Editing Polytunnel (section)

==Development==
[[File:Hoop house.jpg|thumbnail|A Missouri farmer inspecting an early tomato crop in a hoop house.]]Hoophouses have existed at least since the 1940s, but they are much more commonly used with each passing decade, and their design continues to evolve. Because of the wide variety of constantly changing designs, in reality there is an entirely [[continuous function|continuous]] spectrum from high tunnels through low tunnels to the simplest row covers, although they are often thought about as discrete steps. Major themes of continuing development are (1) achieving the same results with lighter construction and less cost and (2) making hoophouses easily movable. The advantages of mobile hoophouses include greater [[return on investment]] (with the same unit of investment getting greater use per year across different crops in different months) and more flexibility on [[crop rotation]] without ever having to bother to dig the soil out of a stationary house (or use [[soil steam sterilization]]) to cure greenhouse soil sickness.

A [[US Department of Agriculture]] program is helping farmers install polytunnels. The program was announced at the US [[White House]] garden in December 2009.<ref>{{cite press release |title= USDA to launch high tunnel pilot study to increase availability of locally grown foods |author= Office of Communications: [[United States Department of Agriculture]] (USDA) |url= http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?contentidonly=true&contentid=2009/12/0617.xml |issue= Release #0617.09 |date= 16 December 2009 |location= Washington, DC |archive-url= https://web.archive.org/web/20100131040940/http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?contentidonly=true |archive-date= 31 January 2010 |url-status= dead }}</ref>

Farmers in [[Iraq]] are building these in increasing number and adding [[drip irrigation]] to grow tomatoes.<ref>{{cite web |last= Tharp |first= Mike |date= 17 July 2009 |title= Once world's bread basket, Iraq now a farming basket case |work= McClatchyDC |publisher= [[The McClatchy Company]] |url= http://www.mcclatchydc.com/2009/07/17/72051/once-worlds-bread-basket-iraq.html }}</ref>