noun, noun which may take the genitive case particle 'no'
suitably damp; adequately wet
Often used in horticultural or agricultural contexts to describe soil or growing conditions that are moist enough for plants.
この植物は適潤な土壌を好む。
This plant prefers suitably damp soil.
適潤の状態を保つために、定期的に水をやる必要がある。
To maintain an adequately wet condition, you need to water it regularly.