Part 1 – Stratospheric Ozone Depletion
Part 2 – Loss of Biosphere Integrity
The biogeochemical flows, this planetary boundary is referring to, is the phosphorus cycle and the nitrogen cycle. These cycles happen naturally in nature over time, and without our intervention, remain in balance.
Let’s start with nitrogen
Nitrogen makes up 78% of the air we breath and so, it is all around us. This gas is made of two atoms with triple bonds. These bonds are very difficult to break. Plants and animals, including us, need nitrogen to survive. We cannot use the nitrogen in the air and neither can plants. So how do we access this nitrogen?
Tiny microscopic bacteria that live in the soil take nitrogen from the air and fix it into the soil. These bacteria produce enzymes that break these triple bonds and put nitrogen into a form that is accessible to plants. We can then access our nitrogen requirements by eating the plants. Nitrogen is returned back into the system when plants and animals die or when animals urinate or produce manure. Plants take this nitrogen up from the soil to grow. There are also special bacteria that convert this accessible nitrogen into atmospheric nitrogen or nitrogen gas. Another name for this gas is dinitrogen.
Commercial agriculture uses synthetically made nitrogen to fertilize crops but this chemical leaches into rivers and lakes when it rains and causes algae blooms. When the algae dies, bacteria break them down but consume all the oxygen in the water by doing so. These oxygen consuming bacteria turn the river or lake into a dead zone. It’s called a dead zone because no other aquatic life can survive in water without oxygen. America’s dead zone off the eastern coast is visible from space.
You can see from looking at the planetary boundaries picture, that we have crossed this boundary into the red high risk areas. This means we have too many dead zones around the world because of nitrogen pollution in seas and lakes. Commercial agriculture takes a lot unhealthy shortcuts to produce food but affects the natural balance of nature and thus negatively impacts our ecology. Permaculture methods do not use chemical fertilizers but lets nature do the work for us.
The Phosphorus Cycle
Phosphorus is found in rock especially sediment layers and with constant weathering, is released into the ground. Plants take up phosphorus from the ground and we take up our needed phosphorus from plants. When animals and plants die, this phosphorus is returned back to the soil or runs into the sea, becomes a sedimentary layer and in a few million years, pops up as a mountain exposed to weather again. It’s a really slow process.
Commercial agriculture has messed up the phosphorus cycle so badly, that it is becoming deplete in the soil. Phosphorus is mined and used in chemical fertilisers that commercial farmers use. Permaculture does not use synthetic fertlizers to grow crops and harmonises with nature’s processes. Permaculture is the sustainable and regenerative method of farming because it treats the land as a permanent source of nutrition by building top soil and not depeleting it.
Also known as Keurboom, Tree-In-A-Hurry and Blossom Tree.
This tree is leguminous meaning it is a nitrogen fixer.
Growing Virgilia
The attractive fragrant flowers and the fast growth rate make the keurboom a popular tree for the garden. Of the two, Virgilia divaricata is the better choice as its foliage is more luxuriant, and its growth more compact and it is amazingly beautiful when in full flower.
A keurboom is the perfect tree for the new, bare garden because it grows so fast it will take only two or three years before it will be creating shade, or a screen, and filtering the wind – which is an important consideration in Cape Town suburbs. It is also one of the best species to use as a pioneer in the first stage in the succession to forest. It is happy to grow out in the open, grows fast and quickly and creates the shade that the slower-growing, more permanent trees need to grow in.
Virgilia is propagated from seed. The seed coat is hard and requires some stimulation to initiate germination. Seeds can be soaked in hot water before sowing, or the seed coat can be cracked artificially. They also respond to stimulation by fire and can be treated with the Kirstenbosch Instant Smoke Plus Seed Primer. Seed should be sown in autumn or spring, in well-drained soil at a depth of 0.5 – 1 cm and covered with the sowing medium or milled bark and then watered. Seed can also be sown in situ, e.g. for forest rehabilitation projects. The seeds are highly fertile and can remain alive for many years after they have fallen, even after as many as 30 years they will germinate if conditions are favourable.
Transplant the seedlings after the first pair of true leaves has emerged when they are large enough to handle. Virgilia seedlings grow fast and can be planted into pots or bags for growing in, or directly into their permanent position in the garden. Feed moderately with a liquid fertilizer and water generously. Plant the young trees into a permanent location in full sun or semi-shade. They need good, light soil and plenty of water, particularly during their first 2 to 6 years. Virgilias have strongly spreading surface roots and are greedy feeders; they will benefit from frequent generous applications of compost or organic mulch. Virgilias are sensitive to frost, particularly when young. Mature trees may withstand short periods of frost, but not prolonged exposure to freezing temperatures.
References
- Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, edn 3. Struik, Cape Town.
- Goldblatt, P. & Manning, J. 2000. Cape plants. A conspectus of the Cape flora of South Africa. National Botanical Institute, Pretoria & Missouri Botanical Garden.
- Palmer, E. & Pitman, J. 1972. Trees of southern Africa. Balkema, Cape Town.
- Phillips, E.P. 1928. Virgilia capensis. The Flowering Plants of South Africa 8: t. 305.
- Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
- Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees of southern Africa. Struik, Cape Town.
Giles Mbambezeli & Alice Notten
Kirstenbosch National Botanical Garden
August 2003
Trees are incredible forms of life on this planet.
I can write pages and pages about them. If you knew what I knew about trees, perhaps you would hug them too now and again. They are essential to our existence and without trees, our planet would be inhabitable. I cannot empahsise enough how we must strive to plant them, whenever we can, and in many places as we can.
Just because you don’t have a garden, does not mean you cannot plant a tree. Enhance public spaces like parks and sidewalks with trees. Choosing an indigenous and water wise species will increase chances of survival and not consume too much water.
Here are some important facts you should know about trees:
1. Trees seed rain
Trees transpire water which form clouds and rain back down. Check out these awesome videos which explain the process.
2. Trees increase the fertility of the soil
The leaves that fall off the trees, cover and protect the ground from evaporation. Microorganisms and other small creatures like worms, eat the organic matter and process it into nutritious soil for plants. The oranic matter becomes food for the ground. There are also trees that absorb nitrogen from their air and return it to the soil through their leaf litter and nodes in their roots. If the tree is large enough to prune, the stored nitrogen in the root nodes are released into the soil as the tree balances its roots with its canapy. When deciduous trees lose their leaves in autumn, you can decide how you would like to use them, as they have great fertilizing qualities.
You can choose to rake up the leaves, and store them to make leaf mould. Leaf mould is an excellent form of compost, or you can let nature do all the work for you by leaving them on the ground. Fallen leaves have a wonderful purpose, they protect the ground from extreme cold or heat. Leaves (as mulch) stop water evaporation and when the worms eat them, they turn them into super compost for the soil. This is nature’s cycle of returning nutrients back to the soil so that more life can grow.
3. Trees stabilize the soil
The roots dig deep into the soil to secure the tree and this also protects the soil from soil erosion. Soil erosion occurs when rains fall and top soil is washed away where there are no trees to hold the soil in place. This leaves big gaping holes where it is difficult to grow anything.
4. Trees provide shade and regulate temperature.
If you measured the temperature of various man made things like tar roads, concrete, bricks and steel and then compared those temperatures with the tops of trees, you will see a big difference. Trees regulate the temperature. Man made structures like roads and concrete increase the temperature in cities and contribute to global warming. I am sure all of you have experienced the sanctuary of shade underneath a tree on a very hot day.
5. Trees help in the maintenance of biodiversity and ecosystem balance.
Trees provide a home to wildlife and increase chances of survival of many species. They provide food and shelter. Where many species live together, a balance is retored and is called an ecosystem. An ecosystem can fall out of balance if a species of life is removed and this threatens the survival of all other life. Biodiversity is key for survival of all species.
6. Trees are a resource for fuel and building
Wood from the fallen and dried branches of trees, can be burnt to provide warmth. Burning dried branches also makes coal which can be burnt or used to clean water. It can even clean our teeth! We can make things with wood like furniture, shelter and paper. We must be careful to prune for the trees health, and not cut them down. Destroying a forest for our own needs is selfish when there are better and more sustainable ways of providing for our comforts.
7. Trees store carbon
Do you know about all that carbon in the air that is making our planet hotter and making the sea acidic? Well, it should be in the ground or in trees where it is safe and put to good use. Trees store carbon and return it to the soil by decomposition.
The Moral of the Story
Go out there and plant a tree for Arbor month. Plant 10 trees if you can and try stick to indigenous, water wise trees. Let’s fix the grass deserts in our parks and restore the land, climate and wildlife with trees. Plant some fruit or nut trees in your garden and you will be rewarded with delicious food.
Trees are so vital to our survival. We need more of them to fix the damage we have done to this planet. Plant a tree for Arbor Month.
July is not really a planting month for vegetables, but you can still plant :
– Beetroot seeds
– Cape Gooseberry seeds in seed trays
– Cauliflower seeds
-Celery seeds
– Mint seeds
– Mustard greens/Cress seeds
– Pea seeds
– Potatoes
– Radish seeds
– Shallot seedlings
– Swedes/Rutabagas seeds
– Tomato seedlings
– Turnip seeds
GARDENING TIPS
Now is a good time to start planning your summer garden early in the month so you have enough time to source and purchase open pollinated seeds for early sowing.
Carry out soil tests, particularly on land where growth for one or more seasons has been poor. Here is a link to understand soil tests.
After winter crops have been removed, dig the ground well over and incorporate dressings of organic matter.
Broad beans can be side dressed, earthed up and given support with string or wire if required
Apple trees and grapevines can be pruned to ensure healthy growth.
In mild conditions, tomatoes can be sowed in seed boxes.
Once upon a time,
there was an unhappy women driving home from work. Her name was Hilda. It was late and dark in the evening. Her feet were freezing and the heater in her rusty car didn’t work. She worked long hours and her boss was a mean, demanding man who always told her that he wanted ‘his pound of flesh’ when he wanted her to work late with no overtime pay.
She felt hopeless because she didn’t know how to change her circumstances. She was mentally and physically exhausted and there was not much room in her heart left for extra care.
She didn’t earn very much and could’t afford to fill a basket let alone a trolley when she did her weekly grocery shopping.
One day, she was weeping on the couch and drinking cheap red box wine. Her elderly tortoise-shell cat ,she rescued 8 years ago, sat on her lap and tried to comfort her in his own way by purring and pressing his paws against her in a kneading fashion. He was soft and calm in times like these. Hilda felt grateful for his company and concern.
She heard a knock at the door.
She was too tired for anything and ignored the knocking. The visitor knocked again. This time, the knocking was louder and sounded more determined. She got up and opened the door, and there was a familiar face. It was the neighbour she bumped into occasionally in the road, and also at the local grocery store. Her name from Saffron.
Saffron was holding a big box under her arm and asked if she could come in. Hilda, embarrassed that she was in her pajamas with slippers that were falling apart and a messy house, opened the door for Hilda to come in.
Saffron noticed that Hilda had been crying and drinking alone but decided not to ask about it. Instead, she proudly announced to Hilda that she had opened a seed library. Hilda looked confused.
Saffron enthusiastically explained that a seed library works just like a book library.
You can choose what seeds to borrow, just like you would choose a book that sparks your interest at the library. You borrow the seeds and the library makes a record of what seeds they are. Once the seeds are withdrawn, the lender goes home or to a community garden, to grow the seeds. Once the vegetables or flowers have grown, some are harvested for personal use and some vegetables are left to grow longer. These vegetables that grow longer eventually make flowers and then seeds. The seeds are then collected and dried. The dried seeds are split into two. A small portion goes back to the seed library and the rest can be kept to grow food during the next growing season.
This was all very new to Hilda and without realising it, she started shaking her head. She didn’t have a big garden which was full of overgrown weeds and uncut grass anyway. She explained to Saffron that she didn’t know about gardening and that she didn’t have any space.
Saffron placed the box on the coffee table and opened it.
Inside were lots of small brown envelopes with hand written labels and inside those envelopes were various seeds. Saffron put on her pink glasses that were hanging around her neck and flipped through the little brown envelopes. She picked three out after squinting her eyes at some of the labels.
“I tell you what, Hilda!” she said. “Here are some spinach seeds, they grow in almost anything. I see you have a few pots lying around your stoep with dead plants in them. Try growing some tomatoes and peppers in them. They do well in pots.”
Hilda responded with “Um…” but Saffron interrupted her and said, “Just try it Hilda, it will be good for you. Imagine! If you can grow these easy vegetables, you will never have to buy them again. Gardening is good for the soul!” She wanted to say that it looked like Hilda could do with some therapy and get off the couch but she decided not to. That would be unkind and would do no help in this situation.
Hilda shrugged and accepted the seeds.
Saffron made a few notes in her scrappy book filled with dog ears and coffee stains and suddenly declared that she was late and had to hurry home.
She shut her box abruptly with a loud slam and put it back under her arm. Saffron gave Hilda a firm one armed hug. Hilda almost fell over but managed to regain her balance.
Saffron was out of the door in less than two seconds and Hilda went to the threshold to call “Bye” to Saffron. “Thank you”, she yelled just before Saffron slammed her car door, started the ignition and sped off.
Hilda imagined Saffron on a broom stick with a pointy black hat and then chuckled to herself. Maybe she had too much wine. She caught her reflection in the picture frame on the wall and noticed her teeth were red. How embarrassing, she thought and then went to pour another glass of wine.
A month went by and Hilda left the seeds on the coffee table.
She saw them everyday. About 2 months later, while Hilda was cleaning the house on a sunny Saturday morning, she looked at the seeds which were still lying on the coffee table. She felt a little irritated that they were still there and decided to plant the seeds.
Two weeks later, after locking the front door and rushing to the car, she noticed small seedlings in the ground. She took a few steps back to examine them.
A flicker of excitement lit up in her heart and she felt maternal over the tiny two leaved plants that had poked up through the ground. Some still had seed shells attached to them. It was like a new birth.
She stared at the seedlings in wonder for about a minute and then realised once again that she was late for work. She thought about her new plants during the day and couldn’t wait to get home to see if they grew some more while she was working at the office.
Hilda looked after her new plants and sent Saffron pictures to show her progress.
Saffron replied with messages of encouragement which were cluttered with emoticons.
With Saffron’s guidance, Hilda left some plants to seed and harvested them. She returned a portion back to Saffron’s seed library and kept the rest for herself.
Hilda found therapy in her gardening. The care and love she put into it was meditative and it gave her a sense of peace. She realised how much more delicious her vegetables were than those that were sold at the grocery store.
Two years later, Hilda had a thriving vegetable patch. She started vertical gardening and sold strawberries at the local farmers market. Her strawberries were so popular that she started hosting workshops on growing strawberries in urban spaces. She no longer had to work in a boring and uncomfortable office for a stressful boss.
Hilda was happier
and felt like she was doing her part for the environment by recycling her kitchen scraps into compost and growing her own food.
If you would like to borrow some seeds, contact us. We would love to share them with you. We also welcome heirloom seed contributions too.
For more information about why we wrote this story, click here to read our previous blog about seed biodiversity and here about home food gardening. I recommend watching the movie SEED The Untold Story by Collective Eye Films.
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