Agriculture Reference
In-Depth Information
Cooperation and Competition
All of these members of the soil food web exist in the same space. They work together
and they also compete. They fight wars for land and food and water, and they join together
to produce these same things. There is competition, but there is also cooperation. None of
this is bad — it's just nature. It's all good. As gardeners, we are thrilled by this cooperation
because it allows us to garden, to grow healthy food and beautiful flowers.
The cooperation between plants and microorganisms is fascinating. The microbes bring
food and water to plants in exchange for other food that is made by the plants. This is the
original bartering system. Plants can send well over 50% of the carbohydrates and thou-
sands of other substances they make during photosynthesis into the soil as exudates (food)
for microbes. The microbes give plants the food they need in return, as well as protection
from predators. These exudates are one important method plants use to build soil.
Perhaps the most popular example of cooperation is between plants and pollinators —
mainly insects and birds. Plants custom-make food specifically for their pollinators, who
come and get the food. In the process of moving from flower to flower, they pollinate the
plants.
One of the most interesting examples of cooperation in the soil is nitrogen-fixing bacter-
ia, many of which live in little homes right on the roots of certain plants, mostly legumes
like clover and peas. These bacteria take the nitrogen out of the air and change it into a
form the plants can use. Plants can't do this, but they can get carbon out of the air —
something the bacteria need. Thus begins the trading that allows all other life on earth to
exist.
Certain species of microbes colonize the leaf surface, contracted to defend the leaves
against predators and pollution. If they aren't there, the plants won't last long. Many other
species set up shop in the rhizosphere, the area right around roots where much bartering
takes place. Plants send out certain foods to attract the specific microbes they need at any
given time.
There are endless relationships like this. It's important for us to realize that we need all
of these players in our garden in abundance. We need a lot of them and we need a diverse
group. Just like we don't want to plant monocultures, we don't want bacterial monocul-
tures, or fungal or animal monocultures, either.
In fact, if we only have a few of the 30 or so functional groups of microorganisms
(groups that have similar functions, such as nitrogen fixing, decomposing, or photosynthes-
izing), then our garden will gravitate toward becoming a desert. We can artificially keep it
alive for quite a while, but we will also see the system get more and more sick — as we are
seeing right now all over the planet. We will have more and more plant predator problems,
