Design for: Het Groeilokaal

By Henk Eshuis

Online PDC 2015 given by Geoff Lawton

Project description

Through facebook I got in contact with Astrid Huijbregts (http://www.hetgroeilokaal.nl/) who is

starting a new initiative in the Netherlands, ‘Het Groeilokaal” . She was looking for people who

could help with a permaculture design and I was looking for a site to design. So I took the

opportunity to do the design exercise on Het Groeilokaal.

Het Groeilokaal is an initiative to get the local population and especially children more involved in

nature and food. My task was to design a food forest and teagarden. To the south there is a bicycle

path and the idea is that people can stop there and visit the garden and food forest. The actual

“Groeilokaal is a circle of closely planted Pinus silvestris trees on the field to the left. The idea is

that those trees will merge together over time forming a living school.

The terrain is in total 18 hectare and is a former mobilization terrain (MOB) of the Dutch army. At

the moment it is still property of the government. A few years ago all buildings have been

demolished. Since then nature is slowly taking back the terrain. Officially this area is a protected

nature area so only “indigenous” species can be used.

For my exercise I concentrated on a smaller part of the open area you can see in the red square

below of about 4000 square meter.

Het Groeilokaal is situated close to the city of Tilburg, in the image above you can see the MOB

terrain. The coordinates are: Latitude 51.59207 Longitude: 5.06462, The altitude is 13,7m above

sea level.

The site is about 80km from the sea. The land is more or less flat. From LiDAR data I got that the

terrain is between 13,6 and 13,8 m above sea level, almost perfectly flat. The only thing is that

there is a small ditch around the northern part of the terrain of about ,5 to 1m deep. There is no

open water available.

The forest around the spot consist mainly of 4 tree species, Birch (Betula pendula), Pine (Pinus

sylvestris), Summer oak (Quercus robur) and American oak (Quercus rubra). See the image below

for a general idea.

After the demolishing of the buildings there is a lot of regeneration taking place of pine and birch.

Also there are some small patches of heather (Calluna vulgaris). As can be seen in the pictures

below.

Climate: The climate in Tilburg is hardiness zone 9 (10a USDA) with average minimum temperatures not getting below zero. Average rainfall is around 800mm/year and is fairly distributed over the year, see the table below. Prevailing winds are from the southwest The data below is based on registered weather data and applies to Tilburg:

 

 average 

 maximum temperature (°C) 

average minimum 

temperature (°C) 

average  hours of sunshine 

per day 

average days withprecipitation 

per month 

average mm precipitation 

per month 

average sea 

temperature (°C)

January  5  0  2  20    n/a 

February  6  0  3  15    n/a 

March  10  2  4  20    n/a 

April  13  4  5  18    n/a 

May  18  8  7  18    n/a 

June  20  10  6  19    n/a 

July  22  12  7  17    n/a 

August  23  12  7  17    n/a 

September  19  10  5  18    n/a 

October  15  6  4  19    n/a 

November  9  3  2  21    n/a 

December  6  1  2  21    n/a 

 = 0­5 mm ●   = 6­30 mm ●   = 31­60 mm ●   = 61­100 mm ●   = 101­200 mm ●   = over 200 mm 

Source: http://www.whatstheweatherlike.org/netherlands/tilburg.htm

I checked were the sun is during winter and summer with an app on my mobile phone. During

winter the sun only reaches the most northern part of the open area, in high summer the sun

reaches almost everywhere with the most sunshine in the northern part of the open area. This is

where the most sun demanding species will be planted.

Soil: Exact measurements on pH I did not do but from the site itself it is clear

that the soil is very sandy, poor in nutrients and acidic. The forest

surrounding the open space still contains the typical podsol, leached out

topsoil. On the open space itself there are indicator (pioneer) species

growing like Pinus sylvestris and Betula pendula. On several spots I did a soil test with some soil in a glass jar and shaking it

and let it settle for several hours. On the right you can see the result.

Practically all sand with very little organic matter. The result was the same

for all the 5 samples I took.

The groundwater level is around 3-4m below the surface.

Zonation:

Zone 1: This zone will be the central zone where most of the activities are. There is a storage place

made of a sea container for equipment. A herb spiral and vegetable garden beds can be made

here. This is also the place for the teagarden. From the container an extra roof will be made to be

able to catch rainwater and store in one or two IBC containers.

Zone 2: On the border between the first and the second zone there will be a lot of lime trees that

can be coppiced. The leaves can be eaten and the drop will be used as green manure and because

of the high mineral content be used against acidification of the soil.

In this zone most of the grafted species are planted. Also sea buckthorns are added as nitrogen

fixer. Shrub species are mainly Ribes and Rubus spp. But this can be extended.

Zone 3: Here all the nut trees are situated. Italian alder is added as a nitrogen fixer, together with

lime trees this should improve the soil a lot during the years.

Zone 4: This zone is used as source of wood to be chipped or to be used as stems to grow

mushrooms. Some oaks are growing here, nuts can be used to make oak meal.

Zone 5: This zone will be left unmanaged.

Working plan

The first phase will take place this year. As soon as possible nitrogen fixing annuals will be sown like

Black medick (Medicago lupulina), lupine (Lupine spp) and

comfrey (Symphytum spp). Black medick is especially good since it

makes very deep roots, taking up minerals. Clovers don’t like an

acid soil, can be used later in the process.

A 20 foot sea container will be placed for the storage of all the

equipment and other materials. The container is placed in the

north eastern corner because there the surrounding trees are

lower for the water catchment and there is some sun because of

that but not too much. Also the roof will be extended so you will

get a space to hide for the rain. A gutter will be installed to catch

the rain in one or two IBC tanks of 1000 liter. With this amount of water it should be possible to

water all the plants and trees taking into account that it rains almost throughout the year.

The roof area will be around 6x6=36m2, with annual rainfall of 800mm there will be around 28.000

liters collected from the roof. Excess water can be led into a wadi (not a swale since there is no

slope) just next to the container were it can infiltrate into the ground.

The soil is poor and acidic. The soil needs a lot more organic matter. If money allows it a large

quantity of compost can be brought in. At the moment there are a lot of young pine and birch trees

growing in the open area.

In the fall those trees will be removed and also

some trees in the surrounding area will be cut

(pines and birches), mainly to get some space for

the walking paths. For one day a wood chipper will

be rented to make woodchips out of the wood and

this can be used on the pathways and surrounding

newly planted trees. The pathways can be seen in

the image to the right. The grey ones are to be

made and the road will be kept in place. The road

can be sown with clover and grass as groundcover.

The path to the left will lead to the actual

“Groeilokaal”. The path from below is the entry for

visitors coming from the bicycle path.

Lime will be added when the land is cleared, exact measurement and calculation of the amount

needed still needs to be done.

When the land is cleared and the paths are in place, during (early) winter time the first trees of the

canopy layer of the food forest can be planted. In the map below you can see where all the trees

are planned.

Out of paper I cut circles in the right proportions to resemble what the ultimate size of the trees

will be, this to ensure that there is enough light for the other layers below. All sizes and

information of the species are taken from the book “Creating a forest garden” by Martin Crawford.

A list of species can be found below. Between brackets to clarify what species on the map. This list

is not inclusive as there are many more edible species to be discovered.

Crown layer:

Fruit:

Sweet cherry, Prunus avium 8m high, 6m wide

Plums, Prunus domestica 6-7m high and wide

Pears, Pyrus communis 8-20m high, 8m wide

Apples, Malus domestica 4-5 m high and wide

Hawthorns, Crataegus spp, 4-6m high, 4m wide (partly grafted with Medlar, Mespilus germanica)

(HAW)

Service tree, Sorbus devoniensis, 6m high and 4m wide

Sea Buckthorn, hippophea spp, 3-4m high and 5m wide (Sea Buck)

June berries, Amelanchier spp, 5-6m high, 3-4m wide (AME)

European Elder, Sambucus nigra, 46m high and wide

Nuts:

Hazels, Corylus spp, 5-6m high and wide

Walnut, Juglans regia, 20m high, 15m wide

Oak, Quercus robur, 20-30m high and wide (already present)

Sweet chestnut, castanea sativa 15-20m high, 10-15m wide

Pecan, Carya spp., 6m high and wide.

Nitrogen fixers

Italian alder, Alnus cordata, 20m high and 6m wide (ALNUS)

Sea Buckthorn, hippophea spp, 3-4m high and 5m wide

Leaves:

Lime, Tilia spp, 4m high and wide if coppiced, also good green manure. Some will not be coppiced

as a source of flowers for tea.

Shrub layer

Together with the canopy layer also the shrub layer can already be planted. I did not make a

detailed map (yet) of all the shrubs, most of them will tolerate shade, but perform best in the sun.

Ribes spp, are quite shade tolerant, planted mainly in zone 2

Rubus spp

Other layers

In a real food forest there can be as much as 7 layers but to sort all the species out and design

them in the system will take too much time for this PDC alone. There are too many species to

choose from and give a place in the 4000 m2. Also the establishment of the trees will take some

time and to create the necessary microclimates for the different species. This is also best done by

observing the coming years how the system develops.