Agriculture Reference
In-Depth Information
Next we can easily determine our base saturation deficit. If we're trying to get a calci-
um base saturation of 68%, which is often considered ideal with a proper Albrecht test,
and if our current base saturation of calcium from the above soil test is 37%, then our de-
ficit is 31% (68-37=31). You can see that the bigger the deficit, the more fertilizer you'll
need to add.
Last, we need to know how much of the required nutrient is in the raw material we'll be
using. Let's say in this case that we're using calcitic lime as our calcium source, with a
calcium content of 35%. If it was only 25% calcium, we would have to use more of it.
Plugging the numbers back into the equation looks like this:
7.7 x 400 x 0.37 / 0.35 = 3,256 pounds per acre
The soil lab will probably round down to 3,000 pounds per acre, so approximately 70
pounds per 1,000 square feet. That's how much calcitic lime we theoretically need to add
to bring the calcium level up to 68%. Of course, there is margin for error in all parts of the
equation, so it's not exact. Also, the soil is highly complex and certainly does not repres-
ent perfect lab conditions, so things will definitely work out differently than we plan, but
this is a good start.
I would split this into four applications throughout the year, which works out to 17
pounds each application. Personally, I would bring it down to 10 pounds per application.
The more I learn, the more I feel we should make fertility changes slowly and see if we
can partially improve soil fertility levels by also improving the health of the soil food
web.
This calcitic lime is going to supply perhaps 4% magnesium, so that should be taken in-
to account, too. Don't worry if these numbers are a bit much. As you can see, this can get
rather complicated, so you can just let the soil lab do it for you. They can also factor in the
Reams test and other wisdom. I wanted to show you how to do it so you can understand
the factors that affect fertilizer recommendations.
