Effects of Nitrogen Fertilizer Topdressing on Nitrogen Utilization, Yield, and Quality of Early Maturing Maize Intercropping with Tobacco

Purpose To alleviate the effects of field environment with low temperature and insufficient light on early-maturing corn in the flue-cured tobacco intercropping system.

Methods The experiment was conducted using the tobacco variety Yunyan87 and the maize variety Jingengzao No.8 as materials. Based on the same amount of basal fertilizer, six different nitrogen fertilizer (urea) application treatments were set: 0 kg/hm² (T₁), 150 kg/hm² (T₂), 300 kg/hm² (T₃), 450 kg/hm² (T₄), 600 kg/hm² (T₅), 750 kg/hm² (T₆), which were applied in two topdressing stages (60% at seedling stage, 40% at big trumpet stage); in addition, no fertilization treatment (T₀) was set. The experiment was used to study the effects of different nitrogen application amounts on the nitrogen utilization and yield quality of intercropping maize.

Results Compared with the T₀ treatment, increasing the nitrogen application amount to 300 kg/hm² could significantly improve the soil nitrogen content, nitrogen use efficiency, and yield of maize intercropped with flue-cured tobacco(P<0.05). At the mature stage of maize, the soil nitrogen content under T₃ treatment was significantly higher than that under T₀ and T₁ treatments (P<0.05), but there was no significant difference compared with T₄-T₆ treatments (P>0.05). The agronomic efficiency and apparent nitrogen utilization rates of T₃ treatment were significantly higher than those of T₁ and T₂ treatments (P<0.05), and the nitrogen harvest index was 22.57%-54.95% higher than that of T₀, T₁, T₂, and T₆ treatments. Compared with T₀ and T₂ treatments, the maize yield of T₃ treatment was significantly increased by 38.83%-201.73% (P<0.05); compared with T₀ treatment, the contents of crude protein, crude fat, and starch of T₃ treatment were increased by 81.06%, 59.65%, and 44.19%, respectively.

Conclusion Under the conditions of this experiment, the nitrogen utilization rate, yield, and quality of maize are the best when applies 300 kg/hm² urea. This is of great significance for increasing the yield of corn intercropped in tobacco fields and promoting the coordinated development of grain and economy.