Natural Resources Conservation Service s56

Natural Resources Conservation Service Caribbean Area

(Code 382) Specifications Guide

DEFINITION: A constructed barrier to animals or people.

Intended use of fence

Fences are designed and constructed to facilitate management of land uses. These are constructed considering people, vehicles or type of animals or to restrict movement to areas such as: pastures, crops, and/or riparian areas. Construction materials’ play an important role in decision making as some materials last longer than others. Fences can also be constructed using trees as a component that will provide other benefits such as connectivity, diversity, shelter and fodder for livestock and wildlife species. NRCS Caribbean Area October 2012 Permanent Fence Types

A permanent fence is designed to be in place for a period of many years, and its maintenance is minimal compared to temporary fences. In humid and coastal climates such as in the Caribbean Area, construction materials usually have a life span that is reduced by environmental factors such as: frequent high air and/or soil humidity, high solar radiation, and ocean water drift in the coasts. These factors promote rust in wire and steel posts, and rotten wood posts especially if these are non-treated low quality wood. Untreated softwood posts rot quickly and have a life span of 1 to 3 years.

With the post sitting permanently in water the wood rots very quickly leading to premature weakness. Having a layer of gravel in the bottom of the hole can help with drainage. A problem often arises when a fence post is set completely into concrete. Posts can prematurely rot when completely encased in concrete. Adding gravel to bottom of hole may add life span of the wooden post. Depending on site conditions you may consider corner and gate posts concreted.

A galvanized wire size 12 ½ Class 1 in a dry climatic condition may last 11 years without rusting, while in humid or coastal conditions the same wire may last 6 and 2 years respectively until rust appears. The Standard Steel Gauge is a terminology used to describe a standard wire size by its diameter. Note that as wire size increases, smaller gauge numbers are used. Wire materials are marketed in four weights; light, medium, heavy and extra heavy. Light weight wires have a short life, while heavyweight wires have a longlife so they last longer. Table 1. shows the relation between wire gauge and diameter commonly used in the Caribbean Area.

Table 1. Relation between wire gauge and diameter. Wire gauge Diameter mm (inches) 12.5 2.50 0.0985 15.5 1.72 0.0677

Most common permanent fences are built with high quality wood or steel posts and barbed or woven wire. Other alternatives for constructing fences include living stakes alternated with wood or steel posts and a combination of these construction elements. For dry areas prone to wildfires, steel posts may be the first alternative although wood posts may have a longer life span than those located in humid areas, so a combination of steel and wood posts may be considered in the same design.

Treated wood posts shall be used. Select wood with a moderate bending strength, low decay (wood posts will rot off at ground), weather resistance, high nail-holding power and freedom from twist. As a general rule, the steep and uneven the terrain, the more close the line posts must be installed. As a general scenario in the Caribbean Area, most topography (75% or more) is

NRCS Caribbean Area October 2012 considered steep land. This rationale is used to establish line posts 8 feet apart. Support posts (madrinas) must be established every 40 feet in-line to provide extra support.

Fence design and construction should consider ease of access for construction, repair and maintenance.

Barbed Wire Fence

These are made with 2 or more strands of smooth galvanized steel wire which are twisted together with 2 or 4 sharp barbs spaced every 4 to 6 inches. The standard barbed wire fences usually have about 11 line posts per 80 feet. Posts must be arranged as follows: One corner post followed by four regular 2.5-3.00 inches diam. (or steel) posts at 8 feet apart maximum- followed by one 6-8 inches diam., line post or “madrina” (every 40 feet maximum) to provide extra support. Regular line posts usually come with an entire diameter of 3 inches, but it is common to find a single post with 2.5 inches diam top and 3.00 inches bottom. Regular line posts shall be either 3 inches diam or a single post of 2.5 to 3. inches. Regular line posts with 2.5 diam only are not allowed in this guide. All wood posts shall be treated. Depending on the location (division or subdivision), the fence may have 3 to 4 (or more) strands of wire. Living stakes can be installed between line posts in some instances but they shall be placed parallel to an already installed permanent fence. Depending on the purpose and tree species, living stakes are to be installed 8 to 40 feet apart depending on tree species size and objectives of the landuser. Living stakes or trees will not substitute line posts (either 2.3-3 inches diameter or 6-8 inches diameter “madrinas”). Trees are recommended to create ecological corridors, provide food and shelter for wildlife and biodiversity. Trees shall not be tied to barbed or woven wire.

Woven Wire Fence

These fences consist of a number of horizontal lines of smooth wire held apart by vertical smooth wires called stays. The spacing between the horizontal lines vary from 1 ½ inches at the bottom to 9 inches at the top. Spacing of horizontal lines generally gets wider as the fence gets higher. Stay wires are usually spaced 6 inches apart. The height of most woven wire for fencing used in the Caribbean Area is 48 inches. As for the barbed wire fence, line posts for woven wire fences, must be arranged as follows: One corner post followed by four 2.5-3.00 inches diam., (or steel) regular line posts 8 feet apart maximum- followed by one 6-8 inches diam., line post or “madrina” (every 40 feet apart maximum) to provide more support. (Regular line posts usually come with an entire diameter of 3 inches, but it is common to find a single post with 2.5 inches diam top and 3.00 inches bottom. Regular line posts shall be either 3 inches diam or a single post of 2.5 to 3 inches. Regular line posts with 2.5 diam only are not allowed in this guide. All wood posts shall be treated. In many occasions a single or double line of barbed wire is placed at the top of the woven fence to provide more restriction to movement. Generally, corner and “madrinas” posts are wooden. Living stakes can be installed between line posts in some instances but they shall be placed parallel to an already installed permanent fence. Depending on the purpose and tree species, living stakes are to be installed 8 to 40 feet apart depending on tree species size and objectives of the landuser. Living stakes or trees will not substitute line posts (either 2.3-3

NRCS Caribbean Area October 2012 inches diameter or 6-8 inches diameter “madrinas”). Trees are recommended to create ecological corridors, provide food and shelter for wildlife and biodiversity. Trees shall not be tied to barbed or woven wire.

Passageways for Persons or Water Only

Passageways are structures that can form part of a fence but are usually constructed to facilitate farm activities or across streams that will permit water and debris to pass (as floodgates), but still fence livestock. Passageways are designed for specific conditions and vary in dimensions and materials. For standard designs see the Caribbean Area Fence Drawings.

Gates may be constructed using different materials. Use the same materials used for wood/wire fences or, aluminum, metal pipe or timber. Gates must be easy to handle, provide space for its intended use and animal type and be durable. Generally gates are built to permit a tractor or farm machinery to pass through especially if the pasture is harvested for green chopped or hay, or if it is mowed as a management practice to eliminate woody species and old growth. When locating gates, consider the corners of the fields as first option as livestock tends to move to those areas making it easier to manage them. Corners generally have funnel shape.

NRCS Caribbean Area October 2012 Criteria for Selection

For criteria to select materials and construction dimensions in the Caribbean Area. See Tables 2 to 5. Table 2. Fence Selection Criteria for the Caribbean Area.

Purpose of Fence Post Material

Animal Type Fence Type to Control Boundary Interior Riparian Areas Subdivision High Quality Treated Standard Steel Corner and Wood (regular line (Shape: U,T,Y,) “Madrina” Treated posts)/1 Posts (all)/2 Minimum Minimum Minimum Minimum Minimum Minimum Meets Minimum Criteria? diameter Length diameter Length Diameter Length (in.) (ft.) (in.) (in.) (in.) (ft.) Cattle/Horses Barbed 3 wire 15.5 No No No Cattle/Horses Barbed 3 wire 12.5 No Yes No 2.5 to 3 or 6.5 N/A 6 6 to 8 or 8 3 8 Cattle/Horses Barbed 4 wire 15.5 No Yes No 2.5 to3 or 6.5 N/A 6 6 to 8 or 3 8 Cattle/Horses Barbed 4 wire12.5 Yes Exceeds Yes 2.5 to 3 6.5 N/A 6 6 to 8 or 8 or3 8 Cattle/Horses Barbed 5 wire 15.5 Yes Exceeds Yes 2.5 to 3 or 6.5 N/A 6 6 to 8 or 8 3 8 Cattle/Horses Barbed 5 wire 12.5 Exceeds Exceeds Exceeds 2.5 to 3 or 6.5 N/A 6 6 to 8 or 8 3 8 Cattle/Horses Barbed 6 wire or Exceeds Exceeds Exceeds 2.5 to 3 or 6.5 N/A 6 6 to 8 or 8 more 3 8 Goat/ 4 ft. Woven wire + Yes Yes Yes 2.5 to 3 or 6.5 N/A 6 6 to 8 or 8 Sheep/Horses 1 strand of barbed 3 8 /Wild dogs wire above. Deer 8 ft. Woven wire + Yes Yes Yes 2.5-3 12 N/A 12 6 to 8 or 12 1 strand of barbed 8 wire above. /1 Regular wood line posts 2.5 -3 or 3 inches diameter and 6.5 feet long minimum, treated wood only. /2 Corner consist of wood posts 6-8 inches diameter minimum and 8 feet long minimum. “Madrinas” are line posts 6- 8 inches diam/6.5 feet long. minimum.

NRCS Caribbean Area October 2012 Table 3. Barbed Wire, Setting and Accessories Specifications.

Wire (galvanized/new Wire Size Description Space between wires only) 3 strands 4 ≥5 strands strands Bottom wire set at 10 All All 10 10 10 inches above ground maximum Barbed Standard Double 12.5 or 15.5 Galvanized 10 to14 10 to 14 10 to 14 Strand gauge with inches inches inches barbed apart apart apart spaced 4 to 6 inches apart. Standard Woven Wire 48 10 or 12 ½ Galvanized N/A N/A N/A inches gauge Staples or fasteners 9 gauge galvanized. 1 ½ inches. To fasten living stakes (live trees) use smooth wire, wire clip or staples. Never tie wire around the trunk; this may reduce tree capability to tolerate strong winds.

Table 4. Post Setting Specification.

Post Type Placing Depth Rocky Soils All Other Notes Regular line Post. 18 22 8 feet apart. Treated. Standard Steel (U,Y,T) Anchor plate must be fully below ground surface (Post is approximately 15 to 18 inches deep) Corner & Support 36 36 “Madrinas” 40 feet apart (“madrinas”) Treated. Living stakes or Trees For local tree species see Table 5. Refer to Conservation practice: Silvopasture (Code 381 )

NRCS Caribbean Area October 2012 Table 5. Fence Specifications. Local Tree Species for Living Fences/1. Habitat Spanish English Technical Name Spacing Semiarid Humid Common Common (ft.) lowland lowland Name Name and and upland upland Abeyuelo Greenheart Colubrina arborescens 8 x Achiotillo -- Alchornea latifolia 8 x Almácigo Turpentine Bursera simaruba 8 x x Bariaco Black Krugiodendron ferreum 8 x ironwood Bucare, Mountain Erythrina poepigiana 16 to 40 x Bucayo immortale gigante Burro prieto Black wattle Capparis cynophallophora 8 x Caoba Honduras Swietenia macrophylla 16 to 40 x x hondureña mahogany Caña fistula Golden Cassia fistula 16 x x shower Canelón -- Ocotea cuneata 16 x Capá colorado Red manjack Cordia nitida (laevigata) 8 to 16 x Ciruela del Jamaica plum Spondias purpurea 16 x país Cojoba -- Pithecellobium arboretum 16 x Emajagua -- Hibiscus pernambucensis 16 x Emajaguilla Cork tree Thespesia populnea 16 x x Espino rubial Prickly ash Zanthophyllum martinicense 8 to 16 x Guaba -- Inga vera 16 x Guacima Bastard cedar Guazuma ulmifolia 16 x Guamá Madras thorn Pitchecellobium dulce 16 x x americano Guara -- Cupania americana 8 x x Guaraguao Musk wood Guarea trichiloides 16 x Higüerillo -- Vitex divaricata 16 x Hugüero Calabash Crescentia spp. 8 x x Jaguey blanco Boislaglu Ficus laevigata(citrifolia) 16 x Jobo Hogplum Spondias mombin 16 x Laurel geo -- Ocotea leucoxylon 16 x x Mabí Naked wood Colubrina reclinata Machete -- Erythrina berteroana 16 x (Bucayo enano) Mata ratón, Mother of Gliricidia sepium 8 to 16 x x San José cacao Moca Cabbage bark Andira inermis 16 to 40 x Pendula, Citharexylum fruticosum 8 x x Balsamo Old woman,s bitter Retama, -- Lonchocarpus latifolius 8 x NRCS Caribbean Area October 2012 Hediondo Roble blanco White oak Tabebuia heterophylla 8 to 16 x x Roble Pink trumpet- Tabebuia rosea 16 x venezolano tree Tachuelo Fustic Pictetia aculeata 8 x Tinacio, Cabo Broomstick Trichilia hirta 8 x x de hacha Úcar Black olive Bucida buceras 16 to 40 x x /1 This list is not all inclusive. For other potential species consult the Grasslands Specialist. Planting distance can vary from this table depending on site conditions and purpose.

Operation and Maintenance: landusers must inspect fences and their intended use regularly and must keep their integrity at least during their lifespan. Inspection after storms and other disturbance is necessary to insure their continued use. Precautions should be taken to ensure the safety of construction and maintenance crews.

NRCS Caribbean Area October 2012