Effect of biofertilizers with various levels of inorganic nutrients on growth and yield of black cumin (Nigella sativa L.) var. Azad Kalonji

The objective of the study is to reduce the amount of inorganic fertilizers by using biofertilizers with the aim of sustainable agriculture. The field experiment was conducted at the HRS, Mondouri, BCKV, West Bengal, India during rabi season of 2019-20. The experiment consisted of 14 treatments replicated thrice, comprising of three levels inorganic fertilizers (50, 75 and 100%) of recommended NPK and three biofertilizers viz. Azospirillum lipoferum (N fixer), Bacillus megaterium (potash mobilizer) and Fraturia aurantia (K mobilizer) as soil application. The results indicated that the maximum plant height (86.06 cm) at 100 DAS, number of primary (10.66) and secondary branches (17.33), number of capsules plant-1 (25.33), number of seeds capsule-1 (97.66), test weight (3.54 g) and projected yield (538.50 kg ha-1) were recorded in 100% RDF + Azospirillum + PSB + KS. The yield was at par with 75% RDF + Azospirillum + PSB + KS (536.74 kg ha-1). Considering the economics, maximum net return (Rs. 1,08,083.74 ha-1) and B: C ratio (4.14: 1) was obtained from 75% RDF + Azospirillum + PSB + KS. These results suggested that combination of Azospirillum + PSB + KS with 75% RDF was best for optimum production of black cumin without loss in yield and reduction of 25% of inorganic fertilizers through application of biofertilizers and environmental pollution to some extent.