Question
I was wondering if I could use fresh water mussel shells as a fertilizer if I crush them up?  If not a fertilizer, then would they have any benefit in the home garden?  I grow tomatoes, herbs, and blueberries.  Any help would be great.  Thanks

Answer
University of Maine's Agricultural and Forest Analytical Lab posts their Mussel Shells analysis at its website.  They note:  'The shells are quite pure, with a Calcium Carbonate equivalence of 95 to 100 percent.  When crushed to sand size, shells make an excellent Lime...Mollusk shells are almost entirely CaCO3' -- Calcitic Lime -- 'with very little MgCO3' -- Magnesium Lime.  You can read the entire report, which is packed with pH and other data on Poultry Manure, Wood Ash and Waste Lime, here:

http://anlab.umesci.maine.edu/handbk/recomend.HTM

They post plenty of Blueberry growing advice in their report, 'Growing Blueberries in the Home Garden':

http://www.ces.ncsu.edu/depts/hort/hil/hil-8207.html

These terms may be unfamiliar to you.  The short answer to your question is, Yes, crushed Mussel Shells are an EXCELLENT Soil amendment IF your Soil needs it.  In this case, you need a Soil that will support growth of specific crops, including Blueberries.

You probably realize Blueberries have a rather extreme pH requirement.  North Carolina State University School of Agriculture points out, 'Blueberries require a lower pH than many other small fruit crops.'  NC figures you should shoot for a pH of around 4.8 for Blueberry plants to fluorish.  Two authorities on growing Blueberries, Wei Yang and Bernadine Strik, are somewhat broader in their website on 'Organic Blueberries', set up for the Northwest Berry and Grape Information Net, a project of Oregon State University, University of Idaho, Washington State University and the USDA.  Drs Yang and Strik will advise you, 'Blueberry plants grow best at a soil pH between 4.5 and 5.5.  The low pH requirement of Blueberry plants is essential for the uptake of nutrients.'

Now let's look at Tomatoes.  In a short piece, 'Perfect Soil for Growing Great Tomatoes', at the website GardenPlantCare.com, they point out, 'Tomatoes will grow within a Soil pH range of 5.8 to 7.'  Here's the URL:

http://gardenplantcare.com/Vegetables_21/soil_improvement_tips_tomatoes.shtml

Soil with an Acid pH is necessary because the Tomatoes themselves are very high-Acid fruit.  Acidity varies somewhat by hybrid.  NDSU's Extension Service gives the public pH information on individual Tomatoes to help people can and preserve Tomatoes they grow at home safely -- certain dangerous bacteria cannot contaminate food at a pH 4.6 or lower.  So NDSU tell us that the Russian Tomato has a pH of 5.09; Bush Celebrity, a pH of 4.93.  Go here to see their list:

http://www.ext.nodak.edu/food/lemnjuic.pdf

Herbs, in contrast, as a group do best in Alkaline soil. Mussel Shells may be appropriate, but the only way to know is to get a Soil Test.  Not a do-it-yourself quickie, but a world class study by scientists who can break down the composition of your Soil and calculate precisely what you need to make it perfect.  You need to know the pH of your Soil and you need to know asap whether Mussel Shells can be helpful or harmful to things you want to grow next Summer.  Send me your zipcode, and I'll give you the contact info for your local cooperative extension or other soil test service.  The price is less than a tank of gas.