High Yielding Maize Produced Negative Nitrogen Balance Despite Optimum Rate of Nitrogen Fertilizer
摘要
Maize, one of the most important and adaptable cereal crops globally, shows great potential for cultivation on fallow lands in the Ganges River delta coastal zone. However, the complete removal of stover and cobs of maize raise questions about the N fertilizer requirements to achieve yield potential and to optimize N use efficiency. Experiments on farms were conducted during the three rabi (winter) seasons of 2020, 2021, and 2023 with a wide range of N rates: 0, 45, 90, 135, 180, 225, 270, and 315 kg N ha⁻¹ on a slightly saline silty clay loam soil.In 2020, the maximum grain yield of 11.8 t ha⁻¹ was achieved at 270 kg N ha⁻¹. By comparison, maximum yields of 12.5 and 11.6 t ha⁻¹ were recorded in 2021 and 2023, respectively, at 225 kg N ha⁻¹. From a polynomial model fitted to the pooled data, 95% of the highest grain production (critical yield) required 235 kg N ha⁻¹. However, the partial N balance was highly negative at the optimal rate of N application (− 81 kg N ha− 1 ). Notwithstanding the soil salinity limitations in the eastern Ganges delta coastal region, maize grain yields of 11.8–12.5 t ha⁻¹ were achievable with 225–235 kg N ha⁻¹ as the optimal N rate. However, the implications of the negative N balance on maize yields in the medium term need to be determined.