secondary magnesium

例句：

1. 1.The secondary magnesium content in the soil is crucial for plant growth.
   土壤中的次要镁含量对植物生长至关重要。
2. 2.The research on secondary magnesium has shown promising results.
   关于次级镁的研究取得了令人鼓舞的成果。
3. 3. The use of secondary magnesium in agriculture can improve soil fertility and reduce environmental pollution.
   农业中使用次级镁可以提高土壤肥力并减少环境污染。