Agriculture Reference
In-Depth Information
Nutrient Access Versus Nutrient Quantity
There has been some research, such as that done by Brazilian soil scientist Ana
Primavesi and put to the test by Roland Bunch, showing that it's important for plants and
microbes to have consistent access to a small amount of many different nutrients. In fact,
that is much more important than sporadic access to a large amount of nutrients — as is the
case when we pile on chemical fertilizers, or even mineral fertilizers, at one time.
Ana Primavesi did an interesting experiment. This was done with hydroponics, and it's
just one experiment, but the principles still apply. She had four test plots. A regular solution
was given to plot 1 every four days. Twice as much was given to plot 2 every four days.
1/50
th
of the regular solution was given to plot 3 every four days, and 1/50
th
of the solution
was given to plot 4 every
two
days. So the first 3 plots were fertilized every four days,
while the 4th plot was fertilized every two days.
Plot 2, with twice the nutrients, did not grow as well, indicating more is not always bet-
ter. Plot 3 also did not grow as well, so less is not always better. Where it gets very interest-
ing is in plot 4, which grew slightly better than plot 1, presumably because plants had more
consistent access to the nutrients, even though it was at 1/50
th
the amount.
So consistent access to a small amount of nutrients was more important than access to a
large amount of nutrients all at once. This is also what organic matter does for us in soil. It
holds onto nutrients and is composed of nutrients. Through the breakdown process, these
nutrients slowly and consistently become available to plants, frequently and a little at a
time.
Ana Primavesi, Elaine Ingham and thousands of people around the world have con-
firmed that plant health is improved when the soil food web is improved, one of the main
reasons being that microbes make nutrients more available to plants. One simple experi-
ment from Elaine Ingham illustrates this. Grasses grown in sterile media didn't do as well
as grasses grown with one species of bacteria, which in turn didn't do as well as the plots
where one species of bacterial-feeding nematodes were added with the bacteria. When the
nematodes eat the bacteria, nutrients are available that can be used by the plants.
