Thursday, March 15, 2018

Soil Testing: CSU Extension or DIY?

Photo by Donna Duffy

One of the first recommendations that we make as master gardeners is to have your soil tested before you add any amendments, plant anything or take any action at all in your home garden. This is probably the most important step any gardener can take before planting that first seed. The "blue chip" soil test is done at a Cooperative Extension soil testing lab such as the one at CSU.

However, we know that realistically, many home gardeners utilize a "do it yourself" soil testing product from their local garden centers.

So how do those testing kits stand up against the "real deal" at the Soil, Water and Plant Testing Laboratory at CSU? 
Maximum Yield Magazine has an article about which soil testing method gives the gardener the best results.  Here's the bottom line:

Do it Yourself Soil Testing:
  1. Lots of choices: Kits that  tell just pH; others  for individual nutrient levels, and comprehensive tests to do it all . There is usually a kit out there that can match your needs.
  2. Inexpensive:. There are dozens of types, ranging from a few dollars for an easy, disposable kit to more expensive, more precise kits.
  3. Fast Results: The results of a DIY soil test can become evident in minutes. 
  1. Accuracy: Most DIY soil kits do not offer the precision of a lab test. Many only give pH range instead of the actual pH.
  2. Contamination Risk: Even when following instructions carefully, there is a greater risk of contamination when testing at home versus in a controlled lab condition.
Cooperative Extension Soil Testing
  1. Reliable Results: Tests are performed by employees of the extension service or lab, so the samples are properly handled, processed, and that the results are accurate.
  2. Thoroughness: Soil samples will reveal the presence or absence of many more nutrients than most DIY kits. 
  3. Analysis: Lab analysis will tell what is in soil, and prescribe a course of action for what is needed. It will give exactly how many pounds of each nutrient or amendment should be added tand recommend other cultural practices to help growers achieve their growing goals.
  1. Cost: While not likely to break the bank, growers will generally pay two to three times more for a lab analysis of their soil through a cooperative extension service than if they were to perform the test themselves.
  2. Waiting for Results: If growers need answers right away because they have high-value crops starting to fail, a lab analysis may not yield the results they need in the time frame required to take action and reverse the problem. Samples generally get analyzed in the order they were received and can be held up by weekends, holidays, employee shortages, etc.

Whatever you decide, take time to test your soil before planting or making amendments.