There is some debate about how many elements are really, really, essential to good plant health. Growers with a chemistry orientation always focus on the macro elements - NPK - which are indeed needed in relative large amounts. Some more advanced chem-growers also pay attention to minor elements - calcium, iron, magnesium, etc. - which are needed in lesser amounts. Probably not one in ten thousand ever worries about trace elements, believing that they are either not as important or are hopefully in the soil already.
The critical need fortrace elements in a plant’s diet has been well documented, and their absence in some soils is probably the cause of many puzzling diseases and yield problems. A parallel situation is the human need for minute amounts of Iodine to prevent goiters - solved by making iodized salt.
The chemical grower faces a major problem in that all the essential elements - Macro, Minor, andtrace - must be kept in roughly correct proportions to each other. If the uptake of any essential element is too high or too low, the plant will suffer. Overdoses and deficiencies of individual elements are very common (perhaps even the norm) in chemically-amended soils - usually not to the point of killing the crops, but still preventing plants from performing at peak levels.
So how does a grower deal with a plant that needs twenty units of element A, ten units each of element B & C, two units each of elements D through G, and varying trace amounts of elements H-Z? How does one give crops ideal combinations throughout the life cycle of the plant? (This can get more complex, as the nutritional needs of plants change as they go from seedlings to maturity.)
The simple answer is that chemical growers find it impossible to measure, add, monitor, and regulate the uptake of all the essential Macro, Minor, and trace elements in ideal proportions. The best that can be done is to test for the major elements, conduct leaf analyses, and try to apply additives that will “correct deficiencies”. At one level, this does work, at least in the short run, but all too often the result is fields, orchards, or vineyards filled with imperfectly-nourished plants that invite disease and insects.
I think this is a key difference between chemical and biological methods. With chemistry as a base, there is little margin for error as far as proportions between elements and mistakes cause big problems with crops. Under biology-based methods, where bacteria process elements into plant-useful forms and mycorrhizal fungi regulate nutrient uptake according to the needs of their host plants, growers can have large variations in their soil elements and plants will still thrive.
For example, an excessive amount of boron in soil will not bother mycorrhizal plants because the regulating fungi will not allow the excess to enter the roots. This is also true for salts or heavy metals. Any amount of an element beyond what the plants require will be blocked by the mycorrhizal fungi. (Mycorrhizal inoculants are commonly used to establish plants in toxic mine tailings.)
The other side of the coin is that the foraging fungi cannot manufacture elements that are not in the soil, creating the need for growers to occasionally add broad-spectrum minerals (along with much-reduced amounts of fertilizer - perhaps only ten percent as much).
If there is “some of everything” present in the soil, then the fungi can pick and choose whatever their host plants need at any given moment in their development. The difference in health, vigor, and yields from perfectly-nourished plants can be dramatic.
It’s the grower’s choice: try to create the ideal recipe of all essential soil nutrients for the plants, or grow mycorrhizal plants that can adapt to just about any soil they find themselves in. Dealing with the uptake of plant nutrients is the beneficial fungi’s role in nature. They’ve been practicing the role now for many millions of years, and will be happy to take that difficult job away from humans if given the chance.
Cheers and good growing, my friends,
President, BioOrganics, Inc.