Topdressing accounts for approximately 40% of the total nitrogen (N) application of winter wheat on the Huang-Huai-Hai Plain in China. However, N use efficiency of topdressing is low due to the inadaptable topdressing method used by local farmers. To improve the N use efficiency of winter wheat, an optimization method for topdressing (T<sub>HP</sub>) is proposed that uses unmanned aerial vehicle (UAV)-based remote sensing to accurately acquire the growth status and an improved model for growth potential estimation and optimization of N fertilizer amount for topdressing (NFT). The method was validated and compared with three other methods by a field experiment: the conventional local farmer’s method (T<sub>LF</sub>), a nitrogen fertilization optimization algorithm (NFOA) proposed by Raun and Lukina (T<sub>RL</sub>) and a simplification introduced by Li and Zhang (T<sub>LZ</sub>). It shows that when insufficient basal fertilizer was provided, the proposed method provided as much NFT as the T<sub>LF</sub> method, i.e., 25.05% or 11.88% more than the T<sub>RL</sub> and T<sub>LZ</sub> methods and increased the yields by 4.62% or 2.27%, respectively; and when sufficient basal fertilizer was provided, the T<sub>HP</sub> method followed the T<sub>RL</sub> and T<sub>LZ</sub> methods to reduce NFT but maintained as much yield as the T<sub>LF</sub> method with a decrease of NFT by 4.20%. The results prove that T<sub>HP</sub> could enhance crop production under insufficient N preceding conditions by prescribing more fertilizer and increase nitrogen use efficiency (NUE) by lowering the fertilizer amount when enough basal fertilizer is provided.
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