Ring Beam Gardens -an update

Peter Morgan 2015

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Ring Beam Gardens - an update

Ring Beam Gardens are small fertile gardens encircled by a ring of bricks – to define the area. They

were originally designed to act as gardens for the Arborloo toilet, once they were filled and covered

with soil, as an alternative to planting trees. The ring beam forms part of the Arborloo - normally a

ring of bricks on which the toilet slab is mounted. However, it has been found that these small gardens

– normally about one metre in diameter can be very productive. The production of green vegetables

can be remarkable considering the area of the garden, especially when given a plentiful supply of

nitrogen – dilute urine being a source which is commonly available. This current work tries to carry

this concept further by trying to save on the amount of water used to irrigate the small garden, by

using an underground watering system, a plastic sheet to reduce loss of water to deeper soil and also

the familiar use of mulch to reduce loss of water by evaporation and protect the surface of the soil.

The experiments described here were undertaken in round and rectangular ring beam gardens, with a

variety of food-plants. Ring beam gardens have been researched earlier by Aquamor, and whilst their

area is small their productivity can be considerable. In this case the rectangular bed has also been

described as a ring beam garden, as it is made and used in the same way as the circular ring beam. In

each case the bed area was dug down to about 150mm, surrounded by bricks and then a plastic sheet

matching the area placed on the floor of the bed. Another method is to make the brick ring beam first

and then dig down inside the bricks. A mix of compost and topsoil is then added to half fill the bed.

Then a simple sub-surface watering system is put together. This is made from a ring of plastic pipe

with a plastic tee piece placed somewhere in the ring. The vertical member of the tee is fitted to

another short plastic pipe which is fitted to a water bottle with the base cut out. A series of holes are

drilled into the lower part of the pipe. This ring is laid on the soil already in the bed. The bed is filled

up to 150mm depth with further soil, mixed with compost.

A range of chosen vegetables and food plant seedlings are then planted and the levelled soil covered

with a mulch of drying leaves. Initial watering of the seedlings, over the whole bed, was performed

with a watering can fitted with a rose. When the plants were established and the roots penetrated

deeper into the soil, the sub-surface watering method began. The addition of a shade cloth over the

vegetables reduced water loss in hot weather.

The concept is simple and far from new. The wastage of water is reduced – first by reducing

evaporation from the soil surface by mulching. And second by applying the water below the surface of

the soil – further reducing evaporation. And third, reducing the loss of water to deeper layers beyond

the root zone by laying thin plastic sheet within the beds.

In these trials diluted urine was used as a source of nitrogen and applied in a diluted form beneath soil.

This lowers the loss of nitrogen, when compared to application on the soil surface. It is known that

most green vegetables respond well to nitrogen applied in the form of diluted urine. A variety of green

vegetables have been tried in previous trials (rape, lettuce, covo and spinach). The concentration of

urine used was around 1 part urine to 8 parts water (3 jam jars of urine (1125 litres) in a 9 or 10li

bucket of water. The smaller ring beams receiving one charge per week and the larger ring beam 2

charges per week. Normal watering was carried out when the plants shows signs of wilting. The

experiment started 2 months before the rains began, and this period is reported here. In this case sweet

potato was also sown from cuttings and two pumpkins emerged from the soil without being planted.

The pumpkin and sweet potato, which take longer to mature started to dominate the beds after the

rains started. Many green vegetables do not grow well during the rainy season. The early part of the

experiment is reported here.

Peter Morgan

Harare

February 2015

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The effect of diluted urine application on vegetable growth taken from earlier work by Aquamor

Left: One metre diameter ring beam of spinach produced 23kg of spinach in 9 months.

Right: effect of dilute urine application to lettuce.

Effect of dilute urine application on rape (left) and pumpkin (right)

At the school, dramatic effects of the application of dilute urine in ring beams on spinach, rape

and maize and on spinach in beds.

Effect of dilute urine on spinach and rape in basins. Spinach production increased

production by 3.4X and Rape production increased 5X.

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Construction of round ring beam gardens

Two existing 1m diameter ring beam gardens were used, the soil being dug out to 150mm below the brick ring. A

mix of compost and soil was prepared. Thin plastic sheet was then prepared to cover the base of the circular

excavation.

75mm of the compost soil mix was then added to the base of the excavation. A ring of 25mm black poly pipe was

then prepared to make a ring held together by a poly pipe tee piece. The length was adjusted according to the size of

the ring beam garden – in this case 2.2m. The upright of the tee piece led to a plastic bottle held above soil level in

which irrigation water was poured. A series of 8mm holes were drilled at 150mm intervals in the lower part of the

circular pipe.

The circular water feed pipe was laid above the soil (75mm deep) and a further layer of soil (`75mm deep) was laid

over the pipe. A discarded plastic water bottle was the fitted to upright pipe ascending from the tee fitting. Water is

fed through this bottle when the bed is watered underground.

Planting and watering

After watering with a can fitted with a rose, the seedlings were planted. In this case cuttings of sweet potato. After

planting water was added to the under-the-soil watering system through the bottle with a water can. The circular

bed was then watered further and a leaf mulch added. A second bed of lettuce was planted and a mulch added.

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Construction of rectangular ring beam garden

A suitably placed rectangular hole was dug measuring 1.2m x 2.8m and 150mm below ground. This was surrounded

by bricks mortared together. Excavated soil was place around the brickwork to make it secure.

As with the circular beds, thin plastic sheet was laid down on the base of the excavation. A 75mm layer of soil

(mixed topsoil and compost) was laid over the plastic sheet.

Preparing the underground water feed

In this case the below-ground watering system was made in the form of a rectangle of 25mm poly pipe about 2m

long and 0.6m wide with a tee piece at both ends pointing upwards. Holes were drilled (8mm) at 150mm intervals on

the under-side of the pipe.

At one end of the underground watering system a 9li bucket was modified by cutting a hole and then securing a

25mm plastic connector through the base. A tea strainer made with stainless steel mesh was then bonded to the

inside of the bucket above the connector. The strainer held back any items then might clog the holes in the water

delivery system.

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After the underground water delivery system had been put into place, another layer of

soil/compost mix was added over the piping (75mm deep).

Planting

Water was applied with a watering can fitted with a rose to half the bed and then sweet potato

cuttings were planted on 10th October 2015.

Further seedling were planted – spinach, rape and onion (within the sweet potato bed) into the

bed on 17th October 2015. A leaf mulch was used to cover the entire bed.

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Progress of the vegetables in beds (pre-rains)

Sweet potato. Planted 16th October (left) and on and 11th November (right) .

Lettuce. Planted 17th October (left) and on 11th November. 2014. Note pumpkin emerging from the bed.

The growth in the bed on 11th November (left). Spinach, rape, sweet potato and onion (hidden). Photo on right taken

on 18th November one day over a month of planting seedlings. Some of the spinach had already been harvested.

Below the ground watering started on 11th November – pre-rains. Considerable growth only a month after planting.

A pumpkin is also arising within the rape. Later it would dominate the bed like the sweet potato.

As can be seen, a considerable growth of green vegetables had taken place a month after planting and

during the drier period of the experiment. Once the rains began, the vegetable growth increased at first

and then decreased, when pumpkin and sweet potato started to dominate. The cropping time for sweet

potato and pumpkin is about 3 to 4 months. Both spinach, rape and covo can be cropped regularly.

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Growth after rains with added dilute urine.

Light infrequent showers started in October, becoming heavier in late November and heavy in

December. Regular watering was required during October and much of November. However extra

water was required during several dry spells, when the loss of turgor in the plants became evident.

Diluted urine treatment continued once a week, using a method outlined earlier. What became clearer

as the plants grew more rapidly, was that each plant species reacted differently from watering and

urine treatment. In mixed beds the pumpkin and sweet potato seem to dominate. As the rainy season

progressed the green vegetables seems to suffer (not an unusual response to green vegetables during

the rainy season) and the sweet potato and pumpkin started to dominate.

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Photos of post rain period.

During December the spinach, covo and lettuce were productive, but with increasing dominance of sweet potato and

pumpkin.

Later in the rains during January, the sweet potato and pumpkin seemed to dominate.

By February, some ring beams had disappeared from sight, being dominated by growths of sweet potato and

pumpkin. Many young pumpkin died, but amongst them rather fine specimens prevailed.

At the time of writing in mid-February, the 4 ring beams under study revealed a weakening green

vegetable population and strengthening sweet potato and pumpkin population. And much room for

thought about the next stage of the experiment. I thank Oswald Chakauya who has faithfully helped

me with this gardening project.

An update will be posted at the ends of the rain, in about April – May 2015