The fifth Permaculture Design principle is ‘Using Biological Resources’.
This design principle is concerned with the use of biological resources to do work or conserve energy, rather than using non-renewable energy sources such as fossil fuel resources. Wherever we can use a plant or animal to perform a certain function in our designs, then this is our preferred approach.
For example, we can use livestock to keep grass short rather than use a lawnmower, or use plants that attract beneficial predatory insects to control pests rather than use toxic chemical pesticides.
It is critical to plan the use of biological resources early in the design process. You will need to figure which biological resources you wish to utilise on the site, and what your strategy will be to manage them. These biological resources will form the very basis of your energy recycling systems, and as a result, determine how sustainable your design will be.
To put it another way, biological resources are a key to recycling energy and materials, so the more you use them successfully, through a well planned strategy, the more sustainable your systems will be within your design.
It is important to point out at the beginning of this discussion, that even though we are looking to utilise natural resources in the place of less energy efficient non biological resources, we do not exclude the use of non biological resources if:
- They are used only at the beginning of a permaculture design implementation to help create lasting biological systems, or
- They are used only at the beginning of a permaculture design implementation to build long term physical infrastructure.
To provide an example of each, if our soil is so depleted that it cannot support any plant growth, we can responsibly use chemical fertilizer at the beginning to get our green manure plants growing, to commence the addition of organic matter and build soil fertility. The fertile soil will be a lasting biological system.
In the second case, we can use non-renewable fossil fuels to power earthmoving equipment, which we can use to build permanent physical infrastructure, such as dams and swales (contour trenches) for water harvesting and storage, and roads for access.
Practical Examples of the Use of Biological Resources
Listed below are various examples of using biological systems to create productive permaculture systems, while saving energy and resources – because we let nature do the work.
1. Using Biological Resources – Fertiliser
Conventional/unsustainable method – Chemical Fertilizer – is either mined (as in the case of potassium and phosphorus) or artificially synthesized using energy derived from fossil fuels (as is the case for synthetic nitrogen fertilizers). Both are unsustainable because mining of a finite resource is non-renewable, as is the fossil fuel consumed to manufacture synthetic nitrogen fertilizer.
- Chemical fertilizers are temporary solutions that do not improve soil quality
- Chemical fertilizers cause long term damage to the soil by killing the beneficial organisms that live in the soil and by making the soil to more acidic
- Chemical fertilizers cause long term damage to the soil by reacting with clay to create hard, dense layers of soil known as hardpan (which can be caused my natural and man-made phenomena),which restricts root growth and the movement of water, air and beneficial organisms through the soil, resulting in reduced plant growth, and as a consequence of trapping water, causing waterlogging and root rot.
- Synthetic nitrogen chemical fertilizers cause groundwater pollution and contamination – they break down into nitrates, or are already in nitrate form, which are highly water soluble, and are absorbed into the ground faster than the plants can absorb them, contaminating groundwater (where they can remain present for decades), polluting drinking water supplies and endangering public health.
- Synthetic nitrogen chemical fertilizers create runoff into waterways, creating massive “algal blooms.” The algae feeds on the nitrates, grows at a very fast rate, smothering the waterways. This algal bloom depletes the water of oxygen, suffocating fish and other aquatic life, creating huge “dead zones” in lakes and oceans. The number of identified dead zones in the oceans has been increasing in the last few decades. These dead zones not only affect the aquatic ecosystems in the area, but severely impact local communities who depend on these areas for food supply.
- Chemical fertilizers damage plant health – sudden large increase in nitrogen levels combined with a lack of trace elements have been known to cause diseases in plants.
Biological resource alternative:
In Nature, animals eat plant matter and produce manure, which provides nutrients to the plants. This is the fertilizer that plants evolved to utilise. Livestock can be kept to produces various resources, along with manure. Chickens and ducks produce eggs and meat, rabbits produce meat and they all produce manures which can be used to feed plants. On larger properties, greater numbers of livestock and/or larger livestock can be kept. On rural properties, goats and cattle can be used to supply milk, and sheep can be kept for wool production, and these larger animals provide greater quantities of manure. Horses can be kept for recreation, transportation and will also provide manure. This ties in with the second Permaculture Design principle – ‘Each Element Performs Many Functions’.
Nitrogen Fixing Plants
Plants can also be used to add fertility to the soil. Nitrogen fixing plants have root nodules which contain the symbiotic Rhizobium nitrogen fixing bacteria, which can take nitrogen from the air and convert it to a form usable by plants. This nitrogen fixing process in the root nodules helps the plant to grow, and when the plants drop their leaves, or when the roots die back (because the foliage is pruned), usable nitrogen is returned to the soil. Nitrogen fixing annual plants can also be grown as green manures, then cut down as soon as they begin to flower so they release all their nitrogen into the soil. If they are not cut down, the nitrogen goes into their beans, peas, etc.
The most common nitrogen fixing plants are the plants and trees from the family Fabaceae (bean and pea), which includes legumes such as alfalfa, beans, clovers, lupines, peanuts, peas, and leguminous trees, such as tagasaste (tree lucerne) and acacias.
Note, there are some members of the Fabaceae family which do no fix nitrogen, such as carob and honey locust trees.
Conversely, some non-leguminous species have the ability to fix nitrogen, such as alder, bayberry, casuarina, eleagnus as well as the tiny floating aquatic fern azolla (fairy moss).
Dynamic accumulators are plants that have tap-roots which drill down into the deeper levels of the soil and ‘mine’ certain nutrients, which they accumulate within themselves. When these plants die down, the accumulated nutrients are release to the surface of the soil where they then become available to other plants.
Some common dynamic accumulator plants include comfrey, stinging nettle, borage, clover, dandelions, strawberries. lemon balm and yarrow.
Comfrey has nitrogen rich leaves, and can be used as a compost activator (as can yarrow). Comfrey leaves can be composted or fermented to produce a nutrient rich natural fertilizer.
Green manures are crops grown to supply organic matter and improve the soil. They are not harvested, but are cut down to form a mulch on the soil surface or dug into the soil just as the flowers start to form.
Green manures have many benefits, they can:
- Provide ground cover which prevents soil erosion and stop weeds growing
- As dynamic accumulators, bring minerals from deep within the soil to the surface, and break up compacted soil and hardpans
- As nitrogen-fixing plants, Increase the soil’s available nitrogen
- As a mulch, increase organic matter, and as a consequence, increase beneficial micro-organisms, earthworms and the moisture retention capacity in the soil
- Providing habitat, and a food source of nectar and pollen for beneficial insects, which reduce the number of pests in the garden
- Through the action of their roots, as well as from their roots decomposing after they have been cut down, create intricate and extensive channels in the soil which Improve water and air penetration in the soil, and assist other plant roots to penetrate into the soil.
Plants which are used as green manures include:
- Cool season green manure crops, such as Broad Beans, Fenugreek, Linseed, Lupins, Mustard, Oats, Rapeseed, Subterranean Clover, Vetch
- Warm season green manure crops, such as Buckwheat, Cowpea, Japanese Millet, Mung Beans, Mustard, Soybeans
2. Using Biological Resources – Pest Control
Conventional/unsustainable method – Chemical Pesticides– highly toxic synthetic poisons derived from petrochemicals/fossil fuels.
- Chemical pesticides kill soil organisms, destroying soil biodiversity, and reducing soil quality and are persistent in soil for very long periods.
- Chemical pesticides pollute water sources by entering the water through the air during spraying, or by runoff or percolation to groundwater. Once in the water, they can poison aquatic ecosystems, disrupt ecological food chains, and damage human health.
(In a study by the US Geological Survey in the United States between 1992–2001, pesticides were found to pollute every stream and over 90% of wells sampled.).
- Certain pesticides which are also classed as “oestrogenic compounds” because they disrupt the endocrine system of animals by mimicking natural hormones, also disrupt the nitrogen fixing process in legumes, and can reduce nitrogen fixation by as much as 90%.
- Chemical pesticides can kill bees and other beneficial pollinators, resulting in a loss of pollinator colonies, and a consequence, a reduction in seed and fruit production in plant species that depend on these pollinators.
- Use of chemical pesticides creates a process of natural selection where pests evolve to become resistant to pesticides.
- Pesticides kill beneficial predator insects which eat the pests, resulting in greater numbers of pests after the use of pesticides.
- Pesticides has harmful effects on plants, affecting plant growth and development
- Sprayed pesticides only partially reach the intended target area, the rest drifts off elsewhere. Of the sprayed pesticide that actually reaches the target area, only about 2% of the pesticide applied actually hits the target pests.
Biological resource alternative:
Beneficial Predators – Insects
Rather than trying to control pests, we can create an environment that attracts predators of pests, which will eliminate the pests for us naturally.
Beneficial predatory insects can be attracted to the garden by planting plants that provide them with:
- an alternative food sources such as pollen/nectar source
- a habitat or shelter in which they can live, lay their eggs or survive the overwintering period
The main plants that appear to attract and and provide a rich nectar and pollen source for beneficial insects belong to the Umbelliferae (parsley) and Compositae (daisy) families.
The Apiaceae (formerly Umbelliferae) family are characterised by umbrella-shaped clusters of small 5-petalled flowers, which form a large flat head of white or yellow flowers. Plants from this family include angelica, anise, carrots, caraway, celery, coriander, cumin, dill, fennel. lovage, parsley, parsnip and Queen Anne’s Lace.
The Asteraceae (formerly Compositae ) family are characterised by disk-like flower heads made up of “composites” of many tiny flowers growing together, arranged like rays around a centre. Plants from this family include asters, calendula, cosmos, dandelions, daisies, sunflowers, tansy, yarrow and zinnia.
The most popular ones are any type of mustard plant, as well as other early blooming nectar and pollen sources, like buckwheat, coriander, red clover, and legumes like vetches
These plants flower over a long period of time, and provide a steady and abundant flow of nectar and pollen for the beneficial predatory insects, which extends their lifespan, and allows them to lay more eggs, and consume more pests.
In addition to these families of plants, beneficial predatory insects need a permanent shelter, so it is important to have perennial plants in the garden to give them a home all year round and to provide over-wintering locations. Include ground cover plants, low herbaceous plants and shrubs create a good habitat.
The beneficial predatory insects attracted by these plants include Ladybirds, Lacewings, Hover flies, Parasitic wasps.
Other beneficial insects which also consume garden pests are Dragonflies, Praying Mantis and Spiders
Beneficial Predators – Other
There are many other species that consume garden pests :
- Lizards eat many garden pests, and can be drawn into the garden if you create a suitable habitat for them.Lizards require debris that provides shelter and refuge from predators through camouflage. Leave a good supply of leaves and twigs on the ground – this provides habitat for the insects the lizards use as a food source and also enable the lizards to move around safely. Leaving natural mulch on the ground will also attract microorganisms that improve soil condition, act as a weed control, and help with saving water. Hollow logs, crevices between bricks and rocks, groundcover plants and native grasses offer protection too, as well as a place to hibernate during the winter months. Lizards are cold-blooded and therefore rely on the sun to raise their body temperature. Incorporate flat, dark-coloured rocks into your garden landscape where they can be warmed by the sun, and make sure some shelter is near, so that sunning lizards can retreat if in danger. Elevate the rocks slightly, or put them in a little pile so the lizard can slip under it if threatened. A log or brick path will also absorb the warmth of the sun. Plant groundcovers near the edges to provide extra cover.(Source: Creating a Home for Lizards, Backyards for Wildlife Fact Sheet – Urban Biodiversity Unit, Department of Environment and Natural Resources, Government of South Australia)
- Frogs are another insect-eating species, and being amphibians which live in an aquatic environment, can be attracted into a garden by constructing a pond.
When creating a habitat for frogs make sure you provide lots of plants, especially natives, plenty of ground cover, rocks, logs, leaf litter and moisture. A frog pond will provide water for frogs to breed, find food and stay moist. Frog ponds do not have to be elaborate to be successful. In terms of placement the pond should be part sunny, part shady, but not directly under trees, look for a low point in your yard where water naturally collects. The design of the frog pond should have shallow edges and a flat base, be at least 50 cm in depth in one spot. It should have rocks, logs and plants in and around the pond edges, plants and logs in the pond and the base covered with washed sand or gravel. A circulating pump with make the water less appealing for mosquitoes, and water lilies help discourage algal blooms.(Source: Creating Frog Habitat – Frogs Australia Network)
- Birds are another means of pest control. You can attract insectivorous birds by building nesting boxes for them, or by growing thorny shrubs, in which they can nest safely and be protected from predators. Insectivorous birds are attracted to the same plants and trees as nectar feeding birds, so it is helpful to plants a variety of bird-attracting trees and shrubs so there is something flowering all throughout the year. This will ensure that you will have birds constantly present all year round.Birds need water to drink or bathe in, but birds like the water elevated so they feel safe. Locate the water near trees or shrubs, especially thorny shrubs, to give them privacy and protection.
3. Using Biological Resources – Erosion Control
Plants can be used to stabilise exposed soil to prevent erosion. In fact Nature does this automatically with pioneer plants (often erroneously called “weeds”). These plants will cover any bare patch of soil to stabilise it, and commence the first step in ecological forest succession which will ultimately turn the area (if possible) into a stable climax forest.
We can use various plants and trees for erosion control:
- Ground cover plants will cover and protect the soil, preventing the wind and rain from removing the topsoil, while sheltering it from the sun to reduce water evaporation and loss of organic matter.
- Where hillsides have been deforested and are being eroded by flowing water, reforesting the area will prevent erosion.
- In warmer climates, Vetiver grass, which has a strong dense network of roots that grow vertically downward to a depth of two to four metres, binds the soil together and is used to stabilize steep slopes, stream banks and terraced hillsides. The grass grows up to 1.5 metres high, which serves as an effective barrier to soil surface erosion.
- Willows are used in extensively in soil bioengineering for stream bank stabilisation and restoration. Willows quickly produce a very dense mat of roots which will stabilise the banks of any watercourses, and since they are not affected by having their roots submerged, they scan stabilise the soil all the way to the water’s edge. Once the banks are stabilised, a whole living thriving ecosystem can develop around the shelter and microclimate created by the willow.
4. Using Biological Resources – Fire Control
A fire barrier can be constructed using fire retardant and resistant plants and trees – a shelter belt, which is a wide strip of deciduous fire resistant trees and plants that can shield the house from radiant heat, and catch wind blown burning embers.
Trees suitable for this purpose are typically European deciduous trees, such as deciduous fruit and shade trees.
A selection of suitable trees includes:
- Deciduous fruit trees in general
- Poplars, aspens, and cottonwoods
- Mirror bush (Coprosma repens)
A shelter belt can be planted at the boundary of the 30m perimeter between the house and the surrounding forest or wilderness.
(Note: An extensive list of fire retardant/resistant plants and trees can be found in the Permaculture Principles article 3. Each Important Function is Supported by Many Elements)
5. Using Biological Resources – Tillage
Tillage is the term used to describe the agricultural preparation of the soil by digging it and turning it over.
The soil is a very complex ecosystem, filled with a diverse range of soil life that is critical for plant growth and health. Digging and turning over the soil exposes a very delicate ecosystem to the air which dries it out, and to the ultraviolet rays of the sun, which sterilize the soil – killing the soil organisms. The soil loses a lot of its nutrients, such as carbon and nitrogen It also loses a lot of its organic matter, and as a consequence, does not retain water as well. The delicate soil structure is destroyed, compaction of soil occurs, leading to hardpan formation, and reduced water infiltration in the soil, and more surface runoff, which increases soil erosion.
Biological resource alternative:
In Nature, soil does not to be manually cultivated for spectacular forests to grow. What holds true in Nature also holds true in the garden. In a forest, organic matter in the form of fallen leaves, twigs and braches, annual plants at the end of their yearly cycle and other plants at the end of their lives are all deposited on the forest floor when they decompose into rich humus.
We can add organic matter directly to the soil surface, such as manure, compost, straw, leaves etc. Garden waste such as prunings from trees and shrubs can be fed into a mulcher to be broken down into small pieces, and then spread over the soil as a mulch. Adding a layer of organic matter over the soil, in a layer approximately 5cm-15cm (2”-6”) thick is in effect ‘sheet composting’, where the garden beds become large composting areas. By the action of earthworms, bacteria, fungi and insects, the organic matter is slowly broken down and released into the soil, providing nutrients to the garden. Because the soil is not disturbed, a stable soil ecosystem is created, and plant health is improved. Moisture is also better retained due to the mulching, and the organic matter in the soil works like a sponge to better retain the moisture in the soil. The mulching also prevents soil erosion, stops runoff of rainwater across the surface, and assists the rainwater to percolate into the soil. The earthworms will create channels in the soil, which will help both water and air to penetrate into the soil.
With no-dig gardens, the soil is not compacted because it is not walked upon. Stepping on the soil destroys the soils structure by compacting it, preventing air and water penetration to the plants roots, which affects plant health, restricts plant growth and reduces productivity.
Chop and Drop
In Nature, when plants die down, they stay in the same place. They’re not uprooted and disposed of! Do not uproot annuals that have finished producing at the end of the season, cut the stem at soil level. The roots will rot away to create thousands of intricate air and water channels in the soil that you could never manually replicate. The tops of the chopped down plants can either be laid down whole, or chopped into smaller pieces to speed up their breakdown, to create a natural sheet compost system like the forest floor
In permaculture, we always use the best and most (energy) efficient resource for each task. In the same way that we can use earthworms to do our digging, because earthworms dig much better than we do, we can also use animals to weed, fertilise and clean up the garden. An animal tractor is a movable enclosure in which animals are placed so that they can scratch, dig, eat weeds,and manure the soil. The enclosure ids left in an area long enough for the animals to do their work, and then moved to a new area. It is not left permanently in one area because excessive soil disturbance will result.
Many animals can be used in animal tractors. The most common are chicken because they scratch, dig, eat weeds and pest insects, and manure the ground very well. Other suitable animals are rabbits, guinea pigs, ducks, geese, turkeys,pigs and goats.
These are just some of the possible practical examples of where biological resources can be used in place of non-renewable energy sources to do work in a Permaculture system, the possibilities are almost endless. Considering that Nature grow all plant life quite well without human assistance or intervention, by looking at how Nature achieves this, we can recreate the same energy efficient systems in our Permaculture designs.
The examples not only show how using biological systems is a more energy efficient practice than using non-renewables such as fossil fuels, but how the use of these non-renewables actively cause extensive damage to ecosystems of which we are a part, ultimately causing harm to ourselves and all other species. So, it is quite evident that using biological resources in our designs not only save energy, but save the planet!
2nd time caller, your website/garden/results are awesome.
Your mandarin tree seems to love the conditions and the comfrey.
I am looking to add a few extra Comfrey plants to my back yard orchard as it is very recommended by everyone else but seem to recall that you limit the Nitrogen(?) to your trees to help keep them smaller. You don’t seemed to have added additional comfrey plants to other areas but would you recommend it below fruit trees… or is it too good(!!) as a companion plant for back yard orchards??
Thanks and live your work!!
Hi Steve, citrus trees are heavy feeders and have higher nitrogen requirements than deciduous fruit trees. My regular fruit trees only get a feed of manure or some other natural nitrogen source at the start of spring and autumn. I’m careful not to overfeed the garden with nitrogen, that’s as bad as underfeeding, and the soft, sappy growth that results from excessive nitrogen levels encourages sap feeding pests such as aphids and scale on most plants..
Makes total sense, you are a legend at making the complicated easy to understand.
So no go for the deciduous but good for citrus… would the other evergreen trees I have being olives, tamarillo, feijoa, babaco and avocado, would they benefit from a plant underneath?
Thanks Steve! Using comfrey near deciduous trees is fine and won’t add too much nitrogen at all. I just use it under one of my citrus trees because citrus need the extra feed, and it meshes nicely with the citrus fruiting season, the high potash content in the comfrey leaves is released back into the soil when it dies down in winter, the time when citrus fruit is around, and potash is necessary for fruit and flower production!
My food forest garden is really a high density design, if I used comfrey under all of my trees, I wouldn’t have space to grow anything else or put in any other companion plants! : )
Do you have experiences/knowledge of forest gardens containing trees, shrubs and perennials, interplanted with annual vegetable crops WITHOUT the use of manure at the start of the system? I use all the green waste we have in the garden (cuttings from carpinus betulus hedges, vegetable wastes, grass mowings and so on), to build a healthier soil, but I wonder if it will take me a lot of time before annual vegetables grow well there. I plant N-fixating and mineral accumulating plants too, and next to the garden is a potato field which gets lots of fertiliser (and pesticides) from the farmer, which makes the ground/soil water and the air N rich. I haven’t added minerals (lava grindings or algae). Yet.
Manure isn’t the only source of nitrogen, there’s a long list of nitrogen containing materials in my hot composting article – http://deepgreenpermaculture.com/diy-instructions/hot-compost-composting-in-18-days/
Often manure is used to accelerate the process of getting a lot of nitrogen in the soil quickly, and if you don’t grow annuals that are heavy feeders the first year, you get an extra year of soil building activity, then you can grow heavy feeder annuals afterwards.
You’ll have plenty of water soluble nitrogen fertilizer run-off coming in from the farm next door if you’re downhill of your neighbours, otherwise groundwater contamination of fertiliser and pesticide wont make too much of a difference to shallow rooted annual. Don’t worry about the air, it’s always around 78% nitrogen everywhere, nitrogen fixing plants don’t ever have a shortage of nitrogen anywhere on the planet!