Optimizing Variety and Sowing Date for Mustard-Boro Rice-fallow Cropping Pattern under Contrasting Land Elevations in the Haor Areas of Kishoreganj, Bangladesh

The Haor areas of northeastern Bangladesh are characterized by unique hydro-ecological conditions, significant agricultural potential, and challenges such as recurrent flash floods and low cropping intensity. While previous studies have examined mustard and Boro rice performance in isolation, the combined Mustard–Boro rice cropping pattern under varying sowing dates and land elevations remains underexplored. To address this gap, a field experiment was conducted during the 2022–23 and 2023–24 Boro seasons in Austagram village, Kishoreganj district. The study employed a split-split-plot design with three factors: land elevation, sowing date, and variety, replicated three times. The findings revealed that medium-high land and early sowing significantly reduced maturity and field duration while enhancing yield components and overall productivity for both crops. Rice cultivated on medium-high land produced 4.5% more grain yield (p<0.001), and early sowing increased yield by 4% compared to late sowing (p<0.001). Among rice varieties, BRRI dhan84 and BRRI dhan88 consistently outperformed others, achieving up to 26.34% higher grain yield in 2022–23 (p<0.001) and 11.11% in 2023–24 compared to BRRI dhan89 (p<0.01). Similarly, BARI Sarisha-14 exhibited the highest mustard yield, with a 56% increase in 2022–23 and 43% in 2023–24 over Tori-7 (p<0.001). These results suggest that adopting BRRI dhan84, BRRI dhan88, and BARI Sarisha-14, combined with medium-high land cultivation and early sowing, can enhance cropping intensity, avoid the risks of flash floods, and promote sustainable agriculture in the Haor regions, thereby improving the socio-economic conditions of farmers.