Effects of N and NPS Fertilizer on Yield Components and Seed Yield of Black Cumin (Nigella Sativa L.) at Bale, South eastern Ethiopia

Black cumin is one of the most widely grown seed spices crops in the highlands and mid altitude of Bale. However, the productivity is low due to poor agronomic practices, diseases, insect pests and other botic and abiotic factors. Therefore, an on-farm experiment was conducted to determine the effects of N and NPS fertilizer rates on yield components and yield of black cumin and to recommend the most economically feasible rate of N and NPS fertilizer for black cumin production. Analysis of variance indicated that days to flowering, days to physiological maturity, number of secondary branches per plant, number of capsule per plant and number of seed per capsule were significantly affected by N and NPS fertilizer while plant height and seed yield were significantly affected by the interaction of N and NPS fertilizers. Increasing nitrogen fertilizer from 0 N kg ha–1 to 90 N kg ha–1 and NPS fertilizer from 0 NPS kg ha–1 to 105 NPS kg ha–1 were decreased days to 50% flowering whereas; increasing nitrogen fertilizer from 0 N kg ha-1 to 90 N kg ha–1 and NPS fertilizer from 0 NPS kg ha–1 to 105 NPS kg ha–1 prolonged the duration to reach physiological maturity. The maximum plant height (79.93 cm) was obtained from 90 N kg ha-1and 70 kg NPS ha-1which is statistically at par with 90 N and 105 kg NPS ha-1. The highest number of capsule per plant (9.583) was obtained from 90 kg N ha-1which is statistically at par with 60 kg N ha-1. The highest number of seed per capsule was produced in response to the application of 60 and 90 N Kg ha–1.The crop attained its highest seed yield (1669 kg ha-1) at the application rates of 60 kg N and 70 kg NPS ha–1. The economic analysis also indicated that the highest net benefit/return with highest marginal rate of return was gained from application of 60 N kg ha-1 and 70 Kg NPS ha-1. Therefore, based on the results of the yield, yield parameters and Partial Budget Analysis, the application of 60 N Kg ha-1and 70 NPS kg ha-1 can be recommended for black cumin production for area known by producing this crop.