Organic Gardening Techniques
Organic Gardening and Soil Health
Healthy soil = healthy plants = healthy people
To an organic gardener, soil is the most important aspect of the garden. The soil is a living entity, teeming with life, from earthworms, centipedes and beetles to fungi and bacteria. Healthy soil has minerals, nutrients, air and water to help plants grow. The more nutrients available in the soil, the more the plant can take up. The more nutrients in the plant - the more available for animals and humans. Therefore, human health is affected by the health of the soil in which our food is grown.
Organic farming protects and improves soil by restricting artificial chemicals (which can suppress the rich diversity of life in the soil) and adding bulky organic material such as compost, hay and manure to improve its structure. Wherever possible, soil should not be walked on, as a compacted soil is airless, difficult for roots to penetrate and a poor environment for soil structure.
Crop Rotation and Green Manure
Crop rotation is the practice of growing different types of crops in the same area in sequential seasons and is an important aspect of organic gardening. If one species were continually cropped in the same area, pathogens and pests that attack that particular family of plant would build up, so the changing of crops in a sequence tends to decrease the level of pests. Crop rotation also seeks to balance the fertility requirements of different crops to avoid excessive depletion of soil nutrients. A crop which depletes the soil of one type of nutrient should be followed by a crop that either returns the nutrient to the soil or draws a different ratio of nutrients. This reduces the need for artificial fertilisers which can be expensive and damage the local environment. Crop rotation can also improve soil structure and fertility by alternating deep-rooted and shallow rooted plants.
Planting a green manure crop is an important part of crop rotation. It usually involves planting a legume crop, such as beans or clover. Legumes have nodules in their roots which house nitrogen fixing bacteria. The bacteria fix nitrogen from the air into a different form of nitrogen which can be used by plants. In return, the bacteria are fed by sugars photosynthesised by the plants in their leaves. Other green manures such as rye has an extensive fine root system which improves heavy soil by opening up the structure. Green manures also smother weeds, protect soil from compaction by heavy rain and mop up plant foods from the soil so they are not washed away by rain.
Natural Pest Control
At Source we are attempting to control pests such as weeds and herbivores in the garden by natural means. Herbicides and pesticides damage soil organisisms and interfere with natural soil ecosystems. Chemicals can also harm beneficial insects as well as pests.
Our goal is not be free of pests and diseases, but to control them at an acceptable level. The best pest control techniques are preventative measures. Techniques include: crop rotation, maintaining healthy soil, garden cleanliness, plant choice, companion planting, encouraging natural predators and traps, barriers and deterrants. It is also important to realise that not all weeds are bad! Weeds can sometimes be edible, provide food and shelter for beneficial birds and insects, and useful additions to the compost heap. For example, dandelion greens can be eaten and contain as much iron as spinach. Stinging nettle can be brewed into a healthy tea or made into a delicious soup. Deep rooted weeds such as comfrey and dock can draw up nutrients from deeper in the soil profile and can be useful to add to your compost heap. Weeds can also be 'pioneers' of the garden, building up organic matter and preparing the soil for a community of plants to follow. Weeds can be indicators of soil health. For example, bracken can indicate a nitrogen deficiency and dock can indicate an acid soil.
Choose plant varieties for the garden that are best for local growing conditions and they will be healthier and more pest-resistant. If plants are allowed to self sow, these plants tend to be less susceptible to pests and diseases. Pulling out weak plants and disposing of them away from the garden area is also a good idea, as they can attract pests.
Building healthy soil with composting and mulching is the best way to promote strong, vigorous plants that can fend off pest attacks.
Crop Rotation and Mixed Plantings
Rotating crops is a good way to control pests as it prevents reinfestation of pests which have overwintered in the bed. Mixed plantings can slow the spread of pests throughout a crop.
Diversity: Encouraging Natural Predators and Companion Planting
Encouraging diversity in the garden is very important. For example, having ponds, rock heaps, bird boxes and refuge areas in the garden can provide habitat for predators such as birds and lizards that will dine on insects, snails and slugs.
Companion planting can include planting camouflage plants such as geraniums, mints, lemon balms and garlic in the garden. These fragrant plants mask the scent of the plant that needs protection, confusing the destructive insects. Some aromatic plants such as lavender, rosemary and marigolds can also repel insects. Sacrificial plants act as a decoy, and allow themselves to be smothered with pests, thus protecting neighbouring plants. For example, nasturtiums can atract aphids. They should be planted at a distance from the plants that need protecting so infestations do not spill over.
Trapping, Smothering, Barriers and Other Pest Control Methods:
At Source we have constructed a floppy-top fence as a barrier to possums invading the garden. The fence is also dug several feet into the ground so wallabies and other animals do not burrow underneath. There are some good pictures and text about building a floppy top fence at http://www.pindariherbfarm.com/selfsuff/flopfenc.htm
Mulching can be used to smother weeds for example a layer of cardboard has been placed underneath the woodchips, which will hopefully keep weeds down. Pigface has been planted on the steep banks as a living mulch to keep away other weeds, and also as a bank stabiliser. It also has beauitful pink flowers and edible fruit!
There are many other recipes, tips and hints for natural sprays, barriers and deterrants on the internet or in organic gardening books. For example, nails and slugs can be dettered by a variety of barriers such as wood ash, coffee grounds, finely crushed eggshells, hair or sawdust sprinkled around seedlings. They can also be attracted to and drown themselves in beer traps.
Composting is the decomposition of organic material by bacteria and fungi, recycling nutrients back the soil. Adding compost is one of the best things you can do for your garden as compost is both a rich soil fertiliser and adds humus to the soil, helping it hold moisture, structure and nutrients. Putting kitchen waste in the compost is far better than sending it to landfill. In landfill, organic waste can break down anaerobically, producing methane which is a potent greenhouse gas. Carting rubbish to waste disposal sites takes time, money and energy, and landfill space close to towns and cities is a declining resource.
There are many different technique of composting, including hot and cold, aerobic and anaerobic, above ground compost tumblers, and using composting worms. At Source there are 3 wooden bins on pavers. The pavers are to make the bins rat-proof, which was a concern of our neighbours, however it is often better to have a compost bin directly on the soil as it allows composting organisms such as worms and bacteria to move in more easily. Here the bins are filled one at a time and allowed to compost while the next bins are filled. By the time the 3rd bin is filled we hope that the 1st bin will have compost ready to put on the garden! Compost worms have been introduced to aid this process, which are different to normal garden worms. Any organic matter eaten by a worm is turned into rich humus and compost worms can eat up to their own weight in waste every 24 hours. They need protection from their natural predators; a warm temperature; adequate moisture; ventilation; the dark; and drainage. The bins are 1m2, which allows the centre of the bin to stay warm, helping the worms and other composting creatures to work.
Matter that can be put in a home compost bin includes: dry leaves, straw, dry grass, shredded paper, seaweed, sawdust, manure and fruit and vegetable scraps. Bascially, anything that was once alive can be composted, but it happens more quickly if small particles are used! Compost heaps should be moist but not wet and well drained. Air circulation helps to generate heat and speed up the process. At Source we achieve air circulation by using worms, but turning over the heap with a garden fork regularly works as well. Above ground tumblers can be rat proof and produce very quick compost. There are many different ways to make compost. Information can be found on the internet or in an organic gardening book find the one which suits you. Compost is ready to use when it has a crumbly texture and is brownish with a sweet earthy smell.
We hope to install a composting toilet at Source in the near future to recycle the nutrients from human waste and also reduce the amount of water used in flushing toilets.