GREEN-Seeds.com
General Cultivation Techniques

BY DR. FRANKLIN W. MARTIN
Published 1991

WHY A FENCE?

There are several reasons that a small farm needs fences:

The fence represents an investment of labor and/or money. Both items are always scarce on the small farm. While in general labor and money are interchangeable, it is always desirable to limit both. While a fence costs something, it also yields something -- protection. On a small farm it is always desirable to increase the yield, that is, the positive results obtained through money and effort.

A living fence can increase the yield of labor. Major fences are usually constructed of poles and wire. Minor fences, such as those used for fencing small animals, can be constructed entirely of wood, or of poles, slats, and woven wires. Major and minor fences can be constructed principally of living poles, thus reducing the costs of the initial price of the fence. Usually living poles will last much longer than wooden (dead) poles and thus maintenance may be reduced.

Living fences are widely used now in a wide range of ecological situations, from very dry to rain forest conditions. Suitable plant materials are available for almost all ecological conditions.

Other Benefits from a Living Fence

Firewood

As a general rule, firewood is used for cooking in third world countries. A living fence post can be trimmed periodically and the branches can be used as firewood. Where wood is scarce, this means that firewood is produced readily near the farm home where it will be used. Extra firewood may be sold or bartered.

Fertilizer

The leaves that fall from the tree as well as the leaves and small branches cut away on harvest of trees for firewood can be (1) composted, (2) immediately mixed with the soil as fertilizer, or (3) left on the ground as a sheet mulch. Because trees are deep rooted they bring mineral nutrients from the deep soil that may not be available to annual crops. After residues from trees rot in or on the soil, such minerals are released into the soil and become available to crop plants. If the tree is leguminous the amount of nitrogen in the leaves will be large enough to significantly affect crop yields. Furthermore, pruning of trees results in partial die back of roots, releasing additional nutrients directly into the soil. Nitrogen is always difficult and costly to obtain, and leguminous trees are a principal way to get nitrogen from trees.

Other Uses

Feed. The leaves of many trees are edible as feed for small animals. The edibility of leaves as feed varies not only from species to species but also with age. When fence posts are used to produce feed, space is conserved on the farm.

Food. Leaves, flowers, fruits and seeds of some species might be good food for people. Knowledge of these edible qualities might be useful in producing food for family use and for sale.

Fibers. A few plants in living fences yield from large or small branches that can be used directly for tying, can be retted (rotted under water), or can be pounded into useful fiber or cloth.

Shade. Trees may provide welcome relief from the hot sun for people or animals.

Construction materials. Many trees can be harvested for their wood, which then can be used for construction of building, small articles, or artwork, or be sold.

Medicines. Some plants used in fences are also used in primitive medicines. However, caution is recommended in their use.

Windbreaks. In some areas windbreaks might be very necessary to protect against winds and thus to permit the growth of some crops.

DISADVANTAGES OF LIVING FENCES

Some living fences can have serious disadvantages as follows: 

Because of these reasons, living fences have to be controlled. Whether or not living fences are used on the farm will depend on the weighing of the advantages versus the disadvantages.

ESTABLISHMENT AND CARE OF LIVING FENCES

The tradition of living fences varies from place to place in the tropics, as does the suitability of the various species used to make them. There may be many other species of trees that are well suited that have not come to the attention of the author. In any area it would be desirable to investigate the trees that are already being used as living fences. It might also be appropriate to select for suitable species for living fences in the wild.

If new species are selected, they should have the following characteristics:

If suitable materials are not locally available, then importation of seed might be desirable. The species most recommended would be: 

Trees and other plants are used as living fences in three principal ways: posts, hedges, and palisades (a fence of closely set stakes). While any tree can be used as a living post, many trees would not normally be so used because of their size, propagation difficulty, slow growth, adverse characteristics, or inadequate lifetime. A few large trees used as occasional posts are retained for other values (teak as valuable wood, mango for fruits and shade). The majority of the species used as living fence posts can be propagated from large woody cuttings, generally the size of the fence pole required. There are, however, exceptionally fast growing trees that are planted from seeds. 

Posts are used with conventional barbed wire or wire screen. Plants that are used in hedges tend to be spreading so that they fill in the spaces between them rapidly. They may or may not be strung with wire. Plants used as palisades are planted very carefully as close together as necessary in order to achieve an animal proof cage-like fence immediately. Such plants may be propagated from stakes or offshoots.

Living fences are seldom fertilized. They are often pruned, however, to form them, to obtain new planting material or other products, and to eliminate excess foliage. In some cases, pruning is an annual task, usually done during the dry season. Fences can be carefully formed by weaving and tying branches, if so desired. Insects and disease are seldom a problem.

SPECIES FOR LIVING FENCES

Exceptional Species

Only a few species very widely used are featured here (see Table 1 for a listing of additional species.) 

Gliricidia sepium, Mother-of-cacao (madre-de-cacao, madera negra, mata raton). This small leguminous tree is so well known to farmers in some countries and so useful that it has been given a medal in Honduras. Common from low to medium elevations, the tree prefers a medium rainfall, and is well adjusted to a periodic dry season. The tree can be propagated from branches. An old living fence post will tend to produce a large number of long, narrow branches, perfect for planting. The branches root readily but the rate of growth is moderate. Gliricidia can also be propagated from seed. 

A narrow fence with broad crown is produced. Its lifetime is almost indefinite. The wood of old trunks become black and very hard, and so are useful for many small objects. Animals tend to feed on the foliage, but in fences most is borne out of their reach. The foliage is a useful feed in moderate amounts but there is some question of its toxicity in large amounts. Flowers, buds, and very young leaves are often cooked as a vegetable. The dry seeds are poisonous and are ground and mixed with other grains as a rat poison. Leaf fall occurs during the dry season and the leaves make valuable mulch. The tree was used in the past as a shade tree for cacao and coffee, but now has been replaced by Inga species. On triennial pruning a good quantity of firewood is produced. Pruning also results in root dieback and release of nitrogen to the soil.

Erythrina berteroana, Dwarf immortelle (bucar o bucare enano). This leguminous tree is small to medium in size, and is commonly used as a living fence post or a support tree for vine crops. Other Erythrina species may be substituted it. The tree is covered with dense foliage that is perennial. Because the leaves are not lost during the dry season, this tree is best suited for regions with somewhat more rainfall than is required by Gliricidia. Propagation is from branches, big or little, usually planted where they will be used. However, seeds can also be used. Growth is moderate to rapid. The fence is narrow with a dense crown. The foliage is attractive to animals and frequently used for feeding rabbits, sometimes with ill effects.

The wood is soft and of limited use except for fuel. On pruning the tree a large amount of useful mulch is produced. The seeds are poisonous. This is a favorite shade tree for coffee in Central America.

Yucca elephantipes , Yucca azote. This is one of the most common plants in living fences in Central America. Cuttings of branches large and small are frequently planted close together, and as they grow, make a practically impenetrable wall. The tree is easy to propagate, slow to grow and has a long life. The flowers are edible. 

Bursera simaruba, Gumbo limbo (indio desnudo, jinote). Gumbo limbo is especially appropriate for dryer areas where madre-de-cacao is not suited. Planted as large posts, it will root even under fairly dry conditions. This tree has few other uses, for even its wood is soft and short lived.

Moringa oleifera, Horseradish tree. This "vegetable tree" is one of the most successful plants in ECHOís seedbank. It handles dry seasons well and grows especially quickly the first year. The Asian Vegetable Research and Development Center in Taiwan has developed a gardening plan which starts with palisade of moringa grown from closely spaced seed. Trees are pruned at about head height, and the leaves used as a nutritious cooked vegetable or for animal feed. 

Additional Species Used as Living Species

See Table 1 for a listing of several species of plants that can be used in living fences. Most of these seeds are not available through ECHOís seedbank. Those that we do have are only available in small trial packets ­ not enough for a living fence.

If you want us to refer you to a commercial source of seed, please be sure to mention this in any correspondence.

* Altitude: 1 ­ 0 to 2000 meters; 2 ­ 2000 to 4000 m; 3 ­ 4000+ m

Moisture: 1 ­ low (30-50 inches/yr); 2 ­ medium (50-70 inches/yr); 3 ­ high (70+ inches/yr)
 

* Altitude: 1 ­ 0 to 2000 meters; 2 ­ 2000 to 4000 m; 3 ­ 4000+ m

Moisture: 1 ­ low (30-50 inches/yr); 2 ­ medium (50-70 inches/yr); 3 ­ high (70+ inches/yr)