This is the only home soil test kit you really need

If you see an ad for a cheap home soil test kit, don't be fooled - they really don't tell you very much about your soil. Even those that give reasonably accurate results will only look at the major nutrients (Nitrogen, Phosphorus and Potassium) and pH.

If you have been reading through the information on this site, you will surely see that such limited information is almost useless - especially if you are interested in organic soil improvement. So the only real "home soil test kit" you need is the information on this page.

However, the first problem you will face is that most of the soil testing laboratories in the World focus on agricultural analysis. This may sound fine, but there are differences between a farm and a garden. For one thing, farms tend to be rather large. If you got a farm soil test, you would then have to convert their recommendations from lb/acre or tonnes/hectare to the equivalents for square yards or square meters.

Farms also tend to grow only one thing. Even those trying to break out of the monoculture mold are likely to have only 2 or 3 productive land-uses. Gardens on the other hand, need to care for dozens - if not hundreds of different plants.

On the plus side though, there is one laboratory that is trying to do things differently. SWEP Analytical Laboratories has been supporting farmers around the World since 1980 and has just introduced a unique 'Home Garden' version of its soil testing service.

There will be more information about this a bit further on, but before you even start worrying about laboratories, you first need to collect a good sample. Again, this is something the makers of many home soil test kits tend to skim over, but the fact is that soil is highly variable stuff. So a pinch of soil from part of the backyard cannot hope to give you a reliable result.

So here is the first tool in your home soil test kit:

Collecting garden soil samples

Soil sampling is the most misunderstood aspect of the whole process. A soil test is only ever as good as the sample you send. As mentioned earlier, this is another reason why a home soil test kit won't work - soil is way too complex and variable for you to ever get a representative result from a pinch of soil you got two steps away from the back door.

In fact, the term 'representative' is one to get used to. The soil in your garden will vary from place to place, so you need a sample that gives you a realistic "representation" of the overall condition of the soil. In other words - a general picture or a working average.

Never make the mistake of thinking in absolutes. For example, a Phosphorus test result of 24 ppm (parts per million) does not mean you have exactly that amount in every part of your garden. If you had taken a representative sample, it would mean that in general terms - across the area you sampled - you have an average of this amount available for plants to take up. Some parts of the garden may have only 20 ppm, but the vegetable garden may have 30 ppm or more.

Of course, if you used a pinch of soil from a spot 5 feet from your back door to get a result from a home soil test kit, then the result would apply only to that particular pinch of soil!

So a representative sample is one thing, but what is it representative of? - The whole garden? The lawn areas? The vegetable garden? If different parts of the garden are used differently, then they should be sampled separately.

Fortunately, SWEP has a good page on collecting garden soil samples, so I don't really need to bore you about this any more than necessary.

The next part of the home soil test kit is to consider your land uses.

Gardening "Land uses"

You can improve any soil in 5 steps, but every plant species has its own unique requirements for balanced nutrition. Of course, if you were to get the fertilizer requirements for all the plants in your garden, the soil test report would look more like a volume of the "Encyclopedia Britannica"

Fortunately, many plants can be fitted well enough into a number of groups to help simplify the situation. The following nine groups will cover most situations in the garden:

1. Ornamental plants
• Lawns
• Trees and shrubs
• Flower beds
2. Fruit and Berries
• Pome fruit (apples, pears, quinces, etc.)
• Stone fruit (peaches, apricots, cherries, plums, etc.)
• Berries
3. Vegetables
• Leafy vegetables (lettuce, cabbage, etc.)
• Fruiting vegetables (tomato, capsicum, etc.)
• Root vegetables (potato, onion, etc.)

You should select the groups from this list depending on your situation. For example, if you have an established garden you will probably sample from existing areas (say the vegetable garden) and so only select the groups that suit this area of the garden.

Of course, if you are starting a new garden from scratch and have yet to decide what will go where, you could take a more general sample across the whole area and perhaps choose one from each group to give yourself a more general idea of requirements.

But what if you are a specialist gardener - one who is devoted to the culture of particular plants? Let's say your passion is Rhododendrons and Camellias. The really neat thing about the SWEP garden soil test is that you really only need to choose one of the groups above. The other two "land uses" (there is a maximum of 3 per report) can be selected from the more than 200 plant types they have on their system that are normally used by farmers, flower growers and nurserymen. So you could also choose: "Trees and shrubs" plus "Rhododendron" plus "Camellia".

Need information on more groups or plants? Then simply order more than one report from the same sample. Let's say you are a Rhododendron and Camellia enthusiast with specimen plants arranged beds with flowering perennials, Daphne and hydrangeas. In addition to the report described above, simply order a second report (using the same set of test results) for "Flower beds" plus "Daphne" plus "Hydrangea".

Now you almost have a complete home soil test kit. But you still need something to collect the sample with, a useful test to get and a way of sending your sample to the laboratory.

Soil sampling tools

For detailed soil analysis that includes trace elements, you must be careful what you use to collect the sample. Many metals can contaminate the sample with elements like copper or zinc. For this reason, you should only ever use a stainless steel coring tool, but the ones used by farmers and soil scientists can be rather expensive.

However, a good alternative for gardens and a useful addition to your home soil test kit is a stainless steel apple corer that you can get for only a few dollars at your local supermarket. Naturally, this will not be as sturdy and so will only be good for one or two samples, but it is often the cheaper and more convenient option.

An Organic Gardening soil test

With a home soil test kit, you get a few simple tests. You can get more detailed results from a laboratory, but there are all kinds of soil tests from all kinds of laboratories.

By far the best soil test currently available (and developed specifically for gardeners) is the Organic Gardening soil test from SWEP.

This test includes all the cation balance tests and recommendations described in reading reports, together with analysis and recommendations for all essential plant nutrients - Nitrogen, Phosphorus, Potassium, Sulfur, Calcium, Magnesium, Sodium, Copper, Zinc, Iron, Manganese, Cobalt, Molybdenum and Boron. Other tests also included are pH, salt levels (known as EC, which stands for electrical conductivity) and organic matter.

Uniquely, this test also includes Soil biology testing, plus Total Phosphorus, Total Nitrogen and Carbon-Nitrogen ratio.

This is the test to use if you want to make sure the grass is always greener on your own side of the fence.

Packaging and sending your sample

Of course, the one advantage with a home soil test kit is that you don't need to send off your sample and wait for the results to come back. Don't worry, the effort of sending your sample and the time spent waiting for results really is a very small price to pay when considering how dramatically a good soil test can help you improve your soil.

If you live in Australia, SWEP can send you a free sample kit that has sample bags, an Express Post satchel and instructions. Of course, you don't really need one of these kits - it is just as easy to do it yourself. Use a press-seal or ziplock plastic bag (sandwich sized) to hold your sample and a box or padded envelope to send them in.

You will also need to enclose your contact details and information about the samples, so print the appropriate sample information form from the SWEP website and you will then have all the parts of the only home soil test kit you really need.

If you are not in Australia, the process is essentially the same, however, it is important to address the samples to the street address for SWEP - not their Post Office Box number. You will also need to write their Quarantine Permit details clearly on the outside of the package.

Now you have a complete and reliable home soil test kit - or at least the only one you really need.