Maize Genomics and Genetics 2025, Vol.16, No.5, 258-266 http://cropscipublisher.com/index.php/mgg 260 (Du et al., 2021). Some studies have found that if the density is appropriately increased and the amount of nitrogen fertilizer is reduced, the utilization efficiency of nitrogen fertilizer can be improved, and the yield will not necessarily decrease, and may even increase (Shi et al., 2016). Different maize varieties are also quite different. Some varieties are naturally suitable for high-density planting, such as hybrids with compact plant shapes and suitable maturity periods (Ye et al., 2023). In addition, climatic conditions such as precipitation, soil fertility, and latitude will also affect the effect of planting density on yield. Therefore, the best way is to determine the density and management method based on local actual conditions. 3 Fertilization Strategies for Optimized Yield 3.1 Nitrogen management and maize productivity If you want to increase maize production without wasting fertilizer or polluting the environment, nitrogen fertilizer must be used appropriately. Generally speaking, if nitrogen fertilizer is used at about 180 to 200 kg per hectare, the yield is very good, and the effect is similar to high nitrogen application, but the damage to the environment will be much less, for example, nitrates are not easily lost, and there is less residue in the soil (Yang et al., 2017). If nitrogen fertilizer is applied deeper, such as about 25 cm, it can be more absorbed by maize, which is also conducive to dry matter accumulation and yield increase. This method will be more effective if combined with appropriate planting methods (Zheng et al., 2023; Tian et al., 2024). In some places, maize needs to absorb a lot of nitrogen after silking. In this case, applying some nitrogen fertilizer in the later stage may help increase yield. But whether it works depends on the local climate and soil conditions (Fernández et al., 2020). On the contrary, applying too much nitrogen fertilizer not only does not help with yield, but also brings some negative effects, such as wasting fertilizer, polluting water sources, and is bad for the environment (Medina-Cuéllar et al., 2021). 3.2 Role of phosphorus, potassium, and micronutrients In addition to nitrogen fertilizer, phosphorus (P), potassium (K) and some trace elements are also very important. If you want to grow high-yield maize, these fertilizers are also indispensable. Using nitrogen, phosphorus and potassium together, especially with organic fertilizers, can not only increase yields, but also improve soil and increase water use efficiency (Abdo et al., 2022). In addition, if organic fertilizers or biofertilizers are used to replace part of chemical fertilizers, especially when applied together with natural stimulants such as humic acid and amino acids, the yield will not only not decrease, but may be more stable. It can also reduce dependence on chemical fertilizers and reduce environmental pollution (Jiang et al., 2024). 3.3 Site-specific and precision fertilization approaches The soil, weather, and crop requirements in different places are different, so fertilization cannot be a one-size-fits-all approach. It would be more reasonable to adjust the amount and depth of fertilization according to local actual conditions. For example, according to the different growth periods of maize, combined with weather and soil conditions, deep fertilization and irrigation fertilization can allow maize to absorb better, increase yields, and save costs (Xu et al., 2020; Yan et al., 2021). Using chemical fertilizers and organic fertilizers together, and then using some data-based methods to arrange fertilization time and amount according to the actual needs of crops, can more effectively support the continued high yield of maize (Zhai et al., 2022). 4 Combined Effects of Plant Density and Fertilization 4.1 Yield response under varying combinations Studies have found that appropriately increasing the planting density and reducing the amount of nitrogen fertilizer can simultaneously increase maize yield and fertilizer utilization efficiency (Figure 2). For example, planting 30% more maize than traditional practices and reducing nitrogen fertilizer by 15% to 30% can increase yield by 6% to 13%, and the efficiency of nitrogen fertilizer use is also higher (Du et al., 2021). This approach is particularly suitable for years with normal water volume or sufficient water sources. It can also be used in semi-arid areas or places with irrigation. However, whether the density is too high or too much nitrogen fertilizer is used, it may eventually lead to a mediocre yield or even a decrease in yield. Therefore, the two must be properly matched, not just more or less (Lai et al., 2022).
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