Agriculture Reference
In-Depth Information
Back to the numbers. Again, these ideal percentages vary depending on who you ask
and on testing procedures the lab is using. On sandy soil, calcium goes down closer to
60%, magnesium up to 10-20% and potassium potentially up to 6-8%. This is because the
magnesium and potassium help the sandy soil to bind together. It may be that the numbers
are different for some trees and ornamental plants, but I've never seen this data anywhere,
so I've always applied them to all plants. They certainly work for various kinds of foods
all over the world, from corn to bananas to other fruit trees to coffee.
It's very important to note that the amount of each nutrient in your soil is not as import-
ant as having the correct percentages. In fact, a lack of nutrients is not the problem in our
soils. The nutrients are there. The problems are that they are out of balance and the soil
food web is not healthy and diverse enough to extract what is there. If you were to take a
soil sample from a healthy forest, a soil lab would probably tell you that soil was very low
in nutrients. What the forest has is a highly functional soil food web to keep the nutrients
recycling in the system. It certainly doesn't have anyone adding fertilizers.
Getting the soil food web working in our own soil is one of the most important goals on
which we need to focus. And we don't need to add much in the way of fertilizers, but cor-
recting the nutrient ratios is important to create an environment in which microbes and
plants can flourish. We need to work on the biology and the nutrients at the same time.
Here's a summary of the ideal soil nutrient percentages:
