EFFECT OF NITROGEN SOURCE AND APPLICATION SCHEDULE ON PRODUCTIVITY AND PROFITABILITY OF BLACK CUMIN (NIGELLA SATIVA L.)

Abstract

Efficient nitrogen (N) management through its appropriate source and timing of application is essential for enhancing crop yield. A field study was conducted during the winter growing seasons 2021–22 and 2022–23 at Agronomic Research Station, Khanewal, Punjab-Pakistan to most suitable source and application time of N on growth and yield of black cumin. Ammonium sulfate, ammonium nitrate and urea were used as different N sources and whole N application at sowing, 1/2 N at sowing + 1/2 N at branching, 1/3 N at sowing + 1/3 at branching + 1/3 at f lowering as varable N application timings. Results showed that ammonium sulfate consistently outperformed all other N sources. Relative to urea, ammonium sulfate increased plant height by 18% and 4%, branches per plant by 33% and 25% during 2021–22 and 2022–23, respectively. The number of capsules per plant improved by 8% and 7% in the respective years. Likewise, ammonium sulfate increased the number of seeds per capsule by 12% and 5% and boosted seed yield by 7% and 9% across the two years. Among N split-application treatments, the three-split application of 18.3 kg N ha⁻¹ at sowing, branching and flowering proved the most effective. Compared with the control, said treatment increased plant height by 90% and 18% during 2021–22 and 2022–23, respectively. The number of branches per plant improved by 150% and 57%, while the number of capsules per plant increased by 17% and 33% across the two years. Similarly, said treatment enhanced the number of seeds per capsule by 94% and 16%, and increased 1000-seed weight by 84% and 53% in the respective years. Seed yield was also substantially higher, with gains of 67% and 50% over the control. A significant interaction between N source and N split-application was observed. Among all combinations, ammonium sulfate applied in three splits produced the highest values. Compared with the lowest-performing combination; urea with no N application (control); this treatment increased plant height by 114% and 23% in 2021–22 and 2022–23, respectively. The number of branches per plant increased by 200% and 67%, while the number of capsules per plant improved by 22% and 44% across the two years. Thousand-seed weight was enhanced by 112% and 49%, and seed yield was boosted by 70% and 68%, respectively. Economic analysis revealed that ammonium sulfate applied in three splits gave the highest net income (Rs. 301044 and 301044 during 2021-22 and 2022-23 respectively) and benefit-cost ratio (2.41 and 1.99) during respective years. It is concluded that the application of ammonium sulfate in three equal splits at sowing, branching, and flowering is the most effective N management strategy for black cumin.