Bottle reforestation to combat desertification: a significant success (Willem Van Cotthem)

See former posting on January 30, 2010

BOTTLE REFORESTATION – a new method to combat desertification

From cutting to young tree

All over the world tree nurseries use plastic bags (mostly black ones) to grow tree seedlings.  Generally speaking, these seedlings are taken to the plantation site in their plastic bags, where these bags are cut open and the root ball is positioned in the planting pit. During that rough handling, the root ball is usually broken and the roots damaged, causing a lot 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 not take 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 the environment (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 the global level, we have been looking for a more efficient and cheap alternative.

Experiments with plastic bottles showed that this can be an interesting solution 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 after transplantation.

(c)   Enhance biomass production in a shorter period (stronger seedlings).

(d)  Enhance survival rate of the tree seedlings.

(e)   Enable reforestation at the most hostile locations.

(f)    Avoid pollution of the earth’s surface with plastic nursery bags.

Tree seedlings grown in bottles can very easily be transported to the plantation site without significant damage to the plants and their root system.  This makes this method very interesting for large-scale afforestation or reforestation programmes.  Therefore the method is called “bottle reforestation” or “bottle afforestation”.

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

Growing seedlings in plastic bottles – Variant 1

The simplest method is illustrated in a few steps with cuttings of the Navajo Willow (Salix matsudana ‘Navajo):

2010 – Fruit juice bottle 15 cm (6 inchs) high (Photo WVC)

2010 – Two perforations 2,5 cm (1 inch) above the bottom let a possible surplus of irrigation water run out of the bottle (to avoid acidification of the potting soil inside and to avoid asphyxiation of the roots) – (Photo WVC)

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

2010 – Rooted willow cutting planted in plastic bottle filled with potting soil. Only a minimal quantity of water is needed to keep the potting soil moistened for a very long period (almost no evaporation) – (Photo WVC)

2010 – Soon after planting the cutting in the bottle new shoots are formed and roots are growing towards the bottom of the bottle (Photo WVC)

2010 – In less than 1 month a young willow is developed, ready to be planted (Photo WVC)

USING YOGURT POTS AND DIFFERENT TYPES OF BOTTLES

2010-02 – Avocado seed germinating in a mini-greenhouse made of to yogurt pots (Photo WVC)

2007-06 – Tree seedlings of different species are successfully grown in different types of plastic bottles and pots (Photo WVC)

STARTING WITH CUTTINGS OR SEEDS OF TREE SPECIES

2010-05 – Rooted spekboom cutting (Portulacaria afra) in a Coke bottle, perforated 2,5 cm (1 inch) from the bottom (for drainage) – (Photo WVC)

2010-08 – Avocdo seedling with well-developed root ball in a Coke bottle. The bottom part has been cut off to set the root ball partly free, the upper part remaining in the bottle to continue water absorption, thus avoiding drought shock and transplant shock (Photo WVC)

2010-08 – The major part of the plastic bottle is kept intact to protect the root ball. The lower part of the root ball is set free, ready to be in direct contact with the soil in the plant pit (Photo WVC)

2010-08 – Avocado seedling grown in a taller plastic bottle of which the bottom part was cut off and the bottle itself taken away to show the excellent root development (Photo WVC)

2010-08 – Planted avocado seedling with the upper part of the bottle sitting above the surface in the plant pit to enable efficient watering of the root ball, which is kept humid for a longer time inside the major part of the bottle. The lower part of the root ball is in direct contact with the soil in the plant pit. It receives a lot of percolating water poored in the bottle top (Photo WVC).

2010-08 – The results of this “bottle reforestation method” are significantly better than the one with the classical black plastic bags. For the advantages see the introductory text (Photo WVC)

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About Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.
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