Seasonal High Tunnel Systems for CropsInterim Standard 798

Technical and Program Guidance

National bulletin: 190-10-10 National Bulletin: 190-10-12Idaho Bulletin: 300-12-7

NRCS IdahoDecember , 2011

Seasonal High Tunnel • Definition:

A seasonal polyethylene covered structure that is used to cover crops and extend the season in an environmentally friendly manner

• Practice lifespan: 4 years

• Available to all eligible agricultural producers (do you want to reference manual?)

- Improve plant quality- Improve soil quality- Improve water quality from reduced nutrient

and pesticide transport- Improve air quality through reduced transportation

input- Reduced energy use through local consumption

Purposes

• Plants not adapted or suited: Plants are not adapted and /or suited to site conditions or client objectives.

• Selected plants are adapted to the soil and climatic conditions or the site is modified to make it suitable for the desired plants.

• Plant Condition- Productivity, Health and Vigor: Plants do not produce the yields, quality, and soil cover to meet

clients objectives.

Potential resource concerns (SWAPA) that may be identified at the field site

• Soil Condition, Organic Matter Depletion: Soil Condition Index is positive.

• Soil Erosion, Sheet & Rill: Sheet and rill erosion does not exceed the Soil Loss Tolerance “T”.

• Soil Erosion, Wind: Wind erosion does not exceed the Soil Loss Tolerance “T” or, for plant damage, does not exceed crop damage tolerances.

•These resource concerns may only effect a small area 0.05 acre

Potential resource concerns (SWAPA) that may be identified at the field site

• Water Quality- Harmful levels of pesticides in surface water• WIN-PST tool

• Water Quality- Excessive Nutrients and organics in surface water• INTRA tool

Potential resource concerns (SWAPA) that may be identified at the field site

Condition Where Practice AppliesCropland where the growing season extension is

needed due to climate.Alfalfa /grain rotations are ok to install high tunnels

NPPH (… and forage crops in short-term rotations are cropland)

Not approved on pasture and rangelandAny commodity crop can be grown in the natural

soil profile. (i.e. specialty crops, garlic, raspberries)Raised beds allowed, but does not apply to crops

not grown in the natural soil profile (i.e. tables/benches, pots)

• Tunnel shall be constructed of metal, wood, or durable plastic and be at least 6 ft in height

Criteria

• The seasonal tunnel structure must be planned, designed, and constructed in accordance with manufacturer’s recommendation

• Shape• Ground Posts and Bows• Purlins and Truss Supports• Side walls and End walls• Ventilation and Access • Covering (Polyethylene Plastic)

Elements of a High Tunnel

• Quonset (Round Hoop)Typically 14 to 34 ft wide, 28 to 150 ft long

• Gothic (Peak)Require additional bracing 12 to 16 ft at peak

High Tunnel Shapes

Photos: Farmtex.com

Photo: Danny McBride NRCS, Utah

• “In climate conditions where snow loads may damage the structure, the tunnel cover shall be removed at the end of the growing season”

• As a minimum, a 6-mil greenhouse-grade, UV resistant polyethylene cover will be used

Criteria

• Steel pipe sunk about 3 ft deep with about 1 foot above ground

• Caution when producers use cement it may change their tax classification from temporary to permanent

Ground Posts

• Tunnel can be larger, but only pay up to 2,178 sq ft2012 National general payment rate - $ 2.55/ sq ft

• Producer can install multiple tunnels• Can already have an existing high tunnel that was not contracted with EQIP.

Payment Rate

Installation ConsiderationsOrientation

• N-S for main season, maximize airflow crosswise• Distance from structures/shade

–2x height of nearest structure• Quality soil• Access to water for irrigation• Drainage

• Runoff shall be directed away from tunnel to avoid ponding

– Surface or underground outlets– Protected ground surface– Critical area planting

− Grassed waterways• If runoff empties onto ground surface, a detention basin, storage reservoir, or stable outlet shall be provided

Criteria

• Surface or ground outlets such as rock pads, rock filled trenches with subsurface drains, concrete and other erosion-resistant pads, or preformed channels may be used

• Seeding and vegetation shall be established on all disturbed earth surfaces

Criteria

• Plan appropriate measures to address:– Conservation crop rotation– Irrigation water management– Nutrient management– Pest management– Runoff from the structure

• Access for pollinators or no cucumbers• Roll up the sides

Considerations

For general information and suppliers of high tunnel systems see web sites:

• hightunnels.org

•References in the standard with web sites

•University of Idaho http://www.extension.uidaho.edu/homegard.asp •Utah State University https://extension.usu.edu/yardandgarden/htm/vegetables-fruits-herbs