The high nutrient enriched soil, long growing period and sufficient sunlight exposure are major factors which makes the marshes more productive than the bogs.
Explanation:
Marshes are one of the highly productive ecosystems just like the swamps. This is because of the following reasons –
a) High nutrient depositions due to the flow of nutrient enriched sediments of river though the marsh area
b) They have long growing period
c) Sufficient amount of sunlight exposure.
While bogs remain water choked most of time in a year and thus decaying plants and leaves form an important part of its soil. Such soils have low oxygen and nutrient content.