Nutrient Use Efficiency and Environmental Implications of Fertiliser Application in Nigerian Rice Production

This study examines nutrient use efficiency and the environmental implications of fertiliser application practices in Nigerian rice production systems, addressing the growing concern about nitrogen and phosphorus losses from rice paddies to water bodies and the atmosphere. Nigeria's rice production intensification, driven by import substitution policy, has significantly increased fertiliser consumption, but nutrient use efficiency remains low, creating both economic losses for farmers and environmental risks. This study combines agronomic data from controlled field trials at research sites in Kebbi, Benue, and Anambra States with environmental monitoring of ammonia volatilisation, nitrous oxide emissions, and surface water nitrate loading adjacent to rice paddies under different fertiliser management regimes. Nitrogen use efficiency, phosphorus use efficiency, and greenhouse gas emission intensities are computed for each management treatment. Findings reveal that current average nitrogen use efficiency in Nigerian lowland rice is estimated at 28 percent, far below the global average of 42 percent. Split nitrogen application in three doses improves efficiency to 41 percent while reducing ammonia volatilisation by 48 percent. Submerged paddy soils generate significant nitrous oxide emissions under conventional fertiliser management, contributing to climate change while losing nitrogen plant nutrition value. Slow-release urea formulations show the most consistent efficiency and emission improvements. The study concludes that improving fertiliser application practices is both an agronomic efficiency and environmental imperative for Nigerian rice systems. It recommends split application adoption and slow-release urea evaluation for extension promotion.

Keywords: nutrient use efficiency, fertiliser management, rice production, nitrogen losses, environmental impact.