The more I learn about how soil and worms and fungi and bacteria and plants interact, and how their underground “systems” work, the more I realize how mistaken we are about so many things. Our intentions are good - we’re following prevailing soil chemistry advice given in textbooks, articles, and by crop advisors - but much of what we do for (or to) our plants and crops is horribly wrong.
To understand the problems, first consider the natural cycle of plant-soil-microbial relationships which have evolved over millions of years )greatly, greatly, simplified).
- Leaf litter, dead plants, bird and animal droppings fall to the ground.
- Decomposing fungi and bacteria “digest” the fallen material.
- Earthworms feed on the decomposed material and then transport it underground.
- Other types of fungi and bacteria feed on the earthworm castings, further digesting it.
- The bacteria produce nitrogen and digest minerals into forms plants can use.
- A plant seed sprouts or new root growth occurs in the biologically-active soil.
- Mycorrhizal fungi attach to the roots and send millions of root-threads out into the soil.
- The plant extends its leaves up into the sunlight, and performs photosynthesis.
- Mycorrhizal fungi and bacteria feed on root exudates generated by photosynthesis.
- In return, the fungi forages for whatever nutrients the plant requires for full health.
- The plant thrives above ground with these symbiotic actions going on underground.
- Leaves drop and/or annual plants die and we go back to Step #1.
The closer we can replicate the above cycle, the better our crops and plants perform. It’s difficult, and I would even say impossible, to improve on it. It seems that our goal should be to figure out how to work WITH the established method instead of trying to take over the complex soil functions ourselves.
But aren’t we helping the plants when we “feed” them? Well, not when we drench the soil with immediate-acting fertilizers, synthetic or organic. Small amounts of gradual-release broad-spectrum fertilizers and minerals can offset the leaf litter (crops) that we remove from the field, but whenever possible the crop residue should be allowed to remain in place.
Are we helping when we turn over the crop residue by plowing it under? Well, a no-till or limited-till program will keep the underground biological communities from being disrupted. A rototilling is the equivalent of a powerful hurricane leveling a human city. There are impressive results being reported from no-till agricultural studies and I expect many more farmers and gardeners will adopt this practice.
The “little soil bugs”, if encouraged to develop into large populations, will keep the soil fluffed-up for good aeration, will provide nutrients (in ideal proportions) for plants, and will protect the roots from pathogens. They will happily do all this work for free and will not contaminate our water supplies.
A side note on “Organic” additives: From my biological perspective, the “nature=good,” “manmade=bad” orientation is an imperfect way to judge materials. It does have the general benefit of prohibiting the most harmful fertilizers, such as high analysis fast-acting synthetics (i.e., 20-20-10) which can be lethal to mycorrhizal fungi, but it gives the impression that all natural materials are OK. In fact, a drench of liquid fish can disrupt the soil system far more than applying dry pelleted fish. A slow continuous supply of the broadest possible array of nutrients is the feeding objective for bio-growers.
For good reading on this subject, the March/April issue of The American Gardener (the magazine of the American Horticultural Society) has an article entitled “Fertile Ground.” One quote from a gardening writer: “I believe the biology of the soil creates the chemistry. It is only when the biology is killed off, as it is with salt-based fertilizers, pesticides, tilling, etc., that the chemistry takes over.” I say Amen!
The June issue of Mother Earth News will also have an excellent article on mycorrhizal fungi written by Doreen Howard, who has considerable first-hand knowledge of biological inoculants.
Both articles are geared toward home garden issues, but the overall descriptions of natural soil systems are certainly worthy of study by commercial growers, landscapers, plant researchers, and government officials concerned about agriculture and/or environmental issues.
Good growing, my friends,
Don Chapman
President, BioOrganics, Inc.