There are several types of soil tests that can be performed. Ideally all four tests listed below should be obtained.
1. Biological Soil Foodweb Analysis. This will show the ratios of the most critical beneficial and non-beneficial microbes in the soil: bacteria, fungi, protozoa, ciliates, nematodes, etc. The desired ratios of bacteria to fungi will also depend on the types of plants that will be grown at the site.
2. Soil analysis for nutrients and minerals. Not all soil tests are equal! Be sure to use a lab that can do a Base Saturation test, CEC (Cation Exchange Capacity), OM (Organic Matter content) and Reams testing for soil nutrients. This test most accurately measures the nutrients in the soil that the plants can actually utilize. It's a good idea to test for heavy metals as well.
Ask for fertilization recommendations based on an organic approach to soil and landscape management, including the amount of compost that would be required to bring the soil organic matter content to at least 5%.
3. Soil compaction tests. This can be done with a hand held soil penetrometer at several locations on the site to determine if there are areas where the soil has been compacted, what the compaction depth is, to determine if an area will need special remediation measures.
4. Percolation test for water drainage at several locations on the site. One location for every 80-100 square feet is recommended. Tree or shrub planting pits can be used for the drainage tests.
Based on the results of the soil tests a strategy can be mapped out. It is very helpful to consult a Soil Foodweb Advisor regarding the results of the Biological soil analysis and standard soil analysis. An approach can be formulated, taking all of the test results into consideration. If there are compaction or percolation issues these can also be addressed using a biological approach, since fungi are responsible for maintaining a healthy soil structure.
Some of the best tools we have for soil remediation are specially crafted liquid biological amendments such as Actively Aerated Compost Tea, or AACT. AACT creates conditions during brewing for microbes to multiply rapidly in the desired ratios. Once the existing levels of nutrients and biological activity are known and an approach outlined, AACT (make sure it has been properly balanced and tested, and continually aerated) can be applied to correct the biological balance in the soil.
When the tea is applied, the microbes continue multiplying, cycling nutrients in the soil and preventing disease from pathogenic organisms. Fungi continue growing, creating soil structure, improving the water holding capabilities of the soil, storing nutrients, etc. Properly brewed AACT must be tested (Soil Foodweb Analysis) and carefully monitored for the microbial balance before application. It cannot be off of continual active aeration for more than 4 hours before applying, or there is danger that it could start to go anaerobic.
Here are some great resources:
http://oregonfoodweb.com
www.soilsalive.com
elmscapes.com
www.treewiseorganics.com
Books:
Teaming With Microbes by Jeff Lowenfels and Wayne Lewis
Soil Biology Primer published by the Soil and Water Conservation Society
Post by Suzanne Schrift
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