LIMESTONE - THE BASICS




The soil pH is a critical measure of how efficiently your camellias will absorb nutrients from the soil. Many expert growers think that the optimum pH for camellias is around 6.5 - just slightly acidic. In many areas of the "Camellia Belt" the pH is often in the 4 - 5 range - much too low.

Nutrient Availability
Nutrient Availability by Soil pH Level

To remedy this problem people have usually applied limestone (calcium carbonate - CaCO3) to their camellia beds. There are two commonly used types of limestone available:
In many coastal regions the soil tends to be sandy and has little magnesium content. It is better to use the Dolomitic Limestone in these areas.  Usually Limestone comes in 40 pound sacks which should cost $4 - $5 per bag. Limestone comes in two forms:
The pulverized limestone gets into the soil more rapidly than the pelletized, but is very dusty.

There are many ways to spread the limestone on your beds.  It can be done with a fertilizer spreader or you can just "Sling it". The pulverized limestone tends to clog up inside spreaders which requires that you unclog it from time to time.

Limestone can be applied at any time of the year.

Manufactures suggest that you never apply limestone at a rate greater than 50 Lbs. / 1000 ft2 at one time. If you require more than 50 Lbs / 1000 ft2 to obtain your desired pH, it is suggested that you wait at least two weeks between applications. It is also suggested that you immediately water it in when you apply limestone. This yields faster absorption into the soil and also cuts down on limestone dust, especially for the pulverized version.

GETTING YOU SOIL TESTED

As an example of soil testing, I have used North Carolina. The State of North Carolina will test your soil for pH levels as well as a host of other things for free. All that you need to do is go to the County Cooperative Extension and pick up the sample boxes and instructions. The instructions tell you how to take soil samples. Once you have taken the samples and filled out the simple paperwork, just take them back to the County Cooperative Extension and that's it

Depending upon the time of the year, it can take anywhere from a couple of weeks to 2 months to get the results back - winter is fast & spring is slow.  You can check to see if your results are ready by going online at NCDA&CS Agronomic Division PALS Web Application.  Just type in your Last Name and click on "Search" to see if your results are ready.  Results can then be downloaded.  For the purposes of this discussion, you should look for the pH levels (7th item from the left) for each of your samples - see below.

Click on Report to Expand

Soil test Report
North Carolina Soil Test Report - Sample

Most of the other states in the "Camellia Belt" have comparable services. You can go to the below websites and see what you need to do in your state and what fees you will have to pay.

ATLANTIC COAST
GULF COAST
PACIFIC COAST
ESTIMATING LIMESTONE APPLICATION RATES

The problem now is to estimate how much limestone to apply to your camellia beds.  For camellia applications. there are two parameters that are important:
Limestone Manufactures have published guidelines for both of these parameters that you will often find on the limestone package:

Lbs. of Lime Needed per 1,000 sq. ft. to Raise Soil pH to 6.5
Current Soil PH Sand Loam Clay
4.0 100 175 230
4.5 80 150 200
5.0 65 110 150
5.5 45 75 100
6.0 20 35 50

To facilitate the calculation of your limestone needs, a Limestone Application Calculator has been developed. It incorporates the above tabular information as well as information about your camellia beds to calculate how much limestone you need to apply to each bed and how much overall limestone you need to purchase.

It is suggested that you open up the Limestone Application Calculator to understand the following.

The Limestone Application Calculator Excel Workbook contains two Spreadsheets:
The second spreadsheet, pH vs Application Rate, is just the data from the above table.  The purpose of the first Spreadsheet, Limestone Requirement, is to help you calculate your limestone needs.

The Limestone Requirement Spreadsheet is set up to allow you to have up to 10 soil samples.  The input and output is color coded as follows:
Input data are in Columns B, C, D, F & G. Column B is just a description of your camellia bed. If no information is input in a cell in Column B, no calculation is performed for that area.  Column C & D are used to calculate the area. If your area is not rectangular, use these two parameters to estimate your area - This is not rocket science. Column F is the type of soil you have. You must choose 1, 2 or 3.

The input data in Column G are the pH levels from your soil test.  Values of pH MUST be between 4 and 6.

Column E data are the "Effective" area of each camellia bed.  Column H data are the interpolated values from the above table for a given pH and soil type and Column I data are the total application weights in pounds for each area.

When the application rate exceeds 50 Lbs / 1000 ft2 the applications are broken up into as many as four additional applications - Columns J through M.

Cell C13 tells you how much total limestone to purchase - in this case 989.51 Lbs. or about 25 bags.

Now comes the hard and dusty part.  Don't forget to water things in!