Plant Systems — by Geoff Lawton September 23, 2005
At 400 meters below sea level, the Jordan Valley is the lowest piece of land in the world. Its climate is very dry with an average rainfall of 150 millimeters a year, most of which comes in 2 or 3 mid-winter events. Summers are very hot with day time temperatures often reaching 50 centigrade with hot nights often over 25 centigrade. Winters are warm with no frost.
To achieve a healthy population it is unlikely that ordinary people will be able to afford full nutrition if gardens are not plentiful throughout the local settlements.
The house is an integral part of achieving a plentiful and productive garden design. It should be comfortable to live in, make efficient use of energy, and be inexpensive to operate. There are generalizations that can be made, but the essential design features required for a house in the Jordan Valley to perform efficiently in a passive way are quite specific.
- No Jordan Valley house should be planned or built without its integral trellis and garden, as these may not only save most or all energy usage and cost of air conditioning, but also provide food and shelter. The attached shade house in particular must be planned as integral to the house design and in fact, as the summer living area and kitchen. For this reason, the winter kitchen or indoor kitchen must open onto the shade house summer kitchen.
- The house itself needs to be elongated east to west so that the shade that is cast on the north side is long and the heat gain on the west wall is small. While still permitting the low winter sun to enter the rooms through the south side windows, it is the roof overhang that excludes the summer sun from hitting the walls and windows.
- The whole roof area should be completely shaded with a thick vine trellis, when ever possible. This insulates the roof, greatly reducing the heat gain of the house, making it cooler and more comfortable to live in. It also greatly increases the usable area of the house as the roof, once fully shaded, will become a very comfortable area open to breezes. Roofs have been traditionally used in many cultures for multiple uses.
- Down drafts can be created with sails, slats, wind scoops and wind chimneys on roof areas, either fixed or self steering to force a down flow of the constant or prevailing winds. At their outlets in rooms, these down draft inlets can be fitted with damp hessian, damp trays of charcoal or unglazed pots full of water. These add considerable cooling capacity to the air and humidify the air inside the house.
- Houses can be constructed so that they assist other houses, placed close together with the long axis of their street east west. A common or close-spaced wall ensures that neither wind nor heat can easily penetrate the settlement. If all houses are sun facing and of more than one storey in height, cool air in shaded narrow streets and courtyards is always available and vents at roof level will draw cool air into the rooms of the houses. The bottom floors and flat roofs are used for living and the upper floors and roof areas are for bedrooms.
- No windows on the west facing wall of the house
- The west facing wall should be painted white to reflect the late afternoon sun
- If possible the west-facing wall should also be fully shaded with a deciduous vine trellis such as grapes, which will lose their leaves in winter and allow some extra light in during the cooler time of year
- This west-facing wall vine trellis can, if possible, be incorporated into a courtyard design, with vine trellis above, and a small fish pond below. The light that is reflected from the white-painted walls creates a very comfortable private area in which to sit.
- Evergreen trees should be planted to the west of the house to add to the shading and cooling of the house
- Place a cool air source on the north side of the house in the form of a fully enclosed shade house created with thick vine trellis or shade cloth, if available. On the ground, add bark, leaf mulch or small stones to a depth of 150 millimeters, so that this area can be easily kept damp and cool on the shady north side, using very little water. This area is a source of cool air that can be vented into the house as a natural air conditioner and also makes a very comfortable outside kitchen and sitting area in summer.
- A very simple sun chimney should be fitted to the south side of the house roof as the source of suction to pull the cool air through the house. This is made from a 150 mm diameter thin metal pipe 3 meters long, painted mat black with a rain cap on the top and an insect screen on the bottom. This pipe is then fitted to a hole made in the roof, connecting through to the ceiling of the hottest room on the south side of the house. This 3-meter sun chimney will need some form of bracing so that it does not blow over in the occasional strong seasonal winds. On hot days when the house is most uncomfortable, the hot sun shining on the mat black metal pipe will make it very hot, heating the air inside. This air will rise up the pipe, sucking the hot air from the house.
- Close all windows and doors except the door leading to the cool shaded area on the north side of the house. The cool air is pulled into the house creating a comfortable living space with no energy cost involved. Uninterrupted air flow is very important. The total cooling effect can be greatly increased if unglazed pots full of water are placed in the air flow, as the evaporation cools the living space further.
- The west side of the house should have no windows because the low westerly sun is the greatest source of heat in the house.
- The east side can have small windows. It is best if they are partly shaded with about 50 percent, full-length shade cover.
- The north side has the cool shade house attached and only needs access with small windows and some form of insect-screened venting close to the floor for the cool air flow input pulled by the solar chimney on the south side.
- The south side, facing the sun, should have no more than 25 percent of the total wall area in windows and should have overhanging eaves of at least half a meter wide to protect from mid-day mid-summer sun.
- External, rather than internal blinds prevent most heat entry through windows. These can be made of wood, aluminum, or cane matting and rolled up under the overhanging eave when not needed.
Long term health and good nutrition for can be achieved for the family through home gardens. This is especially important for children, as alternative sources of food are often of poor quality or contaminated with toxins. Imported food is expensive, not as fresh, and is often of poor nutritional quality. Locally grown field crops are usually treated with large amounts of chemical fertilizer and biocides and are often sprayed with domestic aerosol insect spray while waiting to be sold in shops.
To relieve this, the home garden, rather than field crops, is our primary strategy for good health. A mixed garden of vegetables, herbs, fruit, and small animals produces all the essential minerals and vitamins needed and can make every family self reliant. The garden must be planned very seriously if it is to be successful and to be so, it must not only be very productive, but must also continuously increase in soil fertility and produce with less and less effort over the first 10 years. This is possible and quite easily achieved if you follow the instructions below carefully.
- Mulch is the most important ingredient in good garden design and it is the one element that is completely missing from almost all local gardens. Yet a well mulched garden (100 to 150 millimeters thick) uses 1/10 the water of bare soil. That is, bare soil gardens use 10 times more water to produce the same volume of crops. Garden beds need to be completely covered in thick mulch continuously, so mulch will need to be sourced locally and eventually produced locally in surplus, which can easily be achieved.
- It is important that the garden be well fenced for its protection from many different types of local foragers.
- Vegetables can be produced on slightly raised garden beds using many different materials for the edging, such as stone, concrete blocks, logs, and banana trunks. Mud bricks also work very well as they absorb some water and insulate the garden bed, cooling it down and reducing its water requirement. Mud bricks are also very cheap to make and are a traditional local technology that is well understood.
- For best results, all vegetable gardens will need to be at least 75-percent shaded. This can be done individually with shadecloth, palm fronds, or tree branches on frames 1 to 1.5 meters high. Alternatively, solid pillars of concrete blocks, wooden posts, steel posts or mud bricks to 2.5 meters can be used to produce permanent vine trellis crops over most of the garden. Grape vines trellises with overhead spacing of 1 to 2 meters will shade a vegetable garden very well, relieving excess sun burning and water stress.
- The east side of the vegetable garden needs to have a vertical or angled out trellis with 300 millimeter spacing of uprights and horizontals that can be densely planted in productive crops of climbing vegetables, tomatoes, cucumbers, beans, gourds etc. This will protect the garden from the early morning sun which can dry the moisture left from the cooler night-time temperatures. This will keep the garden cooler for longer at the start of the day and reduce overall water stress.
- The west side of the garden needs vertical or angled out trellises with 200 millimeter or less spacing of uprights and horizontals covered with a very dense and very shady planting of thick fleshy vines, as great heat can build up in the late afternoon and cause severe water stress.
- The north side does not need a vertical trellis and can be left completely open, as this is the shady side and receives no direct sun.
- The south side should have a vertical or angled out trellis with wide spacing of 1 meter, with uprights only, and planted with a productive climbing vegetable crop.
Increasing soil fertility
To insure that garden fertility is continually increasing, the following steps should be taken:
- The continuous additions of mulch will allow a steady increase in the fertility and productivity of the garden. Many different materials can be used for mulch but most importantly, all crop residues produced from the garden must be returned as mulch to the garden. Additions of leaves, weeds twigs, kitchen food scraps, cotton clothes, wool, small branches, rotten wood, bark, wood chips, saw dust, paper, card board, hair, feathers, skins, and bones are all organic materials that will decompose into high quality organic black humus. This will greatly increase soil fertility and water holding capability, if added to the surface of the soil in high enough quantity (100 to 150 millimeters deep),.especially if some animal manures are incorporated in the mix. Mulch needs to be absolutely soaked initially. After that, slight additions of water daily will help retain good moisture for both mulch decomposition and crop growth.
- Any design feature that can increase the amount of mulch the garden can receive will potentially increase the garden’s soil fertility. Areas of the garden can be maintained as mulch pits. They should be kept full and piled as high as possible so that the mulch is continuously rotting down to a high-quality black organic humus. These mulch pits become very fertile to plant around and after a few years become very fertile circular vegetable gardens. Animal waste in the form of meat, fish and even whole dead animals can be buried deep in the mulch pits at least half a meter deep. This will quickly decompose, and speed up the decomposition process of the surrounding mulch.
- The garden should be continuously growing crops and never be left empty. This is essential in creating ongoing increases in soil fertility and in providing shade to the soil.
- It is important to design the garden so that beds are not walked on. Walking on the vegetable growing bed causes soil compaction and greatly reduces soil fertility and productivity. Therefore, beds must be designed so that footpaths allow access to the entire vegetable- growing area. The widest you can have a good productive vegetable garden growing bed is twice the length of your arm. A footpath on both sides of the bed allows you to access the entire bed-by reaching halfway into the bed from either path. This is called a double-reach row bed. Once you have this design in place, there is never a need to walk on the garden bed where the crops are grown.
- In the original construction of the garden the garden must be shaped so that it will hold water and can be flooded to a depth of 100 to 150 millimeters of water. This is important so that the water will sit in the bed before it soaks in. This same shape and space will also hold the mulch 100 to 150 millimeters deep and will hold the mulch and water at the same time.
- A diversity of crops should be planted that are appropriate to the season. They should be completely mixed in the planting bed as much as is practical, with mixed perennial herbs around footpath edges and corners. Rosemary, oregano, mint, chamomile and many more herbs are traditionally grown and used locally. When incorporated into the home vegetable garden, they not only confuse and distract pests they also add stability and increase fertility.
- All vegetable garden growing beds should have a regular succession of bean crops. This will help maintain soil fertility, as these legumes add nitrogen to the soil. Broad beans and peas should be grown in winter, and bush beans, tropical beans and snake beans in summer.
- All waste-water except that from the toilet must be directed to the garden. If natural cleaning soaps are used in the house, then all shower water, wash basin water, kitchen sink water and water used to wash floors is good for the garden; in fact the average volume of water from these sources that would otherwise be wasted per person will grow the food for that person if gardens are well designed and deep mulches are used.
Fertilizer can be made by mixing mulch, manure and soil. First, mix 9 parts mulch with 1 part manure. Manures vary in strength with the strongest being pigeon then chicken, turkey, duck, goose, rabbit, cow, goat and sheep. The more variety of manures and mulch materials that are used, the better the potential soil fertility. Next, mix fine soil in with the mulch manure mixture at about 1/20 fine soil to 19/20 mulch manure mixture. After applying this mixture to the garden, add a layer 10 millimeter thick of fine soil on top of the mixture.
Fruit trees that are often grown in local gardens include date palms, olives, figs, guava, pomegranate, grapes, citrus, carob, mango, white, black, and red mulberries, loquat, banana, papaya, fruiting cactus (Tuna spp), sugar cane and a local fruit tree called dom (Ziziphus spinachrista spp). Sometimes custard apple, zapote and apples are grown and many more would be worth trying. Henna trees are also often planted for use as a hair dye
All fruit trees benefit greatly from deep mulch surrounding their trunks but not touching the trunk. Tree mulch is constructed exactly the same as vegetable garden mulch with the same water holding soakage beds around the tree trunk, though it can be rougher and contain larger material. It should be placed in a circle from 25 millimeters away from the trunk out to the outside drip line from the tree canopy, and should be applied in a thicker layer than vegetable mulch—200 to 500 millimeters thick. Animal wastes or carcasses such as road kills can also be buried, under newly planted trees, adding a slow release organic fertilizer to the new planting.
An excellent way to help tree mulch to retain moisture is to plant succulent ground covers like pig face (Mesembryanthemum spp.) and sun jewel on the inside and the outside of each tree mulch circle. These succulent plants become living ground covers that insulate the soil.
Included in many gardens are many varieties of legume trees which are often known for being good forage for animals. Though it is not widely known, these trees act as natural organic fertilizers to the soil if their leaves, seeds, seed pods, twigs and rotting wood are allowed to remain on the soil as mulch. In addition, leguminous trees can be planted in close association with mixed fruit trees. Large amounts of natural organic nitrogen are released from the roots deep in the soils, which then become available to the fruit trees, especially after being cut back. When these trees are cut for animal forage or for mulch many of these trees will re-grow so that they continuously produce mulch, animal feed and soil fertilizer. If cut back at the right time of year–with the very first light rain of early winter to mid-winter, they open up the garden for extra winter light and warmth when it is needed. After this, all cutting must stop for the trees to recover and be able to provide their much needed summer shade.
The most functional of all these trees grown locally is Leaucaena, but Albizia lebek and Tipuana tipu are growing in some locations. Prosopis is very common and is very hardy but is very thorny as is the local legume tree jerusalem thorn (Parkinsonia spp), Poinciana is also grown in many gardens but it is a little bit slow-growing to be used as a cut mulch tree and is better as a shade legume tree and fruit tree-associated plant. There are 2 types of Acacia grown locally and a Casuarinas. These are good soil nitrogen-producing fruit tree-associates for adding natural organic fertilizer to the soil but are not good at recovering from cutting.
In the Jordan Valley there are quite a few Eucalyptus that have been planted, and some are very large. This tree produces a substance that makes growing other trees around it very difficult, and so should be avoided in home gardens.
A good quality of life can be achieved by the average person engaged in a sustainable relationship with nature by following these recommendations for house and garden design in the Jordan Valley.Comments (3)