A website worth reading.
The Ecological Agriculture Australia Association (the EAAA) adds a new dimension to agricultural education, extension, research, and, politics.
The organisation stands between the world of industrial agriculture on the one hand, (which we have little affiliation with), and organic agriculture on the other, (which we do have affiliation with).
In essence EAAA is driven by an ecological imperative. We believe that ecology is the foundation stone of agriculture and that this science (which embraces its natural and social elements) needs to be the primary driver of all management decisions.
The EAAA’s mantra is one of looking after that which we are dependant on – in this case the biosphere.
“To build a sustainable society, we must first be willing to rethink our fundamental concepts of science economics, and society. We must build a new sustainable society on the philosophical foundation of a new worldview, a new approach to science, a new economics of sustainability”~ John Ikerd
This is an excellent article that explains the decay process of wood chips and how to combine them with nitrogen sources so you can use them as soil builders without pulling nutrients from your existing soil.
Building Garden Soil With Wood Mulch
In the short term (two years), wood mulch can potentially lower soil fertility, but in the long term their value in building garden soil is beyond question.
By Barbara Pleasant
SOURCE : http://www.motherearthnews.com
Most organic gardeners find that following nature’s patterns serves them well. When it comes to building richer soil, nature’s plan relies heavily on trees — fallen limbs, leaves, cones, seeds and, eventually, the massive trunks. Adapting this plan for building garden soil by using a wood mulch — such as wood chips, sawdust or other woody residues — is a strategy that promises huge, long-term returns.
Field studies dating back to the 1950s — and as recent as this year — suggest that a high-fiber diet of woody materials is exactly what many soils need. Rotted bits of wood persist as organic matter for a long time, enhancing the soil’s ability to retain nutrients and moisture, which results in bigger, better crops.
But wait: Woody materials are high in carbon and cellulose, so they need nitrogen and time in order to decompose. If you ignore these facts by mixing fresh sawdust or wood chips directly into your soil, the materials will bind up much of the soil’s nitrogen and render the spot useless for gardening for a season or two.
The outcome changes, however, if you add nitrogen or time. For example, when researchers planted a new organic apple orchard in northern Maine in 2005, fresh wood chips combined with blood meal (a very high-nitrogen organic material with a typical analysis of 12-0-0) and tilled into the top layer of the soil — plus a surface mulch of wood chips — proved better than three other treatments at promoting rapid tree growth. And, in less than two years, the organic matter content in the chip-amended plots went from near zero to 2 to 3 percent.
Sawdust has much more exposed surface area than wood chips do, so incorporating fresh sawdust into soil is not a good idea chemically (because of nitrogen tie-up) or physically (the mixture won’t hold water worth a flip). But sawdust makes a spectacular mulch for perennial crops. As long as you scatter a bit of organic fertilizer, poultry manure, or other nitrogen source over the surface each time you throw on a fresh layer, sawdust makes unsurpassed mulch for blueberries, strawberries, and raspberries, and it can work well with asparagus, too.
Garden paths paved with sawdust-covered newspapers feel like carpet underfoot. After it has rotted, sawdust contributes mightily to soil’s texture, because the spongy tidbits persist in the soil for a long time. The concern that woody amendments acidify soil is a myth. Only in the early stages of decomposition is there a fast flush of acids, when cellulose fibers begin to degrade. Long-term studies of the effects of wood chips and sawdust in soil actually show a slight rise in soil pH, which is good news for most crops in most gardens. (The lower the pH, the more acidic the soil.)
In the Maine apple orchard study, the research team observed that the wood chip plots became covered with white mycelium, which is the vegetative form of many fruiting fungi and is commonly known as white rot. The development of these fungi in the wood mulch increases the amount and enhances the character of organic matter in the soil, as well as helps the soil’s ability to retain moisture. The huge group of fungi known collectively as Basidiomycetes is a core player in wood chip decomposition. Many produce mushrooms — pretty, but not generally edible. Where moist wood chips and soil unite, these fungi use enzymes to access nutrients in the wood, which is their energy source for the growth of threadlike, white hyphae. The hyphae knit themselves together into mycelium, which is easy to see. In addition to fungi, several specialized types of bacteria are able to degrade high-cellulose materials such as wood chips, while others digest failing fungi. Seen this way, it’s easy to envision wood chips in soil as life rafts that support three major levels of soil life: the fibrous organic matter of the chips themselves, the biological mass of filamentous fungi that grows on them, and beneficial bacteria that come and go in waves.
Starter colonies of these microorganisms are usually present on the bark of chipped branches. Tradd Cotter, mycologist and owner of Mushroom Mountain in South Carolina, says fungi present on wood start growing quickly after wood has been cut or chipped. In moist climates, there may be no need to add a fungal inoculant to kick-start the process, but Cotter says providing inoculants in the form of sawdust spawn (sawdust covered with actively growing mycelium) can speed and enhance the soil creation process. Maybe you’ll get some edible mushrooms in the process, too. “The native edible species king stropharia (Stropharia rugoso-annulata) is by far our best wood-decomposing strain,” Cotter says. “It is spreading through our gardens, increasing soil depth, and attracting beneficials, such as earthworms.” Sawdust or wood chip spawn ofstropharia (winecaps) and other species are available from Mushroom Mountain, Field and Forest Products and Fungi Perfecti.
Wood chips and sawdust are each byproducts of other activities, so finding good-quality, local resources is your first step. If you live near a sawmill, you can probably get sawdust cheap, though you’ll need assurance from the sawmill operator that it doesn’t include black walnut sawdust, which releases a toxin that can be murder on tomatoes and other sensitive vegetables. Also avoid sawdust from plywood and painted or treated wood in your garden because of the glues and other chemicals. With sawdust, the lower you go on the production chain (a sawmill that handles whole logs), the more likely you are to get garden-worthy sawdust. For soil-building purposes, coarse sawdust is better than fine because it’s less likely to pack into a mat, and it lasts longer as organic matter in the soil.
If kept moist, sawdust can decompose surprisingly quickly. In a study at Ohio State University, sawdust rotted faster than newspaper or straw, both of which were still recognizable after 16 weeks. To speed up rotting in a pile of sawdust, simply add moisture and nitrogen. This can be done by mixing up a big batch of fish emulsion, pouring it into an already damp, doughnut-shaped sawdust pile, and then covering it with a tarp or an old blanket to retain moisture. After sawdust turns black, you can use it to lighten up any soil — including potting soil — for seedlings and container gardening.
Most of the more recent studies with wood chips used what are called ramial wood chips, which are what you get when you put live, leafless hardwood branches, 2 to 3 inches in diameter, through a chipper to create pieces that are a half to 1 inch wide and 1 to 4 inches long. Ramial chips have relatively little bark and heartwood because of the size of the branches used, which is part of what makes them so attractive as a soil amendment. Superior batches also contain few leaves, cones, or other prickly parts.
You can get ramial wood chips for free by connecting with tree-trimming crews working in your area. In some towns, such as Oshkosh, Wis., you can take small limbs to a chipping center on certain Saturdays and go home with your own homegrown wood chips. Wherever you live, a few phone calls to local utility companies or tree service companies should be all it takes to find a free supply. Wood chips often end up in landfills; let’s put them to use enriching our garden soils instead.
This is a good guide if you are thinking about using goats to manage weeds or to help regenerate bush land.
source – http://www.acga.org.au/goatnotes/J001.php
Using portable electric net fencing works very well when wanting to isolate grazing areas.
Weed Control Using Goats
- Peter Holst, NSW Dept. of Agriculture, Cowra, NSW
- Helen Simmonds, “Rowan Park”, NSW
Weeds in pasture greatly reduce the short and long term profitability of the pasture. The traditional methods of weed control in pastures are cultural, biological, chemical, mechanical or grazing. Not all are necessarily effective or desirable.
Preferential selection (palatability) of plants by animals is affected by plant and animal based factors.
Animal-based factors may be categorised into five classes:
- the senses
- species and breeds
- individual variation
- previous experience
- physiological condition
The actual ability of goats to utilise a variety of vegetation types is attributed to their dexterity, narrower mouth, mobile upper lip, prehensile tongue and a propensity to stretch upward on the hind legs to reach forage.
Plant-based factors include:
- intra specific variation
- chemical composition
- morphology or physical traits
- succulence or maturation
All animals have dietary preferences. This can be observed in horse paddocks, or on adjacent sheep or cattle properties, where the weed problems are different to where goats are run. Goats eat a variety of undesirable plants and shrubs that sheep and cattle avoid, and often the nutritive value of these species is quite high.
Goats are efficient browsers and grazers of uncontrolled plants in rocky outcrops. They will also eat any weeds that germinated too early or too late to be affected by herbicides. Similarly, degraded non-arable country with woody and other weeds may be reclaimed by goat grazing.
The major control process is ecological, as the weed is placed at a comparative disadvantage in the presence of vigorous clover. This is because clover is not highly sought by goats.
In Australia we have both fibre and meat type goats that are suitable for weed control. In general the bush goat (derived from ferals), cashmeres (not off-shears), and boer X goats can be used.
The principle roll of the goat as a weed controller is to place the weed at a competitive disadvantage to the surrounding pasture. They preferentially graze the weed, preventing it from flowering and setting seed, reduce the plants stored energy reserves, and finally, ringbark and trample small bushes.
Advantages of using goats include the savings in the cost of chemicals, time, labour and machinery, also a sustained and efficient level of control. The returns from the “spin-off” profits make utilising goats plain common sense.
Assessing Pasture and Weeds
Before you can devise a stocking strategy you need to assess pasture quality and quantity and the degree of weed infestation. This is best judged in the weed”s late vegetative stage, before flowering. Simply estimate the percentage ground cover of the weed in a square (0.5m x 0.5m). Walk over the entire paddock and repeat the assessment in about 30 random positions.
For larger woody weeds (blackberry, broom, gorse) estimate the proportion of the paddock taken up by the weed.
From these assessments, and with the knowledge of weed palatability (see Table 1), you can devise a stocking strategy.
Any necessary improvements must be made before goats arrive on a property. These include fences, water points, and yards.
Goats test the lower portion of fences: any drains, low areas and diagonal stays etc. will need to be attended to, to ensure there are no escapees. Electric fencing is a reliable and inexpensive method of upgrading existing fences. As a general rule, any fence that will contain crossbred ewes will contain goats.
For localised woody weed infestations, it may be best to isolate the infestation with fencing. This has two benefits. It confines your goats to the infested area, so that fewer goats may be required for the job of controlling the weed; and it preserves the remaining pasture for your sheep or cattle.
In dense infestations of woody weeds such as blackberry, scotch broom or gorse, slash paths through the infestation to allow greater access for goats.
Goats will ringbark some mature trees, particularly over the late winter/spring period. Soft-barked gums are most at risk and so may require protection from goats. You may need to take protective action if your goats begin to chew the tree bark. Even within the same species, individual trees will have a different attractiveness to goats. A trace element salt lick is always useful and often negates the need to attack trees.
Wire mesh wrapped twice around the trunk to a height of 2 metres will prevent damage. Exposed roots may also need covering.
Control or Eradicate
Control is achieved by stopping the annual replenishment of seed reserves in the soil, and eradication is achieved after the exhaustion or effective suppression of these seed reserves. Therefore, eradication of a weed depends on several years of continuous control.
Efficient control is achieved by goat grazing, even though the goats are consuming seedheads of weeds. Research has shown that very few of the seeds ingested by goats remain viable.
“Set” or “Strategic” Stocking?
Knowing how palatability varies at each stage of plant growth allows you the flexibility of either set stocking or strategic stocking.
Set stocking with goats can be an advantage in the first year of a weed control program. It allows you to “quarantine” the new animals, a good management strategy in case the animals are affected by lice or other health problems. It also reduces the cost of upgrading fences, as only one paddock will require upgrading.
However, after the quarantine period, it is advisable to integrate other livestock. This ensures peak production from the herbage in the paddock.
The strategic grazing option requires goats to graze alongside other stock at the “strategic” time – for example when the weeds are most palatable to the goats (as when thistles are flowering) so that competition with other livestock for feed is greatly reduced. Because strategic grazing, by definition, is only used at particular times there must be alternate grazing and holding areas for the goats. This means you will have to fence both the weedy paddock and the other holding paddocks.
The integration of goats on a farm can be ecologically and economically significant. These comments on management are intended to be positive and allow sound management of the animals. The few hours per month involved in sound management are negligible to that involved in traditional weed control.
Table 1. The potential toxicity, and palatability, of some Australian plants to goats.
|Flower||= Eaten at flowering|
|High||= High palatability|
|Low||= Low palatability|
|Medium||= Moderate palatability|
|Nil||= Not eaten|
|Physical||= Physical damage caused by goats|
|Recent||= Recent growth, regrowth|
Grazing impact is a result of plant selection (palatability or aversion) rather than plant availability so that Table 1 directly assists grazing management while the genera listing helps our understanding of palatability, toxicity, and the theory of aversion (Provenza, 1996).
These are indications of potential toxicity only, and not all of these are applicable to goats,who have a remarkable digestive system. Many plants are found as garden refuse, and fed to livestock as a “treat”, while others are found naturally in grazing areas.
For further information see: “The Potential Palatability and Toxicity of Australian Weeds to Goats”. Simmonds, Holst and Bourke. This also includes new information on palatability to goats of many more weeds.
© 2000 ACGA
IT’S TIME TO BURY THE HORNS!!
Biodynamic Agriculture is looking for volunteers who would like to come and join us for this wonderful event, learning about biodynamic farming and gardening methods, while burying our Autumn horns to make the preparation BD500.
If you are interested in learning about biodynamics, digging and getting dirty, this practical hands on experience of helping to make preparations, is a great experience!
Come on down to 25 Nobles Lane, Bellingen any Monday – Thursday (5th May – 15th May).
We start at 9am and finish each day at 3.30pm – You can stay for an hour or stay all day!
We welcome members and friends of BAA, WOOFERS, farming and gardening enthusiasts, and anyone with an interest in biodynamics.
It’s FREE to participate and Morning Tea is provided daily.
Call the office 02 6655 0566 for more details
Due to high moisture evaporation rate in the high altitude region of New England I have come to observe low levels of soil life. What is equally concerning is the potential lack of microbial activity.
While researching methods to increase microbial life in soils I came across these short but succinct articles one from http://www.reap-canada.com the other from modernfarmer.com
As suggested the application of straw can encourage microbe activity. Experience has taught me thus far that to slow the rate of evaporation we must be applying much more organic matter – like straw – to help build soil and limit moisture loss, to gardens and pasture.
“Though researchers continue to develop promising new microbial cocktails, there is an increased focus on guiding farmers to better steward the populations that already exist in their soil. Kinkel is working on an approach she believes will help farmers sustain optimal microbial communities by ensuring they have the food they need — carbon — at all times. She calls it ‘slow release carbon’, but it’s not something farmers will see in supply catalogs anytime soon.”
Article posted with permission from Green Harvest
Green Harvest is a family owned and operated Australian mail order business that has been trading since 1992. It started out simply from a desire to share their passion for organic gardening and permaculture.
They were the first organically certified seed supplier with BFA – ACO in Australia. Their website is the most comprehensive source in Australia (and possibly the world) of both organic gardening products and information on organic growing.
Green Harvest aim to make it easier for Australians to live in healthy, natural homes with a garden full of nutritious, chemical-free vegetables and fruit.
Improving Your Soil Organically by Frances Michaels ©
Healthy soils are a complex web of life, teeming with earthworms, beneficial fungi and bacteria. They smell good and are moist and crumbly. Roots are able to penetrate easily, deep into the soil. Plants growing in healthy soils have fewer pest and disease problems. If your soil doesn’t match this picture of health but instead dries out to a cement-like texture, is devoid of life, with plants that look sickly and are plagued with pest problems, then your soil is in desperate need of organic matter. Using the following suggested strategies will build organic matter levels and so improve the soil health.
So what is organic matter? Simply anything that was once living: weeds, manure, hair, paper, kitchen scraps. Organic matter brings life to the soil, by providing food and habitat for beneficial microorganisms. As organic matter decomposes, through the activity of soil organisms, nutrients are made available to growing plants. Organic matter improves soil structure, allowing the free passage of air and water, both equally necessary to the growth of plants. It acts like a sponge, holding onto water and nutrients. Soils high in organic matter are like those you would find in an undisturbed moist, mountain forest and can actually feel spongy to walk on.
Australian soils are often very low in organic matter and nutrients; this is fine for a garden of native plants but needs to change if you want to grow fruit and vegetables that have evolved under very different soil conditions. There are many different ways of adding this all-important organic matter to our soils, from the recycling of food scraps and weeds, commonly known as composting, to the growing of crops specifically for organic matter production, referred to as green manuring. To protect our soils from erosion and summer heat we need to mulch them. This provides organic matter as it decomposes and also creates habitat for insect predators.
Understanding a Carbon to Nitrogen ratio (C : N) ratio will allow you to build successful compost heaps and use mulch materials correctly. All organic materials such as manure, weeds, grass clippings and kitchen scraps have a C:N ratio. The higher a material is in nitrogen the faster it will decompose, the higher it is in carbon the slower it will decompose. The mix of materials in a compost heap needs a ratio of approx. 25 carbon to 1 nitrogen to break down successfully. If the compost heap is too high in carbon it will not heat up, so you will need to add a source of nitrogen such as blood and bone, chicken manure or urine. If it is too high in nitrogen, it will get hot very quickly but nutrients will be lost as nitrogen converts to its gaseous form, ammonia. A general rule for compost heaps is ‘if you can smell it, you are losing it’. Add more carbon to prevent this such as straw, small amounts of sawdust or wet, shredded newspaper.
All organic materials will eventually rot, regardless of what you do. Composting is the art of producing rich, sweet smelling decomposed product rather than a wet, smelly, fly attracting, rotting mess. There are two main ways to go, using a bin or tumbler or building a compost heap. An enclosed bin is very useful for people with small backyards and has the advantage of being rat-proof. Management is necessary to get the right mix of carbon to nitrogen in bins. Kitchen scraps alone are generally too wet and too high in nitrogen. As each bucket is added a small amount of drier, high carbon material such as shredded newspaper or sawdust should be mixed in. Good compost will contain a range of ingredients, the wider the range, the more likely that a full range of nutrients will be included in the finished compost. Suitable ingredients include: cow, horse and poultry manure, comfrey and arrowroot leaves, legumes, wood ash, grass clippings, weeds (avoid adding weeds that have gone to seed), seaweed, kitchen scraps, leaves, hair, sawdust (small amounts only), feathers, soaked newspaper, animal bedding, fish waste and crop residues.
The completed compost heap should be as moist as a squeezed out sponge. If the heap is too dry, white threadlike strands will appear and fungi will become the main decomposers rather than bacteria. It should be covered to keep out rain, as it will become anaerobic if it gets wet and soggy. Place it in the garden to take advantage of any nutrient rich run-off, such as close to a citrus tree. Turning the heap speeds up the process and gives a more even result. A minimum size of about a cubic metre is needed for a heap to reach a sufficient temperature to kill weed seeds.
Never try to kill pests such as fruit fly in your compost heap as they are able to move away from the heat and complete their lifecycle. Avoid adding lime to compost heaps as this will increase the loss of nitrogen from the heap. Incorrectly stored animal manures can lose 50% of their nitrogen during storage. Always store manure undercover, using a tarp or old carpet to protect from rain and sun. If a compost heap is difficult to manage, simply tuck the food scraps under the mulch around fruit trees, it is still useful and will improve the soil over time. Worm composting bins work particularly well and can even be used in high rise buildings.
Soil-building strategies like green manuring and cover cropping rely on a unique ability of a group of plants, the legumes, to ‘fix’ nitrogen. Plants such as clover, lucerne, peas and beans have an important advantage over other plants, of being able to obtain nitrogen, a major element needed for plant growth, from the soil air. They do this by forming a symbiotic relationship with a group of bacteria called rhizobium, which live within a specialised structure, called a nodule, on the plant’s roots. The rhizobia can take nitrogen (N2) from the air and convert it to ammonium (NH4), the form of nitrogen plants normally obtain from the soil. This process is called nitrogen fixation.
Green manures are a cornerstone of ecologically sustainable gardening. These are annual fast growing crops, usually a legume combined with a grass, that are grown to build both organic matter and nitrogen levels to improve the soil. This combination works well, the legume providing nitrogen and the grass the bulk of the organic matter. ‘Grass’ refers to a cereal grain such as barley, oats or sorghum, not a weedy running grass like couch or kikuyu. When used in a crop rotation they can break disease cycles. They can provide outstanding benefits for the soil, crop and you, the gardener by:
- Increasing organic matter, earthworms and beneficial micro-organisms.
- Increasing the soil’s available nitrogen and moisture retention.
- Stabilising the soil to prevent erosion.
- Bringing deep minerals to the surface and breaking up hardpans.
- Providing habitat, nectar and pollen for beneficial insects and reducing populations of pests.
- Improving water, root and air penetration in the soil.
- Smothering persistent weeds; good choices for weed suppression include lablab, cowpea, lucerne and buckwheat.
Soil should never be left bare leaving it vulnerable to erosion and weed invasion.
Chemical fertilisers supply nutrients but no organic matter, so these nutrients are easily lost to the soil to become pollution in our waterways. The major advantage green manuring has over the use of inorganic fertilisers is it provides a sustainable source of nitrogen, an essential plant element. Green manures also increase organic matter levels. This in turn increases soil life by providing a readily available food source to the decomposing organisms. Inorganic nitrogen fertilisers are often produced from fossil fuels by polluting processes, which contribute to the greenhouse effect.
More information on green manure
Cover Crops and Living Mulches
There is no existing word in the English language to describe ‘a living carpet of perennial plants for use as an orchard groundcover’ so at Green Harvest we use the term ‘cover crop’ or ‘living mulch’ to describe this. The key word here is ‘perennial’, as green manures are annual plants. A ‘living mulch’ of low-growing perennial legumes can provide many advantages to the health of your orchard. First of all it can replace the grass which aggressively competes with your fruit trees for water and nutrients. Cover crops can also reduce compaction caused by frequent mowing; bring deep minerals to the surface and break up hardpans; provide habitat, nectar and pollen for beneficial insects and reduce populations of pests; and improve water, root and air penetration in the soil.
Growing a cover crop is particularly easy in new orchards as the soil can be cultivated. The seed is then spread as evenly over the area as possible followed by raking to cover the seed. In established orchards cultivating would damage the tree roots so a variety of techniques may need to be used. Poultry in movable cages can be used to bare the ground, which is then sown with seed. Alternatively an organic herbicide can be used to kill any grass. Or an area can be mulched with newspaper and hay until the grass has died, then raked and sown with seed.
- It is important to select both summer and winter vigorous ground covers to reduce weed invasion.
- Plant species should be selected for suitability to climate, ease of establishment, perennial habit, nitrogen-fixing capacity and shade tolerance.
- Avoid climbing legumes such as Lablab.
- Aim for a flowering meadow in your orchard rather than sterile, bare earth or a grass ground cover.
- Plant choices include Wynn’s cassia, barrel medic, red clover, white clover, lucerne, subclover.
Bare soil is a bad idea, it is vulnerable to erosion. Weeds are nature’s answer to protect the earth, so always try to get in first with mulch. No-one needs the additional workload of weeding when planting and sowing is so much more satisfying. Mulch will also improve your soil by:
- retaining moisture in the soil
- keeping the soil from over-heating
- preventing erosion and improving soil structure
- feeding the soil as it breaks down
- reducing the spread of fungal disease spores
- very importantly it can create habitat for soil dwelling predators, e.g. ground beetles and centipedes that control pests see Rough Mulch
Select different mulches for different areas of the garden. Mulch generally has a high carbon content so that it decomposes relatively slowly and won’t need constant replacement. High carbon choices include grass hay, straw and bark mulch. Sawdust is unsuitable due to its tendency to be water repellent and its usually acidic pH. If mixed with other materials it can be a suitable mulch under fruit trees. Eucalyptus bark mulches are useful under native shrubs, but may retard the growth of sensitive, non-native plants. Straw or grass hay mulches are useful in the vegetable garden. Gravel or pebbles are a good mulch for dry or fire-prone areas.
Using newspaper and cardboard as an initial layer of mulch will dramatically increase the period of time before weeds start to show through. A carpet of newspaper, part of the ‘sheet mulch’ technique, can be used where there are existing weeds and grasses, such as under a fruit tree. If the grass and weeds are long then start by mowing. Then spread an organic fertiliser or compost, make sure the soil is moist. Next tile the area under the tree with paper or cardboard, from the trunk to just past the dripline. This is a good way to reduce household waste paper entering the waste stream and instead return the carbon to the soil. Cover the scrap paper layer with mulch. There is no advantage to weeding first because the weeds will decompose and add to the organic matter. Even better, the roots of the weeds will decompose and add organic matter deeper down in the soil. The decomposed roots then become passageways through the soil for air and water to penetrate. Earthworms love the cardboard treatment and it encourages them to stay actively working to improve the soil for longer in the warmer weather rather than retreating to deeper, cooler areas.
More information on growing your own mulch
More information on rough mulch
More information on in-situ mulch
On very poor soils it may be difficult to grow anything, including a successful green manure crop. In this case the pH should be tested for excessive acidity or alkalinity, as this will interfere with uptake of nutrients by plants. pH is a measure of the acidity and alkalinity of the soil using a scale from 1 to 14; where 7 is neutral, less than 7 is acid and greater than 7 is alkaline.
Fresh, clean water is neutral with a pH of 7, vinegar is very acid with a pH of 2.6 and baking soda is very alkaline with a pH of 8.5. It is important to remember that pH is a logarithmic scale, so the difference between a pH of 7 and a pH of 6 is 10 times the acidity, between 7 and 5 is a 100 times the acidity and between 7 and 4 is a 1000 times the acidity.
pH can be used as an indicator of the availability of nutrients in the soil. Acid soils with a pH of less than 6 commonly have deficiencies in calcium, magnesium, phosphorus, potassium, molybdenum. Acid soils with a pH of less than 4 commonly have toxic amounts of aluminium and manganese. Alkaline soils with a pH of more than 7 commonly have the following nutrients unavailable; iron, manganese, zinc, copper, boron.
Adjusting the pH will make these nutrients available to your plants. Organic matter will generally ‘buffer’ plants against the impact of acidity so that a soil with a lower pH range will still successfully grow plants. Plants vary in their desired pH range and this is to do with the pH of the soil type they evolved in. For example, lavenders are native to the limestone soils of the Mediterranean and so prefer an alkaline soil.
More information on soil pH
Clay soils are high in nutrients but can be poorly drained, hard to dig and compacted. Most clay soils will be improved by the addition of gypsum, apply it at a rate of 500g/m2. Gypsum (calcium sulphate) does not alter the pH of the soil but can improve aeration and reduce compaction in a clay soil. Avoid walking on or digging clay soils when wet. Keep well mulched and apply large amounts of organic matter. Over time, as the organic matter decomposes and earthworms proliferate, the soil will become lighter and easier to work. Green manures to particularly improve clay soils include: fenugreek, cowpea and lupins.
Sandy soils are easy to dig and well-drained but are low in nutrients and dry out quickly. Adding organic matter to act as a sponge and hold the nutrients and water in the soil is critical. Keep the soil well-mulched as the slow breakdown of nutrients helps buffer the impact of leaching. Sandy soils are worth the expense of a lucerne mulch. As the lucerne decomposes it will form a loamy topsoil on top of the sand. Over time earthworms will blend the layers creating a better soil. Green manures to particularly improve sandy soils include: buckwheat, millet, oats and woolly pod vetch.
Crop rotation is a useful strategy for vegetable gardens as it prevents the build-up of soil-borne diseases and balances nutrient uptake. This is the practice of growing vegetables from different plant families in beds the following year. So tomatoes, potatoes or eggplants would not follow each other as they all belong to the same plant family, Solanaceae. Sadly it is a garden myth that you should follow a crop of peas and beans with a heavy feeder like cabbage, because of all the nitrogen fixed by the legumes. This is true in Europe where these plants have originated but unfortunately not true in Australia where the symbiotic bacteria are generally not found in our soils, unless an inoculated crop, such as a green manure, has been grown within 3 years. Generally peas and beans grown as vegetables have the same need for nitrogen as any other crop and do not leave a residue of additional nitrogen for the next crop.
Many Australian soils are deficient in a range of macro and micronutrients, all equally necessary for plant growth. The addition of composted animal manures or products such as Dynamic Lifter, will increase the supply of macronutrients such as nitrogen, potassium and phosphate. Trace or micronutrients are only needed in small amounts but are just as important for healthy plants. Trace elements include calcium, magnesium, sulphur, iron, manganese, copper, zinc, boron and molybdenum. Initially in deficient soils it may be necessary to apply a trace element mix, but ongoing nutrients can be supplied by fish emulsion or a seaweed fertiliser such as Natrakelp
The aim in applying fertilisers is to create sufficient fertility for initial growth. During periods of continued heavy rain, the leaching of some nutrients is inevitable. To keep plants healthy and growing vigorously at these times, the application of seaweed fertiliser as a foliar feed is recommended.
Life is solar-powered, only plants can photosynthesise, transforming the sun’s energy into carbohydrates