Tree Production in Gutters Print
Of interest to growers

 

A gutter system for tree growing?  Now that’s unique!  The system described below deviates considerably from what one would normally expect of container production for trees, even though gutters have been a mainstay for many years in the production of crops such as strawberries, lettuce, cut mums and anthuriums.

There are a number of reasons to develop a gutter system specifically for the production of trees. In the marketplace, the quality and sustainability requirements of tree production are forever increasing.  Further, European guidelines for the use of fertilizers and crop protection products also require a critical look at production systems.  In a number of field production systems the guidelines for water quality and nitrate run-off have not yet been met.  As well, labor costs and working conditions in many field production crops still need to be improved.  While much of the heavy work is done by machine, the low-to-the-ground work, such as grafting and tying is still tough on the body and can cause long-term problems.


The last, but certainly not the least important reason for development of the gutter system is soil conditions during fall harvesting.  The heavier the soil, the worse the damage caused by machinery during wet weather.   If necessary trees can be dug by hand, but they still need to be moved to storage and, one way or the other, a tractor and wagon needs to go into the wet field.

The starting point was an experimental system tested in 2005, which was used to grow conifers in buried gutters.  For harvesting, the plants were simply pulled out of the gutter single file and separated.  An above ground version was also tested.

Gutters, which are laid out and tied to posts, are filled with growing medium in February and are planted up with winter grafts.  Subsequently the plants are tied to a stake and in September/October they are removed from the gutters and transplanted to the field or larger containers.

The prototype for such a system was technically quite simple.  However, no practical application had ever been tested, nor had any research been conducted. Subsequently a horticultural research agency became involved with the system and helped growers to develop it further.

A number of the production gutters have been equipped with catchment gutters that capture excess water and nutrients to allow for recycling as well as measurement.  This is part of the development of a closed system.  Several species of trees are being evaluated in gutters in relation to production in the field. Several different shapes and sizes of gutters are being tested.  Moisture sensors have also been installed.

Further innovation will be required to develop a system that is practical and economical. In the meantime other nursery production sectors, fruit tree producers and vegetable growers have all expressed an interest in the research.

The gutter production systems use a computer-controlled drip irrigation system.  Sensors, which are wirelessly connected to a central computer, measure moisture levels, temperature and fertility levels. One can then remotely evaluate the need for water and nutrients and turn on the drip irrigation and fertilization units.  Strictly scientific measurements will also be taken for leaf temperature and leaf thickness.  A solar irradiation sensor is also coupled to the computer.

The gutter system has been installed on an area of 3,500 sq. meters (.85 acres).  A total of 70 gutters each 50 meters (55 yards) long are used.  The gutters are attached, in pairs, to concrete posts that have been anchored 1 meter (39”) deep in the soil.  The gutters are hung at a height of 60 cm (36”) above the ground to reduce the amount of bending required for jobs such as tying.  One could even hang a cart from the gutter and move along as if working at a desk.  At the top of the posts wires are guyed, from which bamboo canes are hung by clips.  The intent is to remove the stakes after one season and leave them hanging from the wires over winter.  They will not require storage and can be reused immediately next spring.  

The gutters are made from high density perforated plastic, allowing the roots to be air-pruned all the way around.  The perforated material is bought in rolls, bent into the gutters by machine and filled with growing substrate.  The gutter is then inserted into the profile and pulled in place.  Then plants are added. Three different substrates (growing media) are under study, all with peat as their major component.  The optimum growing media will be deduced from these trials. Every gutter has a drip tube with an emitter every 20 cm (8”).

Two sections of the gutter system are equipped with catchment gutters.  The intent is to connect these gutters to a tank, the contents of which can be measured for water and nutrient absorption in the system and the watering and fertilization strategy adjusted accordingly.

Researchers are still looking for answers to many questions such as:
•    What is the optimum water delivery to optimize growth?
•    Is an overdrain necessary to prevent salt build-up?
•    Can liquid feeding produce better results than controlled release fertilizers?

While it likely that this innovative tree growing system is still several years away from full-scale commercial production, it nonetheless represents an exciting new development in tree production.

Source:
photos:  Arno Engels, De Boomkwekerij www.deboomkwekerij.nl

 
 

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