synthetic humic acids

例句：

1. 1. The synthetic humic acids are widely used in agriculture to improve soil fertility.
   合成腐殖酸在农业中被广泛使用，以提高土壤肥力。
2. 2. These synthetic humic acids have been shown to enhance plant growth and reduce nutrient loss.
   这些合成腐殖酸已被证明能促进植物生长并减少养分流失。
3. 3. In recent years, there has been a growing interest in using synthetic humic acids as a natural fertilizer alternative.
   近年来，人们越来越关注使用合成腐殖酸作为天然肥料的替代品。