腐植 is read as ふしょく (fushoku) and means humus.
ふしょく
fushoku
ふせいしょくぶつ
saprophytic plant
ふしょくど
humus (soil)
ふしょくえいようこ
dystrophic lake
ふはい
corruption
くさる
to lose a bet
saprophagy
ふしん
taking great pains (to do)
ふようど
humus
くさり
rottenness
ふらん
decomposition
ふしゅう
smell of something rotten
ふせいどうぶつ
saprozoa