in all thetreatments through urea and SSP, respectively. However, potassium was supplied through muriate of potash(MOP) having 60 per cent K₂O, vermicompost (0.8 per cent potassium) and Azolla (2.62 per cent potassium on dry wt. basis). Results from field experiment showed that treatment T₇ was found significantly superior overall other treatments to increase plant height of onion at 90 (45.59 cm) and 120 DAT (50.80 cm) and the lowestplant height was recorded in control (T₁). Dry matter content (14.34 g plant⁻¹) was found to be the highest with treatment T₅ at 120 DAT. However, treatment T₄ resulted highest dry matter 0.513, 1.52, 5.54 g plant⁻¹ at 30, 60 and 90 DAT respectively. Equatorial (55.86 mm) and polar (47.59 mm) diameters of onion bulbs were found tobe significantly higher with treatment T₅. The highest bulb weight (45.17 g) and yield of onion (13.17 t ha⁻¹) wererecorded with treatment T₅ which was 16.24 and 41.46 per cent higher bulb yield as compared to that recorded with T₃ and T₁ respectively. However, the lowest bulb weight (35.10 g) and bulb yield (9.31t ha⁻¹) were recordedin the plots receiving no potassium. Calculation of cost of production and benefit obtained showed that thetreatment T₃ gave maximum benefit: cost ratio of 2.1. However, B: C ratio of T₄ and T₅ was 1.9 and 1.6, respectively.