Using GreenSeeker active optical sensor for optimizing maize nitrogen fertilization in calcareous soils of Egypt

Sensor-based strategies for nitrogen (N) management are promising to achieve high N fertilizer use efficiency and to reduce the amount of wasted N reaching the environment. A need-based N management strategy using an active optical sensor was evaluated for maize grown in a calcareous soil, western of Nile Delta, Egypt. Field experiments were conducted at two locations during 2015 and 2016 to develop and validate an algorithm for refining N fertilizer application. An increasing rate of N fertilizer was applied in the experiment conducted in 2015year at two different locations to establish plots with different yield potentials. The experiment conducted in 2016year aimed at validating the established sensor algorithms. It was demonstrated that growth stage V9 (9(th) leaf collar fully unfolded) is the appropriate stage for applying a corrective N fertilizer dose. Application of a prescriptive dose of 150kg N ha(-1) in two equal split doses, followed by a corrective dose guided by the optical sensor resulted in similar yield as general recommendation, but with lower total fertilizer application. This study revealed that N fertilizer in maize could be managed more efficiently using sensor-guided management than the current general recommendation in calcareous soils of Egypt.