The latest hot topic among gardeners these days, deals with the important relationships that plants have with microscopic organisms. Unless you have some pretty sophisticated equipment for viewing these creatures, you may never actually see one outside a picture in a book or a prepared slide at a seminar. Although fascinating as it is to peer into the hidden world of microbes, it is not important that we know what various microbes look like. It is important that we understand them and how to maintain an environment that promotes their existence.
There are so many various fungi, bacteria, protozoa, nematodes, and tiny arthropods that we have just begun to identify some of the more beneficial microbes along with those that can be damaging. The bad microbes like root-knot nematodes and powdery mildew (a fungus) were the first to get our attention due to the damage to our plants that is easily seen. However, there are good fungi and bacteria as well as bad. Throughout Nature’s kingdom we see predator, prey, parasites, good guys, and bad guys. So it goes in the unseen world.
Although beneficial soil microbes were known over 100 years ago, they are just now becoming the main focus in soil science. Seems we should have studied the beneficials, along with the various disease organisms that were studied in depth during the 20th century. We’ve since found that these good guys actually protect our plants from the bad guys. The analogy I’ve heard that makes good sense to me is what I call the “parking lot theory.” If we pull into a parking lot and all the spaces are taken, we just have to find somewhere else to park. Besides simply crowding out the bad guys, there are also those predator species that seek and destroy disease organisms.
Other microbes feed our plants by converting free nitrogen from the air and making it water soluble. There are still more that break down minerals and organic matter. Even some whose function is to clean root and leaf surfaces to promote growth. These beneficial microbes can be found everywhere. On leaf surfaces, roots, inside of roots, in the soil around the root zone (rhizosphere), even inside of larger creatures like earthworms. All these beneficial microbes are symbiotic. In other words, they need the plants to create habitat, to feed, and reproduce. The plants in turn receive benefits from the microbes. In fact, the plants actually share sugars and carbs from chlorophyll by exuding some through their roots to keep these micro-organisms concentrated in the rhizosphere. I’ve heard it said that as much as 20% of chlorophyll production may be going to soil microbes instead of the plant itself. I’ve also read that certain plants are dependant upon mycorrhizae (fungi that live on and inside roots) and simply cannot live without them.
No matter if you are not interested in the individual names and function of these creatures it is sufficient just to know they are there for good reason and how to promote a good environment for them. Like all other creatures, microbes need food, water, air, and a hospitable place to exist. Adding compost or leaving organic matter to decompose is of extreme importance. Loosening tight soil is beneficial. Irrigation during dry spells will also help keep microbe populations healthy. You can also increase microbes by adding products like corn meal and/or molasses that contain natural sugars. Remember the sugar complex translates into energy for all organisms regardless of size.
If you have been using the organic approach to gardening all along then you can be certain that you have plenty of the beneficial organisms in your soil. Likewise if you see earthworms, pill bugs, and other visible soil dwellers. On the other hand, if you have been using synthetic fertilizers, herbicides, or poison for insect control, chances are you have no earthworms and that means you’ll find very little microscopic life as well. When we work with Nature, we reap the reward. When we attempt to control Nature, we pay the consequence sooner or later.
While we are on the subject, I hope some soil scientists are studying the effect that chlorinated water has on these tiny creatures. I have yet to hear of anything published on the subject. I suspect that since we put chlorine in our drinking water to kill certain organisms that could make us sick, it will also have a negative effect if not cause the immediate destruction of many soil dwellers. Chlorine is poisonous. Poison is not conducive to life in general. At any rate, it does make a good case for harvesting rainwater or using some other freshwater source as much as you can for irrigation.
Another habit we humans have that is destructive to soil life is constant tillage. Vegetable gardeners know that tilling the soil on sunny days will kill destructive nematodes. It will also kill beneficial nematodes as well as a host of other critters that are not built to take direct sunlight. The underground world is one of shadow and darkness. ”No Till” agriculture is catching on and the benefits are becoming obvious. You and I as home gardeners should follow suit. Don’t disturb the soil any more than you have to. Let Mother Nature do the work.
On the bright side these things we can’t see do have the ability to establish themselves at an astonishing rate. Most of you have seen that bacteria can reproduce quickly in a compost pile. So much energy (heat) accumulates as these guys expand, reproduce, and expand again that there have been documented cases of fire starting. All of us have had viruses that can go from sniffles and mild discomfort to full blown colds or flu in less than 24 hours. Such is the nature of microscopic life given ideal conditions.
At our nursery we have been selling packaged fungi and bacteria for years. One three ounce package can inoculate a hole big enough for a 15 to 20 gallon tree. In addition, these beneficial fungi and bacteria will increase and stay with that tree for its entire life. Miracles do exist in Nature. No fertilizer or root stimulator ever gave us this kind of longevity
Since the introduction of synthesized fertilizers after World War II, we have moved from “feeding plants” to “feeding the soil.” Now we are beginning to understand that we actually have been feeding microbes all along and it is their job to feed the plants. Once again, organic gardeners have been doing the right thing all along. Our soil science is just now catching up to us. Now we are better able to understand how and why this works. The evidence is compelling to say the least.
One of the most exciting things that have come lately is aerating tea brewed from compost and other natural water soluble products. Remember that all living things must breathe. It seems that adding air to water has much the same effect as turning a compost pile. Most of the true cutting edge organic gardeners are either brewing their own tea or buying a commercially brewed product.
Make your own tea by making a “tea bag” from an old onion sack or any material with fairly large mesh construction. Put your compost inside this and immerse in water (non-chlorinated, please). Any container will work but most home gardeners find a 5 gallon bucket just right. Next add a simple aquarium pump with an air stone attached and let this brew for a minimum of 24 hours or more and you have your basic aerated compost tea.
Commercial brewers all have their favorite recipes. The one common thread among these is diversity. The more diverse your various components are cause greater diversity among your beneficial microbes. We like to use stuff like molasses, liquid hamates, sea weed, and fish emulsion in ours. Any water soluble natural product (left over tea, fruit juice, or even beer for example) will add to the microbe count.
Most important is to use aerated compost tea while it is still “hot.” Apparently the microbe count begins to decrease shortly after the extra air or agitation is stopped. Coat all the leaf surfaces concentrating on the undersides plus stems and the ground around your plants. Results will speak for themselves. Less insect attacks, little or no leaf fungi, and a healthier, more productive plant.