"Advice… advice… advice…. Some of it suggests one thing and some of it says just the opposite. Most of all it is very good advice… for someone. But not all of it turns out to be good advice for you.
Why is that? It is simply because your garden and your gardening style are unique. You can't expect your work glove to fit perfectly on someone else's green thumb".
- Lois Levitan, Improving Your Gardening with Backyard Research, Rodale Press.
Many people approach me for advice after they have purchased their land. All too often, it is not very well suited to what they want to do. However, all except the worst sites can be improved to the point of being productive.
The best soils for gardening are loams, light soils are second best and heavy soils worst. This needs some qualification. Loam is balanced soil. Light soils consist mostly of sand making them hungry and drought-prone, but they produce crops earlier than the other two soil types and can be worked even when wet. Heavy soils consist of mainly silt and/or clay so they tend to be very fertile, but they warm slowly in the spring and should not be tilled when wet. The writer's soil is very heavy and a friend's market garden referred to often throughout this book started out as almost pure white sand.
Vegetable gardens need shelter from the wind. If this shelter does not already exist, then windbreaks will probably need to be established before you can commence gardening. Artificial windbreaks can be made, but they are rather expensive. As well, they do not harbour predators like a properly designed windbreak of trees and shrubs.
The aspect is very important. The soil needs as much sun as you can provide and a north-easterly slope will warm quickest. In warmer districts, a north-westerly slope that warms slower might be better. Note that these recommendations are for the Southern Hemisphere.
Rainfall is another important consideration. The worst situation is too much rain. It leaches nutrients and causes erosion and fungal disease problems. While a dry situation can be ameliorated by irrigation, the dissolved salts in groundwater can accumulate in many soils, eventually poisoning them. The best situation is one of moderate rainfall with adequate supplies of water of reasonable quality to supplement the rain.
Land that is too level will create drainage problems and accumulate cold air. Land that is too sloping will cause erosion unless terraces are created. Terracing is expensive and the extra effort required to move produce and compost up and down the slope will consume a lot of energy. Land of moderate slope allows good drainage of water and in frosty districts, cold air.
For market gardening, you will need good access to the road and sheds. As well, you will need ready access to a market for your produce. Most important of all, you will need a source of inexpensive compost ingredients.
When we were looking for our land, we only knew that we wanted to be within commuting distance of our state's capital city and the land must be sandy. In the event, we discovered that good land was very hard to find. Farmers are not stupid; they prefer to subdivide their least productive land for sale to hobby farmers. We ended up with heavy soil, rather than sand, or loam. The property is gently sloping, so it drains well (for heavy soil) and there are no frost pockets. Our water source for irrigation is at the top of the slope, so we can use gravity for irrigation, rather than expensive and unreliable pumps. Unfortunately, it is a runoff dam, not on a permanent water course, or spring. One winter it failed to fill. One summer, we emptied it six weeks before the first autumn rains.
One potential problem for us as organic producers was spray drift from our neighbour's property. When we first moved in, we were surrounded by cattle pasture. Some two years later, our neighbour established an apple orchard on the windward side. The first time the tractor driver sprayed the young trees, The Git approached him and thanked him for spraying when the wind blew the spray away from our property. Ever since, he has always taken our needs into account.
Good fences make good neighbors. - Robert Frost
It is easier to love humanity as a whole than to love one's neighbor. - Eric Hoffer
There is a bewildering number of methods of growing vegetables. Many books have been written extolling the virtues of no-dig, mulch, raised beds, circle gardens and many more. This book draws on some aspects of many of these ideas. The systems The Git advocates are based on the concept that if you are to make a profit from growing vegetables, then time management is of the essence. Even if your "profit" is "only" money saved on shop-bought produce, the same principle still holds.
As an example, let's take carrots. On average, The Git's organic fertiliser costs have been a mere 2.5% of the gross return for all crops combined, so the critical profit factors are time consumed and yield. Typically, 50%, or somewhat less of the time to produce a crop is spent actually growing it and 50%, or somewhat more is spent harvesting and marketing.
There are three basic methods of growing carrots. The first is growing them in single rows spaced 300 mm apart with 75 mm between plants. This is the conventional method. It has several disadvantages. The wide row spacing is to allow the gardener room to hoe, weed and harvest the crop. The continual traffic between the rows compacts the soil, reducing yields. It works poorly in shallow topsoil - carrots prefer deep soil. Heavy rains can wash the soil badly, leading to incomplete rows.
The second method is to grow the carrots on raised beds, 1.2 m or so wide and 100-150 mm high with 400-500 mm wide permanent footpaths (or tractor wheel-ruts) between. The carrots are sown in rows along its length, the plants 75 mm apart and the rows 150 mm apart. The yield per unit area is higher than with the first method, because the soil is never compacted by being walked on and water and air infiltration is improved. Topsoil depth is also greater, allowing more soil for nutrient exploitation. Yields are generally 50-100 % higher per unit area than with method one.
The third method, advocated by John Jeavons in his excellent book How to Grow More Vegetables (10 Speed Press), is to sow the carrots 75 mm apart each way across the raised beds used in method two. This has all the advantages of method two, but two disadvantages. The first of these is related to sowing. It is difficult, though not impossible, to sow seeds in drills 75 mm apart. Jeavons advocates broadcasting, or sowing individual seeds on 75 mm centres. Broadcasting is quick, but it's very difficult to ensure the seeds are evenly covered with soil so that they germinate simultaneously, most important in close planting. Thinning the crop is very slow. Sowing on 75 mm centres is also slow, but means that minimal thinning is required. The second disadvantage is that weeding cannot be done with a hoe; it must be with fingers. It should be pointed out that in moderately weed-free ground, that only one, or two finger-weedings are required, as the plants quickly close up the space between and the leaves suppress the light reaching any late germinating weed seeds. The yield from Jeavons' method is as much as 50% greater than method two.
Method two is easily the most time efficient and yields are excellent. The rows are readily sown with a mechanical seeder and a narrow hoe is used to remove most weeds very quickly. We estimate that method two consumes less than 50% of the time per kilogram of carrot produced when compared to methods one and three.
Gardeners who like to use mulch on crops such as carrots that require a constant level of moisture will have noted that Jeavons' method is not adaptable to mulching. Jeavons points out that the leaves of the crop plants rapidly grow to shade the soil, forming a living mulch. Method two above, like method one, is conducive to mulching after seedling establishment, but also creates a living mulch as in Jeavons' method three, albeit more slowly.
Raised bed gardening actually pre-dates row gardening. Row gardening was developed following the publication of Jethro Tull's Horse Hoeing Husbandry in the seventeenth century. The Tullian row cultivation method was developed for grain production, quickly supplanting the broadcast method. Weeds that previously needed to be pulled by hand were quickly controlled by either horse, or human powered hoes. What we have done is adapt the best of both systems. In conventional row cultivation, 50% of tillage is only required to undo the damage caused by soil compaction. The advantage of row cultivation, speed of hoeing for weed control, is retained.
Soil consists of a mineral fraction, water, air and organic material. The ideal soil for growing crops is 50% solids, 25% air and 25% water when all excess water has drained away. The organic material should be 5%, or more, of the total solids. The mineral portion is subdivided into silt, sand and clay particles. The organic material can be subdivided into living and dead, or raw and humified.
The relative proportion of the three mineral solids determines the workability of the soil. Silt and clay particles are very tiny. Where they predominate over sand, the soil is said to be heavy. It contains little air and holds onto a lot of water because of the huge surface area of the soil particles. Tillage tends to be rather difficult. Where coarse sand particles predominate, the soil is said to be light because it's easy to till. There is an abundance of air, but little water holding capacity. The best soils from the point of view of the vegetable producer have a balanced proportion of all three mineral types and are classified as loams. However, even the most unpromising soils can be improved to the point of economic productivity. We will look at two market gardens closely in this book. The Git's own soil is silty clay and that of his good friends, Ian and Caryl Cairns started out as almost pure white sand.
Clay particles are rounded, as well as very small. They pack together very tightly and make the soil feel sticky. Clay particles also carry a negative electrical charge so they attract positively charged elements and compounds such as the essential crop nutrients: calcium, magnesium, potassium, ammonium, molybdenum and sodium. These positively charged materials are called cations (CAT-EYE-ONS). The amount of these elements a soil can contain is called its Cation Exchange Capacity (CEC) and this is a good measure of its fertility, or capacity to produce. Cations held by the negative electrical charges on the clay particles cannot be easily leached from the soil by rainfall, or irrigation. They are made available to plants when plant root hairs emit positively charged hydrogen ions, which displace the cations.
Silt particles, while the same size as clay particles, are flattened rather than rounded. Like clay particles, they also pack together very tightly, but make the soil feel silky as the flat plates readily move against each other. Unlike most clay, silt contains a variety of nutrients that are made available to plants through biological activity. Silt is formed by the action of glaciers on rock and the bulk of silt on the planet is formed during the great ice ages. Australia's soils are some of the oldest in the world and therefore contain less of these plant nutrients. In any event, it is a rare silt that contains an ideal balance of nutrients, so nutrient supplements are nearly always called for.
Sand particles are large and so sand has large gaps when it is packed. They make the soil feel gritty. While they contain negligible amounts of plant nutrients and lack clay's ability to hold onto them, they improve the soil's drainage and air holding capacity.
Organic matter falls into two categories, living and dead. The dead material is a source of plant nutrients as it decomposes. Bacteria can convert it to a material called humus. Humus acts as a sponge for water, so it improves the water holding capacity of sandy soils. By holding silt and clay particles apart, it improves the drainage and aeration of heavy soils. They also become much easier to till. Like clay, it also carries negative electrical charges and so contributes to Cation Exchange Capacity. Increasing the humus level of a soil is the only economically realistic way to improve the Cation Exchange Capacity and consequently yield potential.
Fungi can also decompose organic matter. This process produces alcohols and other growth inhibitors, rather than humus. One of the key differences between organic and mainstream cropping is the organic grower endeavours to promote humification in the soil, consciously, or otherwise. Conventional growers in the past were trained to ignore soil biological processes as relatively unimportant. The best known example of humification is the process of composting. This is a major topic and so has its own chapter later in the book.
The living components of the soil include fungi, bacteria, actinomycetes, insects, plant roots, earthworms, nematodes, algae, viruses and protozoa. OK, The Git knows that viruses aren't classified as being truly alive, but they do qualify as part of the living system. There is no living system that is free of virus and there are new candidates for living organisms as this is written: nanobacteria. Fertile soil supports at least as much living matter within it as we can see above the soil surface. The sheer number and variety of these organisms is mind-boggling. A teaspoonful of living soil contains billions of microbes, most varieties of them remaining unknown to and undescribed by science. In organic production, the balance between them is the primary concern. Fortunately, we do not need to know very much about the many complex interactions between them - they are very good at managing such things themselves. A few simple principles, mastered by peasant farmers throughout the world, are all that is required.
While conventional agriculture has been obsessed with the most obvious part of the plant, the above ground parts, these are fed by a complex root system. The roots take up the mineral nutrients, nitrogen, phosphorus, potassium, sodium, calcium, magnesium, trace elements and water that the leaves require to convert carbon dioxide into sugars, starches and other carbohydrates. The roots have short protrusions called root hairs that are responsible for nutrient uptake. Their health requires adequate moisture and air, hence the earlier prescription for healthy soil being 50% solids, 25% air and 25% water. Too much water and too little air is a common cause of plant ill-thrift.
Many plants have fungi that live part in the soil and part in the root that exchange phosphorus from the soil for carbohydrate from the plant. They are called mycorrhizae and some plants cannot survive without their particular mycorrhiza. Many others exhibit poor productivity without them. Another example of symbiosis is that between the nitrogen-fixing bacteria called rhizobium and legumes. Rhizobia live in nodules on the roots of the plant species we call legumes. They convert nitrogen from the atmosphere that plants cannot use directly, into protein. The legumes include clover, lucerne, beans and peas.
The single most important soil organism is the earthworm. The health and vigour of this muscular tube of protoplasm is the best indicator of overall soil health. If there are no earthworms, then plant productivity is but a small fraction of its potential. There are two main types of earthworm, the manure worm and the pasture worm. Manure worms require copious quantities of protein-rich organic matter and do not ingest soil. The pasture worm requires much less organic matter and ingests soil. The worms sold by worm farmers are manure worms and are less important from the standpoint of the gardener than the pasture worm.
The gut of pasture worms transforms the minerals in the silt particles they ingest into useable plant food. As well, their excreta, called worm-casts, are small crumbs that are just double the diameter of the length of a root hair. These crumbs are essential to the open structure of fertile soil and are easily damaged by excessive tillage. In point of fact, earthworms perform much of the tillage in organically managed soil. This concept, taken to its extreme, has led to what is called no-dig gardening. While this is an option for the home gardener, it is generally too unproductive and costly for the commercial producer.
While the manure worm is relatively unimportant in the soil, it comes into its own when used for converting bulky organic matter into a special compost called vermicompost. This is discussed further in the chapter on composting.
Almost every newcomer to gardening, including myself, have bitten off far more than they can chew. A little planning and a considered approach will considerably reduce the toil and cost. For the home gardener anxious for the joys of fresh produce, a small area can be set aside to play with, but the main part of the garden is best approached more carefully. First, decide on a crop rotation that will provide for your needs and those of the crops you wish to grow. You will find the information you need in Chapter ???. An area needs to be set aside where compost can be made, raw compost materials stored and a shed, or other storage place for tools. Next, the area needs to be fenced against marauding predators where that is necessary. Humans are the most difficult to keep away and possums almost as bad. Finally, the growing area must be cleared of unwanted vegetation.
Compost is best made in a shady area, sheltered from drying winds and free of weeds. In the home garden, two cubic, open-faced bins of a little over one cubic metre capacity are all that will be required, unless the garden is very big - in that instance, an extra bin, or two is usually better than making the bins over-large. For the market gardener, compost can be made in long windrows, between one and two square metres in cross-section and as long as required. If you plan on compost materials decreasing in volume by 50% and compost taking three months to be ready from the raw materials, you will be able to calculate how much area to set aside. A cubic metre of compost will cover 40 square metres to a depth of 25 mm, the recommended amount of average compost for the average crop.
Australian gardeners are notorious for leaving their tools outside in the rain and sunshine. This severely reduces their useful lifespan. Providing a place where tools are protected from the elements and are readily found can save much money and lost time.
Frankly, The Git has been putting off writing this section until the last. To him, fences and fencing are bothersome and boring, BUT they are nearly always a critical factor for successful gardening. A successful garden contains crops that are attractive to a variety of potential predators who will happily consume all the products of your labour if you let them. First, know your predators; what works for rabbits won't stop a human; what works for dogs won't necessarily stop goats. In fact, keeping goats out ranks alongside stopping humans, as both seem able and prepared to devote all of their ingenuity and skills to stealing garden produce.
Having prepared your list of potential known predators, take the list to either a competent fencing contractor, or a rural supplies store that services farmers' needs. The latter can not only supply the raw materials needed, but will have literature to ensure you get the best out of what you purchase should you decide to save money by building your own fences. Skimping on fence quality is A Very Bad Decision since it means you will have to re-fence sooner or later. If there's one thing worse than fencing, it's having to replace after a short time what should have sufficed for decades.
This isn't primarily a fencing manual, but it's worth touching on several important fencing issues that are not apparent to the fencing neophyte. The most important part of most fences is the end assembly. Many fences are merely held up between the end assemblies by the tension on the wires, or wire fabric between. This is not just because it reduces the cost of intermediate posts, but also withstands pressure from livestock better. Rather than gradually falling over from continuous pushing, they spring back into place following a push.
The strength of the end assembly is determined not by the diameter of the posts used to make the anchor, but their depth. An increase in depth of 300mm approximately doubles the strain that can be exerted on a post! Posts that are driven into the soil with a post-driver can take much more strain than those placed in a hole and backfilled.
Steel and copper-chrome-treated pine posts will last many times longer than untreated hardwood posts. Even if the hardwood posts are free, they will usually cost more in the long run as they usually decay and become useless in a few short years. Copper-chrome treated posts are much cheaper than steel, but if they burn, the fumes are toxic. Better to make sure they don't burn. If animals chew on the treated posts, look to the animal's nutritional needs rather than worrying about the possible effects of the copper and chromium! Insufficient copper and chromium in the diet should be a cause for concern and likely readily amended with kelp meal, or appropriate mineral blocks.
The home gardener can mulch weedy ground, or lawn with cardboard covered with straw, or hay starting in winter. This will slowly rot the turf, leaving soil beneath that will be easily tilled the following spring. During this period, compost can be made in the bins you have made. In late spring, the largely decomposed mulch can be placed in the compost bin to start your next compost heap. The compost you have already made can be spread over the whole area you intend to garden. Do not worry if this is less than a 25 mm cover; it is better to spread your compost over the whole area than to concentrate it on a lesser area.
You should then till the soil to incorporate the compost and commence the lengthy task of reducing the perennial weeds and dormant weed seeds to a manageable level. The soil can be broken up initially by spading, forking, or rotary hoeing. Subsequent cultivations are better done with a hand-hoe, or wheel-hoe. By lightly tilling once every week, or two, the roots of perennial weeds, such as couch grass (twitch) and dock, are starved and exhausted. Each pass with the hoe also allows another batch of weed seeds to germinate and their numbers will decrease. Many of these weed seeds have hard seed coats, so they will continue to germinate for a number of years, but this initial phase, called a summer fallow, will make your life much easier than if you were growing a crop. The time to till is when the weed seedlings are at what is called the "white-wire" stage. This is when only the seed leaves have emerged and before the first pair of true leaves.
A refinement is to sow a smothering crop and till it in. Suitable crops include mustard and buckwheat that germinate and grow rapidly. Weeds then germinate under the heavy shade of their leaves. This is only useful if there are no vigorous perennials, such as dock, sprouting from large root pieces.
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© Jonathan Sturm 2003 - 2011