Agriculture Reference
In-Depth Information
Calcitic Lime (30% Calcium and 4%
Magnesium — Varies)
Calcitic lime, also known as high-calcium lime or calcium carbonate — or aragonite,
which is actually ground sea shells — is the main rock fertilizer used to increase calcium
levels, especially when the base saturation test is low. As mentioned, some people are mov-
ing to liquid calcium as the first choice, but be forewarned it's not always able to bring cal-
cium levels up high enough.
Calcitic lime is not to be confused with hydrated lime or quick lime, which aren't ap-
proved in organic gardening standards. They can be beneficial, but they can burn crops, as
well as your skin. Calcitic lime contains approximately 25-35% calcium and a few percent-
age points of magnesium. Some soil labs may recommend 45 pounds per 1,000 square feet,
while some soil scientists like Dr. Arden Andersen, author of
Science in Agriculture,
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vocate starting out by using less, such as 10 pounds, perhaps applied more often.
Neal Kinsey of Kinsey Agricultural Services recommends calcitic lime as high as 180
pounds. Personally, I stick to the lower end of the scale because every time we add any fer-
tilizer, we impact the soil environment and the soil food web. As I've already mentioned, I
prefer to use fertilizers slowly and work on the soil food web for further stimulating fertil-
ity.
I'll use 10-45 pounds per 1,000 square feet in my garden in one year, and some people
would advocate even less. Actually, I follow both of these pieces of advice by keeping the
application rates low and spreading them out during the course of the year. I apply 10
pounds per 1,000 square feet, as often as twice in the spring about four weeks apart and
twice in the fall.
There's one circumstance in which I may apply calcitic lime without a soil test — when I
see an explosion of weeds that indicate a calcium deficiency, such as dandelions and crab-
grass. I'd almost always take a soil test anyway. In North America, calcitic lime should be
between $7 and $20 for a 50 pound bag, so it's definitely not too expensive for a typical
residential garden. The price depends whether you buy it from a wholesale farm supplier or
from a retailer, as follows the range of the other prices in the next few chapters.
Sometimes, the base saturation is okay, but the Reams test is low. This means we may
have sufficient calcium in the soil, but our plants just can't get enough of it. We may still
add some calcitic lime, but there are probably more important things to do. Why isn't that
calcium available? Perhaps we need to throw a bit of a party for our microbes to coax them
to get excited about getting to work on the calcium. Liquid calcium is often used for this.
Also, aerobic microbes need sufficient air in the soil and the right amount of moisture.
They like humic acids, compost and leaves. They like sugar, especially molasses. So, the
easiest first steps are to make sure you're irrigating properly and adding enough organic
