Liming myths and questions

11 years ago

I got a soil test report back and it recommends the common very-high application rate of lime, 50-100 lbs / 1000 sq ft.

I have been researching how much and what type of lime I should be applying, and have run across some conflicting information that I wanted to discuss here.

1. I have read things like: "Calcitic lime is actually cheaper than dolomite when you factor in its effectiveness. Less calcitic lime has to be applied than dolomite to get the same result".

This doesn't make sense to me. Per the below two links, dolomite lime actually has a HIGHER CCE than calcitic lime due to the lower atomic weight of Mg compared to Ca. So, ignoring the fact that dolomite lime will also raise your Mg levels, it doesn't make sense to me when people say that calcitic lime can be applied at a lower rate than dolomite to get the same results. Thoughts?

http://pubs.ext.vt.edu/452/452-510/452-510.html

http://www.cals.uidaho.edu/edcomm/pdf/CIS/CIS0787.pdf

2. I have read things like: "The 50-100 lbs / 1000 sq ft recommendations from soil test reports are for "cheap" dolomite lime. You never want to apply that much calcitic lime at once. Calcitic lime should only be applied at a max of 9-10 lbs / 1000 sq ft at one time."

Due to dolomite lime having a higher CCE than calcitic, this also doesn't make sense to me. If it's okay to apply 50 lbs of dolomite at once, why is it not okay to apply that much calcitic at once? Where does the maximum 9-10 lbs of calcitic lime recommendation come from that I've read here on this forum? Is it because the actual calcium carbonate content of calcitic lime is higher than that of dolomite? Why does this matter, even though the CCE is actually lower in calcitic vs. dolomite?

I studied the label up and down for Pennington's "fast acting" lime, which is a calcitic lime, and it doesn't mention anything about a maximum application rate. It does provide "recommended" rates based on your current pH, and the highest rate in this list of recommendations is 24 lbs / 1000 sq ft.

Any thoughts would be appreciated.

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Comments (2)

goren
11 years ago
I wont go into specific types of lime you evidently have researched but it seems to me if you trust the laboratory that did your soil test, and it advised giving your lawn 50 lbs per 1000 sq ft. then I would suggest, if you don't believe this to be what is best for your lawn, then get another test done by another lab.

It does seem high...with all the recommendations far less than that and applications should be done 2 - 3 months apart...half now, half later. This cuts down the chance of major damage being done over a wide area if your pH should suddenly shoot up.
It takes time for lime to work its way through the soil so the time interval enables you to see what small improvements (if any) might be seen.

Liming a lawn any time is generally accepted as a good rule to follow. Increased use of nitrogen based fertilizers can have an effect on the soil's pH --toward the acidic--while lawns do well by having a pH in the neutral range...6.8 - 7.2.
Where one has multiple plants that prefer an acid soil---rhodos, azalea, etc....if one treats the soil that is close to lawns to help the plant, without due regard for the lawn, one can inadvertently lower the soil's pH.
Hand fertilizing on lawn areas is, for this reason, a good rule.

pH should never be taken in one area and accepted as what it is for the whole area. A compromise must be allowed.
For this reason, soil samples are taken in widespread areas of a property.
gardenbear1
11 years ago
I would first ask at your local garden center not a big box store about using lime and how much they recommend, when I moved into my home 9 years ago the front lawn was a mess I knew it needed to be limed, so I had a test done was was told 50-100lbs per 1000 sq ft.I check with the garden center and was told to use 25 lbs per 1000 sq ft.and now my lawn is doing great I lime every other year with the same amount. I think a local garden center would help a lot they should know your area
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