As the use of biological methods for crop production and landscaping gains wider popularity, it seems some people view it as a some sort of rival to soil chemistry, which has dominated agriculture for several decades. To me, this is the wrong way to look at the issue. This need not be a contest between two different approaches to growing plants - it’s not biology looking to wipe out chemistry (or as some seem to see it, good versus evil). An intelligent perspective would be to blend together elements of both sciences in a way that provides the maximum benefits to plants in a sustainable, non-polluting manner.
A plant in biologically-active soil has many advantages. It is more resistant to diseases, insects, soil pathogens, and drought because of superior nutrient uptake and natural defense mechanisms that come from association with mycorrhizal fungi. Therefore, it is a given that growers should introduce and encourage large populations of beneficial microorganisms.
As these beneficial soil microorganisms can be easily damaged or destroyed by strong fertilizers, a basic guideline for bio-growers is to avoid all fast-acting, high-analysis “plant food”. The harm that such fertilizers cause to valuable soil bio-life far outweighs any short-term benefits.
The alarming contamination of underground drinking water and streams just adds a further reason to cut the use of cheap NPK fertilizer, including the vast tonnages of lawn food and water-soluble stuff being routinely overapplied by homeowners. Farmers aren’t the only offenders in this category.
Many growers also seem to have become nitrogen junkies - thinking that N is the solution to any and all plant problems. True, one can usually produce a quick greening effect by applying nitrogen. But in truth, it is no more important than any other element to the overall health of a plant. A broad range of elements are needed, all in differing amounts (just as for humans).
In nature, this is one of the most important roles of mycorrhizal fungi - to seek out nutrients in the soil for their host plants and to regulate the amounts of the various elements. You could think of the fungi as being responsive to the needs of their companion plants, and for good reason. The fungi are entirely dependent on the symbiotic relationship with the plant for their own survival. Without root exudates, the fungi die (leaving behind spores which will only activate when a new root comes nearby).
This leads to the point that soil chemistry cannot be totally ignored, although under a biologically-oriented program the standard NPK chemistry is not all-important. The soil biota will perform corrections to pH, generate N from the atmosphere and solubilize other soil elements - functions that chemistry-oriented growers try to duplicate with varying degrees of success.
The goal of the bio-grower is to ensure that the widest possible spectrum of minor and trace elements are available to the foraging fungi, while providing much-reduced amounts of NPK in gradual-release forms. If tiny amounts of boron or selenium or any other essential minor/trace element are absent from the soil, then the fungi cannot find it and plants cannot enjoy full health. This is the appropriate chemistry side of the equation: to provide every possible chemical element to the soil-searching fungi so that they can bring them as-needed to the plants. Note that it is not necessary to provide all elements in ideal ratios to each other; the fungi will make the appropriate uptake adjustments. Of course, extreme overdoses of any element are to be avoided.
This is a different way to view soil chemistry - in a supportive role to the microbial populations - but the net effect is a powerful and non-polluting way to produce high-yielding crops and ornamentals. Simply put, the current overemphasis on NPK fertilizers needs to be redirected to include many more elements in small amounts.
The simplest way to ensure a broad range of elements is to occasionally apply volcanic-origin mineral powders or rock dust to the soil. However, be aware that not all rock dust contains the desired broad range of elements. The best I’ve found is called hydrothermally-changed Dacite. This is basically a soft volcanic rock deposit that has been steamed for millions of years and is now a crumbly form containing virtually every element. A commercial product called Zeolite is also good, as is greensand.
Getting the soil chemistry right is indeed important, but not the kind of blunt-instrument NPK chemistry that we have been practicing. Keep the soil organisms happy with a wide-range diet, and their host plants will also be happy.
Cheers, and good growing, friends.
Don Chapman
President, BioOrganics, Inc.