Physiological Indices, Productivity and Profitability Assessment at Varying Nitrogen Levels of Wheat Under Conservation Agriculture.

Conservation agriculture (CA) is a promising management practice adopted by spring wheat growers in the Indo-Gangetic plains (IGPs) of India, particularly in areas where residue burning is prominent. Effective nitrogen management is essential to achieve maximum profitable wheat yield under CA to promote agricultural sustainability. A field experiment conducted during the winter seasons of 2020–21 and 2021–22 comprising seven treatments with varying nitrogen doses from 0 to 250 kg/ha was used to find the best nitrogen management strategy. Instrument-based physiological indices, including the chlorophyll content index (CCI), normalized difference vegetation index (NDVI), Dualex meter-based values, and flavonoids, were used to investigate the relation between these indices and growth stages. Increasing nitrogen levels from 0 to 250 kg/ha resulted in increased growth and physiological indices. However, the increase beyond 150 with or without CA was non-significant in case of many indices. The enriched treatment (250 kg N/ha) recorded a lower grain yield (5123 kg/ha) compared to 100 kg N/ha treatments (5595 kg/ha). The thousand-grain weight was also found to be reduced by 21.2% in 250 kg N/ha compared to the 150 kg N/ha treatment. The application of 200 kg N/ha under CA produced a significant increase (9.6%) in grain yield (6673 kg/ha) as compared to the farmer's practice of 150 kg N/ha. Applying 150 kg N/ha under CA increased grain yield by 231 kg/ha over the same N level without CA, although the difference was non-significant. The application of 200 kg N/ha under CA yielded the highest gross return (2271.8 $/ha), net return (1545.0 $/ha), and B:C (3.1) due to the reduced cost of cultivation in CA and maximum grain yield. Additionally, if this technology is adapted to 13.7 m ha rice–wheat area in South Asia then additional net return from 200 kg N/ha application under CA over farmers practice will be $3.32 billion annually, which is huge amount. Therefore, using 200 kg N/ha under CA can further increase grain yield, productivity, and profitability per unit area. However, for resource-limited growers in rice–wheat growing areas, 150 kg N/ha under CA can still be a viable and economically sound option. [ABSTRACT FROM AUTHOR]