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Yield of maize under different nitrogen fertilizer application rates. 0 kg·ha-1(N0); 120 kg·ha-1(N8); 180 kg·ha-1(N12); 240 kg·ha-1(N16); 300 kg·ha-1(N20); 360 kg·ha-1(N24). The distinct lowercase letters indicate statistically significant differences at the 0.05 significance level.
