Hoop houses, also known as Low or High Tunnels, are a modified form of greenhouse. They are designed to offer cover to crops planted directly in soil. Use of hoop houses was incentivised for farmers throughout the United States by an experimental program offered through the U.S. Department of Agriculture. In 2014, the USDA transitioned a successful pilot project initiated several years previously. The Department's Natural Resources Conservation Service Environmental Quality Incentives Program became a standard practice when it was determined that farmers who used hoop houses could not only extend the growing season for their crops but also reduce their use of pesticides and nutrients, improve soil quality, meet growing demand for fresh, local produce, and boost their profitability. It became a win-win situation for the growers and contributed to better plant management and higher production. In the five-year period between 2010 and 2015, more than 14,000 hoop houses were built with USDA assistance, in all 50 states and U.S. territories, with a total cost-sharing expenditure of approximately $93 billion.
The technical assistance provided by the USDA to farmers under the program was a unique answer to an agricultural need for economical low-input agriculture that delivers great benefits not only to farmers but also to consumers. Hoop houses differ substantially from more robust greenhouses in the way that they are stabilized and anchored to the ground. They provide a form of simple shelter for crops, and they modify the growing environment in a beneficial way, extend growing seasons, and shield sensitive crops from high wind and excessive heat. They are actually considered "temporary" structures, and farmers gain some tax advantages with that designation. However, in practice, once a hoop house is installed, it only rarely is moved. Hoop houses are typically Quonset-style, but they can also be gabled or Gothic-style, and they often have roll-up sides to allow for substantial air circulation. Crops may be irrigated as needed, and drip irrigation is more effective when used under such covers. Crop rotation is beneficial, just as it is in open fields, allowing farmers to plant and harvest different crops in summer and winter, and to maintain soil health by selecting crops that replenish needed soil nutrients.
