There are several strategies for improving air circulation under hay cover to prevent moisture buildup. One effective method is to elevate the hay slightly above the ground on pallets or other supports, which allows air to flow underneath, lowering humidity and reducing the risk of moisture absorption.
Leaving small gaps or vents around the edges of the cover can also improve airflow and prevent the accumulation of humidity. If animal incursion is a concern, those gaps can be backed by a durable mesh material.
