224 Introduction Nigella (Nigella sativa L.) is a minor and annual herbaceous seed spice crop belonging to the family Ranunculaceae. It is widely cultivated throughout Southern Europe, Syria, Egypt, Saudi Arabia, Iran, Pakistan, India and Turkey (Riaz 1996). The seeds are known as black cumin. Mature seeds are consumed for edible and medical purposes. The seeds are also used in seasoning of vegetables, legumes and different type of baked products. Recent pharmacological investigations have proved the potential therapeutic effects of nigella seed as well as its oil through various studies. Precise information on weed management in nigella is essential and inevitable for getting healthy growth of plants. Being a slow growing seed spice, more prone to crop weed competition. Initial slow growth of nigella leads to severe weed crop competition and reduces growth as well as yield by as high as 91.4% (Mali & Suwalka 1987). Manual weeding is commonly employed practice. But availability of labour is a problem, besides its high cost. Economic feasibility of weed management practices in nigella ( Nigella sativa L.) S S Meena*, R S Mehta, R D Meena, R L Meena & D K Sharma National Research Centre on Seed Spices, Tabiji, Ajmer-305 206, Rajasthan. *E-mail: ssmnrcss5@yahoo.com Received 14 May 2013; Revised 06 September 2013; Accepted 20 March 2014 Abstract A field experiment was conducted to find out the suitable and economical method of weed control in nigella. Based on two year study, it was found that besides weed free treatment, significantly higher plant height, number of primary and secondary branches, number of leaves, number of nodes and dry matter accumulation plant -1 (at 60 days after sowing (DAS), 90 DAS and at harvest) were recorded with the pre-emergence application of oxadiargyl @ 75 g ha -1 + one hand weeding at 45 DAS and pendimethalin @ 1 kg ha -1 + one hand weeding at 45 DAS. Similarly, yield attributes like number of siliqua plant -1 , number of seeds siliqua -1 , siliqua size and test weight as well as seed and straw yields of nigella were also higher with these two treatments. Besides weed free treatment, lower dry weight of weed at harvest, weed index with highest weed control efficiency was obtained under pre- emergence (PE) application of oxadiargyl @ 75 g ha -1 + one hand weeding at 45 DAS. The Highest gross returns and net returns were obtained in weed free treatment followed by effective control of weed with pre -emergence application of oxadiargyl @ 75 g ha -1 + one hand weeding at 45 DAS but highest B: C ratio (2.62) was recorded with pre- emergence application of oxadiargyl @ 75 g ha -1 + one hand weeding at 45 DAS. Keywords: economics, herbicides, nigella, seed yield, weed, weed index Journal of Spices and Aromatic Crops Vol. 23 (2) : 224–228 (2014) Indian Society for Spices www.indianspicesociety.in/josac/index.php/josac