A customer recently called to ask if his side-dressings of 10-10-10 on vegetable plants was OK. Guess it's time to revisit the subject of fertilizer compatibility with soil organisms.
First, our basic recommendation is to avoid synthetic fertilizers when using biological growing methods, especially immediate-acting liquids. At best, the non-organic "plant food" disrupts the normal biological activity that provides nourishment and protection to plant roots. At worst, repeated applications kill off the valuable organisms in the soil, leaving plants entirely dependent on human inputs.
Also, 10-10-10 or 20-20-20 neither "balanced" nor "complete" - regardless of what the chemical industry says about such fertilizers. For full health, plants require more than a dozen additional minor and trace elements beyond NPK. This is not just theory or speculation. The word "essential" has a definite meaning for these added nutrients.
I was told by a mycology scientist at the USDA's Horticultural Research Laboratory that he had experimented with an 18-6-12 slowest-release form of Osmocote-type fertilizer that did not seem to damage mycorrhizal fungi, but applied it at only half the recommended dosage. He said that stronger dosages were harmful. And of course, many of the elements essential to full plant nutrition are not included.
It must be recognized that big corporate farm operations would have substantial problems adapting to biological methods after relying on chemical fertilizers for decades. It would take considerable time and expense to rebuild populations of beneficial microorganisms in the thousands of acres that have been made basically lifeless. Realistically, as long as such soils can continue to produce yields by using convenient NPK synthetics, there will be little motivation to change methods. Whether such practices are sustainable for much longer is the issue for debate.
But there is really no reason for home gardeners, landscapers, or small market growers to use big-farm methods. We have found that plants grow wonderfully well when given very small amounts of dry organic fertilizer, broad-spectrum volcanic minerals, and the introduction of specific mycorrhizal fungi to their root systems.
A typical organic fertilizer might have analysis numbers like 5-1-3 or 9-3-5. A good mail-order source is Peaceful Valley Farm & Garden Supply - see www.groworganic.com They also have a printed catalog with a wealth of growing advice.
Just keep those analysis numbers low and the release slow. You'll see some very happy plants if their companion soil organisms are happy.
Good growing, my friends,
Don Chapman
President, BioOrganics, Inc.