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BOTTLE REFORESTATIONA new method to combat desertification

Willem VAN COTTHEM

University of Ghent (Belgium)All over the world tree nurseries use plastic bags (mostly black ones) togrow tree seedlings. Generally speaking, these seedlings are taken to theplantation site in their plastic bags, where the bags are cut open and theroot ball is positioned in the planting pit. During that generally roughhandling, the root ball is usually broken and the roots damaged, causing alot of difficulties to get the seedlings growing due to transplant shock.

It is well known that many people, after tree planting in the field, do nottake care of those useless pieces of plastic bags, which are then left(littered) at the planting site. That is one of the reasons why one can find

plastic nursery bags almost everywhere at plantation sites, polluting theenvironment (trees are blooming with colored bags).

Considering the heavy pollution load of plastic bags on the environment,and considering that billions of plastic bags are used every year at theglobal level, we have been looking for a more efficient and cheapalternative.

Experiments with plastic bottles showed that this can be an interestingsolution to:

(a)Reduce the damage to the root system at planting time.(b)Reduce the volume of irrigation water needed to keep the seedlings

alive (higher water use efficiency WUE) before and aftertransplantation.

(c) Enhance biomass production in a shorter period (strongerseedlings).

(d) Enhance survival rate of the tree seedlings.(e) Enable reforestation at the most hostile locations.(f) Avoid pollution of the earths surface with plastic nursery bags.

Tree seedlings grown in bottles can very easily be transported to theplantation site without significant damage to the plants and their root

system. This makes this method very interesting for large-scaleafforestation or reforestation programmes. Therefore the method is calledbottle reforestation or bottle afforestation.

Different variants of growing tree seedlings in bottles can be used. Thefirst will be described below, others will follow.

Growing seedlings in plastic bottles Variant 1

The simplest method is illustrated in a few steps:

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2010 - Fruit juice bottle 15 cm (6 inches) high

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2010 - Two perforations 2,5 cm (1 inch) above the bottom let apossible surplus of irrigation water run out of the bottle (to avoidacidification of the potting soil inside and to avoid asphyxiation ofthe roots)

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2010 - Willow tree (Salix matsudana) cuttings, rooting in water for 1-2 weeks

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2010 - Rooted willow cutting planted in plastic bottle filled with potting soil. Only a minimalquantity of water is needed to keep the potting soil moistened for a very long period (almost

no evaporation).

http://desertification.files.wordpress.com/2010/01/first-leaves-p1020927-b.jpg

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2010 - In less than 1 month a young willow is developed, ready to be planted.

http://desertification.files.wordpress.com/2010/01/young-plant-p1030029.jpg

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One can also plant 2-3 willow cuttings in a bottle filled with potting soil(left). A lot of irrigation water is saved, because evaporation is low(percolating water stocked at the bottom 2,5 cm and evaporation occursonly at the surface of the potting soil in the bottle, thus less influence ofthe wind).

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Once the young trees have developed a good root system, with a bunch ofroots sitting at the bottom, the bottles can be transported to theplantation site. One can expect less damage to the roots than with theclassical plastic bags, because the root ball sits well fixed inside the bottle.

Planting the young trees

At the plantation site, plant pits with a diameter of 2-3 times the diameterof the bottles are prepared. Each bottle is placed close to a plant pit.

With a pair of scissors the lower part of the bottle (e.g. 2,5 cm or 1 inch) iscut off, leaving the bottom part of the root ball hanging out of the bottle(again less damage to the root ball than with plastic bags).

After pouring some water in the plant pit, the bottle with its young tree isplaced at the bottom of the plant pit so that the lower part of the root balltouches the humid soil and the top of the bottle is level with the surface of

the plantation site.

The plant pit is filled with the surrounding soil and some additional wateris poured in the bottle. That water will run through the bottle, where ismakes the root ball completely moistened and the surplus will run into thelocal soil, moistening the bottom part of the root ball hanging outside thebottle.

Thus, the young tree will not get a serious transplant shock and it willswiftly continue its growth in the local soil, keeping survival rate very high,even if post-plantation irrigation is difficult or impossible.