What is a high tunnel?

A high tunnel is indeed a type of greenhouse. High tunnels are unheated structures that are typically made of a plastic covering stretched over a frame. They are designed to extend the growing season for crops by providing a sheltered environment. This allows for earlier planting in spring and later harvesting in fall, helping farmers to protect their crops from adverse weather conditions, such as frost, rainfall, and wind.

High tunnels can create a microclimate that promotes plant growth by trapping solar energy, which warms the air and soil inside the structure. This results in enhanced growth conditions compared to traditional outdoor farming. They are particularly beneficial for specialty crops, as they allow for greater control over the growing environment, which can lead to improved crop quality and yield.

In contrast, other options describe different concepts in agriculture. Crop rotation is a practice used to maintain soil health and reduce pest pressure, soil amendments improve soil conditions and fertility, and pest control systems are strategies used to manage agricultural pests. None of these concepts pertain directly to the structure and function of a high tunnel.