Testing Your Soil: Why and How
Why have your soil tested?
Applying the wrong kinds of fertilizer can harm your crops and be a costly waste of money. It can also affect our coastal waters and drinking water by washing into streams or leaching into groundwater. Also, failing to correct soil problems or apply enough of the right types of fertilizer to your crops can result in poor yields and wasted effort.
Have your soil tested:
- To find out if there are unseen problems
- To find out if you should add fertilizer
- To find out what kind of fertilizer you should use
- To find out how much fertilizer you should apply
Basic Soil Analysis provides information about the pH of the soil, which tells you how acidic or alkaline your soil is, and about the available nutrient levels in the soil.
Specialized Soil Analysis can provide information on soil salinity, Nitrogen levels, organic Carbon levels, and micronutrient levels. You can also request testing for Aluminum levels or the presence of heavy metal contamination. Finally, you can test the particle size distribution which indicates the proportion of sand, silt and clay particles in your soil.
How do I Take a Soil Sample?
Please note, Komohana no longer takes soil samples.
For complete directions, consult the CTAHR publication “Testing Your Soil: Why and How to Take a Soil-Test Sample” at the following link:
https://cms.ctahr.hawaii.edu/Portals/43/AS-4.pdf
- Bring in 2 cups of soil in a zip lock bag
- If you have different soil types in different areas, bring in separate samples
- Bring a sample from the top 4 inches for lawn, from the top 8 inches for tilled fields or garden plots, and two separate samples of the top 8 inches AND the 8 inch to 24 inch zone for tree crops.
Where can I get my Soil tested?
While UH CTAHR cannot recommend specific products
or services and does not guarantee these services, there
are common labs that customers and faculty have relied
on and partnered with, in the past and currently. These
include:
• Crop Nutrient Solutions, HI (www.cropnutrientsolutions.
com)
• Laboratories on the U.S. Mainland (naptprogram.org/
about/participants/all) that participate in the North
American Proficiency Testing (NAPT) Program (www.
naptprogram.org).
• Another useful source of general information on certified
labs is the Agricultural Laboratory Testing Association
(ALTA) (alta.ag/certified-labs)
• Please note, if you live on:
o O‘ahu: Crop Nutrient Solutions has permits to accept
your soil test.
o Maui: Crop Nutrient Solutions has permits to accept
your soil test.
o Kaua‘i: Crop Nutrient Solutions has permits to accept
your soil test.
o Moloka‘i: Please contact a NAPT lab to confirm it has
permits to accept your soil test.
o Hawai‘i Island: Hawai‘i County does not allow soil to
be sent to another Hawai‘i island. Please contact a
NAPT lab directly.
Agricultural Diagnostic Service Center
• Once you receive test results, please contact your
Extension agent, who can assist in interpreting those
results and providing science-based recommendations.