SOIL TEST KITS
Soil test kits are available from your local Penn State Cooperative
Extension office. In Allegheny County, soil test kits are $12 for
the first kit and $9 for additional kits ordered at the same time.
They come with complete information for taking representative
samples and understanding your soil test results. You can send a
check for the cost of the number of kits you want to Penn State
Extension, Soil Test Kits, 400 North Lexington Street, Pittsburgh,
PA 15208. Make checks payable to Penn State Extension.
Soil test results
Once you purchase the
soil test kit, take the sample and fill out the paperwork, and
then send it to Penn Stateís Agricultural Analytical Laboratory. The
fee covers the cost of the kit and the actual testing. Your only
other cost is the postage to send it to the university. The kit is a
self-contained mailer with the correct address pre-printed on it.
Penn State soil tests evaluate the level of phosphate, potash,
calcium and magnesium, as well as the
pH (acidity or
alkalinity) of your gardenís soil. The lab does not test for
nitrogen since the level of nitrogen in the soil changes so rapidly.
Nitrogen can be lost to leaching, volatilization and/or runoff.
Nitrogen recommendations are based on the known needs of the crop
you are growing.
Community vegetable garden
You should have separate tests done for the flower beds and the
vegetable garden. If you wanted to have the soil in your lawn
tested, that should be a separate test as well. The reason for
separate tests is that different crops have different nutritional
requirements. These differences determine the soil labís
It is a good practice
to incorporate organic
matter, such as mushroom compost, into your garden soil
annually. Organic matter improves the structure of the soil, which
permits greater aeration, water penetration and improves drainage in
our clay soils. It creates a favorable environment for microbial
action and insect activity, which aerate and enrich the soil.
Organic matter also increases the soilís water and nutrient holding
Compost adds organic matter to soil
The only harm may be in using mushroom compost year after year.
Mushroom compost tends to have a moderately high pH, around 8.0.
Your soil test will reveal if adding mushroom compost every year has
raised the pH of your soil above what most vegetables prefer,
between 6.0 and 6.8. If so, your test results will include
instructions to use sulfur to lower the pH into a more suitable
range. I would not add any limestone until you have your soil tested
to see what the pH is now, since limestone will only raise the pH
more. You can alternate using other sources of organic matter, such
as homemade compost, aged manure, composted grass clippings (not
treated with herbicides) and/or shredded leaves. Mushroom compost is
a very good soil amendment. Just temper its use with the knowledge
that itís high pH and soluble salt content can throw off the balance
of your soil.
Yum! Ripe tomatoes
It concerns me that you have been growing tomato plants in the same
place for a number of years. Growing the same crop in the same place
year after year does deplete the soil of crop-specific nutrients. It
also creates an opportunity for soilborne diseases to become
established in your garden. In the case of tomatoes, fusarium wilt
and verticillium wilt are of most concern. Even in a small garden,
crop rotation is an important tool to minimize the chance of such
diseases becoming established in the soil.
Remember that it is
important to rotate among vegetable families, rather than specific
crops. For example, it would not be helpful to rotate between
tomatoes and peppers, eggplants or potatoes because they all belong
to the nightshade (Solanaceae) family.
Below is a chart to help you plan crop rotations: