humic mulch

例句：

1. 1.The organic mulch helps to retain moisture in the soil.
   有机覆盖物有助于土壤保持水分。
2. 2.The humus-rich mulch improves the soil structure and fertility.
   富含腐殖质的覆盖物改善了土壤结构并提高了肥力。
3. 3. The farmers used this humic mulch to enrich the soil for their crops.
   农民们使用这种腐殖质覆盖物来为他们的作物增加土壤肥力。