Sustainable Rice Fertilization: Can Nano-Urea and Nano-Diammonium Phosphate Reduce Nitrogen and Phosphorus Inputs without Yield Penalties in Bangladesh?

Abstract

Efficient fertilizer management is essential for sustaining rice productivity in Bangladesh while lowering production costs and minimizing environmental risks. This study examined whether liquid nano-urea (LNU) and liquid nano-diammonium phosphate (LND) could partially replace conventional prilled urea and diammonium phosphate (DAP) without yield penalties. Field experiments were conducted across six agro-ecological zones during the Boro 2022–23 and 2023–24 seasons, using randomized complete block designs with three replications. In the LNU experiment, various N rates and foliar sprays of nano-formulations were tested, whereas in the LND experiment, different P rates and foliar sprays of nano-formulations were evaluated. In 2022–23 at Gazipur, applying 66% of the recommended dose of prilled urea (RDPU) plus foliar LNU achieved yields (6.55 t ha⁻¹) statistically comparable to 100% RDPU (7.00 t ha^-1), saving 34% of urea. Multi-location trials in 2023–24 confirmed that yields from 66% RDPU with LNU often matched those from 100% RDPU, particularly in Gazipur, Cumilla, Habiganj, and Rajshahi. In Habiganj, two foliar sprays of LNU with 50% RDPU produced yields equivalent to those of 66% RDPU alone, indicating a potential to save 16% of urea. No significant yield differences were observed among LND treatments, and plots without phosphorus fertilization yielded similarly to those with 100% recommended P. This suggests that residual soil P supported crop growth during a single season, although long-term P omission could risk soil depletion. Overall, nano-urea enabled yield maintenance with up to one-third lower urea inputs, reducing input dependency and supporting national food security goals. Strategic use of 50% recommended P, with or without nano-DAP, may offer a sustainable pathway for phosphorus management in rice systems. However, long-term soil health impacts, economic feasibility, and farmer adoption dynamics require further investigation before large-scale recommendations can be made.

Bangladesh Rice J.29(1): 44-52, 2025