肥沃

1. Origins, structure, and basic meaning

• Structure: 肥沃 (ひよく) is a na-adjectival expression for soil rich enough in nutrients to support strong plant growth.
• Basic usage: 肥沃な土地が広がる attributes fertility to riverside soil, while 土を肥沃にする marks the result of fallen leaves enriching the ground.

2. Common pitfalls and similar expressions

• Soil property and induced change
  • 肥沃な土地 is an existing property, whereas 肥沃にする has another factor create that state. The expression does not merely mean wet or extensive land.