I've been reading posts in the group about trying to get clay soil in a
Most people seem to be at the general consensus that you need to add gypsum,
peat moss and sand, along with other organic material. But someone mentioned
that before you go adding too much stuff to it, you should get the soil
tested for ph balance, to make sure you don't make a bad problem worse! My
question is...how do you test the soil? I'm fairly knew to gardening in
general, I used to just potter around at home with my parents, however now I
have my own place, with very very thick clay soil!
I just bought a detector this year for 30 usd. Not totally convinced of its
accuracy. AAMOF I'm kinda confused by the whole concept: bitter is not the
opposite of sour in my mind. I guess below 7 is sour; above 8 is bitter;
but in the 7 range is sweet? I have slightly bitter Hawaiian soil, but have
been composting of late. AIUI different plants have different values for
ph. Post what you're likely to plant and I'll try and see the target range.
Sand is a good drainage system for thick soil, but I would be weary of
adding it (atleast from the beach) as the salt would presumably drive up ph
levels. I remember reading somewhere that they were doing that in Ireland
right before the potato blight set in. Does 'thick' soil mean you have
puddling? Composting is supposed to remedy that.
Testing is usually done by professionals from a sample (or better,
multiple samples) you provide. The samples are generally small,
less than a trowel-full. Ask about testing services at your local
nursery. In some areas, the county or state agricultural services
It's obvious from several of the replies in this thread that many
do not know the purpose of soil testing. It's not merely to
determine the pH. It's to determine the overall quality of the
soil. Beyond pH, this includes the relative abundance of
nutrients, not only the primary NPK (nitrogen, phosphorus,
potassium) but also trace elements such as iron, zinc, magnesium,
etc. A good soil test will also determine salinity, which is
important in the western U.S. where both soils and water supplies
might contain excess sodium. Finally, a soil test should determine
the structure (i.e., relative proportions of sand, silt, clay, and
Since trees, shrubs, and even some perennials can send their roots
well below the level where you have tilled amendments and
nutrients, you should test the native soil before doing any
improvements. (In deep soil, tomatoes can send their roots down 10
feet.) For example, adding gypsum before testing will definitely
skew the results and prevent you from learning what the roots will
eventually find. The results might indicate certain improvements
are not necessary while others are indeed needed. Why spend money
and effort before you know what needs to be done?
If you live in an area where government agricultural agencies do
not do testing, there are likely to be commercial testing labs.
Even in the U.S., not every county has an agricultural extension
office; and in those that do, not every agricultural extension
office does soil testing.
David E. Ross, President
Community Foundation for Oak Park
There are many levels of soil testing out there. You have to choose the
one that's most important for your particular situation. Of course, the
more things you test for, the higher the price.
The home soil test kits can provide a good estimate of pH. (By a good
estimate, I mean that it can tell you if the pH is 5 or 6 or 7. The
laboratory test will get you down to a couple tenths of a pH point.
However, for most home gardens this level of detail is not really
important.) Phosphorous and Potassium are probably so-so. Nitrogen is
probably not worth the effort.
The soil structure can be estimated by observing the soil and its
response to large doses of water. High sand components drain quickly.
High clay components don't drain. Assuming the soil is not really high
in clay or sand, the loam content can be estimated by taking a handful
of moist, but not wet, soil and squeezing it into a ball. If it forms a
crumbly ball, it's probably moderate loam and sand. If it forms a hard
ball there's probably heavier in loam and clay. This all takes some
experience, but then knowing what to do about your soil structure also
takes some experience. Observing your garden over a couple of years can
give you some insight into this.
Of course, having a professional do the tests also allows you to get the
advice on what to do with the results from the professional.
To do a soil test:
Take a small sample of soil from several different locations in your
garden and mix them thoroughly. Take samples from the surface to at
least 6" deep, and if you plant deep rooted crops, a foot wouldn't hurt.
Don't be tempted to buy a soil testing probe for a home garden. They
cost like $50. You can make your own. A 10' piece of 1" EMT conduit from
Home Depot (about $3). Cut a reasonable length off so you can handle it.
Jam it into the soil. You will get a core sample. You can get it out by
shoving something through the conduit. If you know an electrician, (s)he
might have a scrap piece. 3/4" conduit will work.
Dry them out. The testing lab needs them dry for the test and you don't
need to pay the postage for the water that they are going to get rid of
(not to mention that it increases their work load if they have to dry
all the samples.) You can dry them out by just spreading a pile of soil
on an old newspaper in the garage (fairly thin) for a day or two. Don't
dry them with a lot of heat. That will alter the organic composition of
the sample. The testing lab will let you know how much they need (It
will depend on the number of tests), but it'll probably be on the order
of a sandwich bag or so.
Tell the lab what you are planning to grow. This will enable them to
make specific recommendations on addition of lime, fertilizer, other
David Ross wrote:
Purchase a pH test kit from the garden department. Compost will help
neutralize any soil, plus add nutrients. Gypsum is a good idea but I
would not add sand nor peat moss.
On Wed, 16 Jun 2004 17:08:48 +0100, "Ben Blackmore"
What are you trying to grow? If you just want flowers or vegetables, the
easiest way to get good soil is with Square Foot Gardening. It's a proven
system, and you can get all the info you need free at
http://www.squarefootslo.com and see what it is all about.
If you want to grow shrubbery, etc., then you don't have to worry about the
soil quality. Just dig out a larger area than the plant needs and fill the
extra area with good soil. Then make some bricks with the excess clay and build
a barbeque with it lol.
Certified Square Foot Gardening Instructor
Learn to be a freelance web designer http://www.howtofreelance.com
You should get your soil worked up using the materials you mentioned
before getting a soil test. You want to test the soil you are going to
plant in, i.e. the finished product. For example, gypsum will probably
change your soil's pH so you want to test it after the gypsum is in
Don't waste your money on a DIY soil test kit! The agricultural
professors at a local major college did a study of numerous different
DIY kits from various retail outlets. Many soil samples were checked
with the kits and then checked against their lab equipment. The
results varied drastically, some not even in the same ballbark.
Here's what you need to do. In the garden to be tested, take a sample
from 5 or 6 different places in the garden/yard. Take about a cup of
soil 6 inches below the surface at these points. Mix all the samples
together thoroughly - this gives you an average for the whole garden.
Put about 2 cups of this mixed soil in a baggie and take it to your
local Extension Service office. They should be listed listed on the
phone book under County Government. Price usually runs from $5-$10.
Tell them what you intend to grow in the spot -flowers, vegetables,
grass, etc. They will send it to a lab for analysis. They will mail
you a complete detailed analysis, not just pH level, with instructions
on how to correct any deficiencies.
Good luck on your project.
Would it be an idea to test it twice, once before then once after, otherwise
I won't know how much of each material to add. I could end up making a bad
situation worse if I add too much of one and not enough of the other. If I
were to test it 1st, and got an idea of what needed to be done, then I could
test after as well and make sure it worked.
Make sure you delay your second test by a few months at least.
Don't try and "correct" your soil. That is like bumping your head
against a brick wall. Rather let the pH determine what you should
and should not grow. Any mineral deficiencies may be made up by using
a standard balanced fertiliser like "Growmore" regularly. Even though
only the N,P,K concentrations are mentioned in the specifications
given with the fertiliser, it will as a rule have been made from
sufficiently impure materials to supply sufficient trace elements as
I have used the chemical pH test sets available from garden centres on
many occasions. I have compared the results with measurements using a
professional pH meter. The results always agreed well enough for
gardening purposes. The bad errors invariably arise from poorly
chosen samples, bad preparation of the samples and the use of tap
water or rain water instead of deionised or distilled water
What is a local Extension Service office?
There is no entry "County Government" in my phone book
The US Dollar is not legal tender in the United Kingdom.
What on earth are you talking about?
Because I wanted as much input as I could get. Most of what the US replies
said were still valid and very useful! Just because one of them mentioned
USD rather than GBP does not make it an invalid post. The input on soil
composition and ph levels was all very useful!
Ben Blackmore ( firstname.lastname@example.org) wrote:
: Because I wanted as much input as I could get. Most of what the US replies
: said were still valid and very useful! Just because one of them mentioned
: USD rather than GBP does not make it an invalid post. The input on soil
: composition and ph levels was all very useful!
But you might want to ignore the advise to add coffee grounds to the soil.
Works ok, I'm told, in the southern US. Just adds an extra bit of material
for moulds to grow in wet, humid climates like here on the we(s)t coast
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