school – University of Bristol Botanic Garden

By Jacqueline Campbell

Connections are often established in the most unexpected manner. How many times do you come away from a situation thinking “it’s a small world”, where just the opportune mention of a single word or phrase strikes a chord and is enough to foster new links and an avenue by which to share new ideas.

As unlikely as it seems, the words “pond mud” brought the Red Maids’ Schooltogether with the University of Bristol Botanic Garden recently. And from this link, students at the school have gone on to create their own miniature sustainable ecosystems using mud gathered from the garden’s mature and established ponds.

Marvellous muddy mesocosms

Mrs Turner, Head of Biology at Red Maids’ School, studying
the mesocosms.

Sixth Form students following the International Baccalaureate biology curriculum are required to complete a number of practical experiments. One of these is the creation of a mesocosm known as a Winogradsky column; essentially a self-contained, sustainable ecosystem grown in a sealed plastic bottle under controlled conditions.

A critical element of this experiment is pond mud. As they are situated no more than a couple of miles apart, the Red Maids’ School approached staff at the Botanic Garden for their advice and assistance in setting up such an ecosystem. A number of phone calls and a few visits later, two groups of students have used pond mud sourced from the Botanic Garden and are watching to see the bacteria in their stratified ecosystems develop.

The mesocosms in this image are just a few hours old.
Images are taken every two days to track and record the changes
over time.

The mesocoms now live on a sunny window sill in the Biology Department at Red Maids’, and are a constant source of curiosity to all. Despite a little reluctance mainly associated with the smell of pond mud, the students involved are thrilled to have created their own ecosystems and are often now found enthusing about the colour of their bacteria and amount of respiration they can see.

Images taken every two days are providing a good record of how the ecosystems are developing over time. From an initial cloudy but uniform situation, clearly defined layers are forming coupled with a notable increase in the pressure within the bottles showing the incredible amount of respiration that is occurring within the system.

Bacteria of many colours

Students have seen the pressure within their ecosystems
increase over time thanks to the highly visible levels of
respiration occurring within the sealed environment. A range
of different coloured bacteria are also now present.

The ingredients required to create the Winogradsky column are: pond mud, shredded newspaper, crushed egg shells and raw egg yolk. Pond mud provides a suitable base while the newspaper, egg shell and egg yolk provide sources of carbon, carbon dioxide and sulphur respectively. As a first step, these components are mixed together and poured into the bottom of a plastic fizzy drinks bottle.

On top of this layer comes another of compost, followed finally by some pond water. The idea is that many different coloured layers of bacteria develop, and each of these transforms molecules for the others to use. And as long as there is light entering the system, the column should theoretically continue to maintain a healthy microbial ecosystem for many months.

Waiting to develop: Over time, students at Red Maids’ hope
to see their Winogradsky columns develop into a stratified
system. This will provide a visual example of various modes of
metabolism and zonation in the microbial world. The
mesocosm shown in this image is several months old.

Conditions at the bottom of the column are highly anaerobic with a high sulphide concentration ideal for the growth of sulphate reducing bacteria, green sulphur bacteria and purple sulphur bacteria. Moving higher in the column, with conditions becoming more aerobic and a reduction in sulphide concentration, we can expect to see the development of purple non-sulphur bacteria, iron-oxidizing bacteria, heterotrophic bacteria and cyanobacteria.

Of course none of this would be possible without the kind assistance of the Botanic Garden staff, who waded into freezing winter waters to collect the mud. The Red Maids’ School is very grateful to have established this connection, and hopes that it too will blossom over time.

Dr Jacqueline Campbell has a PhD in physics from St Andrews University and twelve years of editorial experience working for the Institute of Physics Publishing and as a freelance journalist. She now works as a science technician at the Red Maids’ School.

By Helen Roberts

A keyhole garden in Rwanda.
Photo courtesy of Send a Cow.

Back in June, my son’s primary school, located in a small village on the edge of the Mendip Hills, built something called a keyhole garden in their grounds. Having no idea what a keyhole garden was, I thought I would offer up my services as a parent volunteer for the garden day.

The idea of keyhole gardens originated in Africa out of necessity. They enable families to produce food on dry, exposed and rocky soils – essentially land that is infertile. The gardens are shaped like a keyhole and act like an organic recycling tank using food and garden waste as fuel to grow vegetables.

The garden day at my son’s school was organised and facilitated by a charity organisation called Send a Cow. This charity helps families and communities in Africa by providing farmers with the skills and tools they need to farm using sustainable and organic methods. Farmers on the programme are given the gift of livestock, seeds and other assets and every farmer makes a pledge to pass on the gift of training, seeds and livestock to another family in need.

The facilitators from Send a Cow held a morning workshop with the children to discuss building the keyhole garden and the materials needed. Two sixth form pupils from another local school were there to help with the session and contributed enormously to the discussion, engaging with their younger peers and getting them interested in the activities. These two students are hoping to run Send a Cow African Garden Day workshops themselves.

A tip tap hand washer in Uganda.
Photo courtesy of Send a Cow.

Some of the children also learned about tip tap hand washers. These are a simple water conserving/hygiene device used in African countries aimed at improving hygiene and preventing the spread of diseases. Send a Cow shows families how to make them.

Laying the foundation

I joined the children in the afternoon to help build the garden. My pre-schooler was eager to muck in too as he is an avid gardener and had already donned gloves with trowel in hand in eager anticipation of the job ahead!

The keyhole garden was to be located along a major walk way, on a patch of grass that would be visible to the children walking to their various classes. This would enable them to see what was happening with the garden on a day-to-day basis and judge whether the garden needed weeding or watering. A group of children were assigned the task of building the stone base around the patch of bare soil that had had the turf removed the previous week. This turf was recycled back into the garden via the school compost bins.

The foundation of the garden can be made from
whatever resources are available. This garden is in Lesotho.
Photo courtesy of Send a Cow.

The prepared ground was a typical keyhole shape, with a 1.4 metre radius circle and an entrance triangle starting from the circle centre to the edge of the circle. The entrance is north facing to allow more room for sun-loving plants. The children worked hard moving and placing stones in a double layer for the outer wall- a little taster of the backbreaking work done by people who build dry stone walls.

For all key hole gardens, the simplicity of the design means materials can be sourced locally. In Africa, this includes many creative construction materials, such as plastic bottles filled with sand, instead of stones or bricks for the main structure of the key-hole garden base. We used Mendip limestone.

After the stonework, a steady flow of soil mixed with manure was wheel-barrowed across the school grounds and excitedly transferred by spade into the garden. The children had previously made the composting basket, which is central to the keyhole garden, out of runner bean canes (or sticks), string and chicken wire. This was placed in the centre whilst the soil was piled around it. Composting material was then placed in the compost basket, along with straw.

Planting it up

The finished garden at the primary school.

Planting up the garden was the most exciting part for the children. The volunteers had a line of seedlings lined up for the students to plant carefully. Typically, the vegetables commonly grown in African keyhole gardens include spinach, amaranth, gourds, Tithonia (eg tree marigold), chillies, sweetcorn and climbing beans. Plants with deep roots that require lots of feeding are planted near the centre of the garden. Herbs are added near the rock walls to help bind the soil and compost.

In the Mendip school garden, tomatoes, lettuce, cabbages, peas, sunflowers, cornflowers, nasturtium and calendula were planted out. Flowers were added to the vegetables to add colour and other benefits. Nasturtiums are useful companion plants because black aphids, black fly and cabbage white butterflies cannot resist them and feed on them rather than the crops.

“It was a fantastic day and the children really enjoyed it and still talk about it avidly,” said Mrs Savage, the school reception teacher.

The African Garden Day informed the children about positive ways people in Africa are feeding themselves sustainably, but it’s also a long-term teaching tool and resource to get children interested in plants.

“All the summer sunshine has done wonders for the African Garden created by the children last term,” said Mrs Williams, the school’s Head Teacher over the summer. “It is looking amazing and we are very proud of our achievement!”

There are plans afoot to develop a second garden, but more in keeping with Somerset traditions using weaved willow to form the base wall and compost bin.

African Garden Days is one of many programmes run by Send a Cow. It is the UK’s largest global learning project with approximately 30,000 children taking part. African Garden Days offers primary schools the chance to experience a fantastic hands-on day, combining classroom sessions with an outdoor challenge to create a global kitchen garden within the school grounds. It is aimed at Key stage 2 and 3 children, but also involves the whole school in an assembly and class session. The cost of running the garden day goes directly back to Send a Cow.

Category: school

Mud, glorious mud