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How much does each amendment weigh?

Jeremy Silva |

I'm often asked how much each one of our soil amendments weigh. 


Here is a short post to help, rounded to nearest half ounce.


1lb = 16oz

1 Cup = 16 Tablespoons

1 Cubic Foot is equal to about 7.5 gallons of soil.

1/2 Cup Per Cubic Foot = about 1 Tablespoon per gallon.

Most amendments are recommended to be used with 1/2 Cup Per Cubic Foot of Soil and that Works out to about 1 Tablespoon Per Gallon of Soil.

Amendment Name:

Weight In Ounces Per Cup:

Fish Bone Meal   8 Ounces 
Crustacean Meal 7 Ounces
Kelp Meal 7.5 Ounces
Neem Cake 6.5 Ounces
Alfalfa Meal 2 Ounces
Oyster Flour 8 Ounces
Gypsum 9 Ounces
Soft Rock Phosphate 9 Ounces

Glacial Rock Dust

9 Ounces

Barley Seed

6 Ounces

Worm Castings

7 Ounces



Anything else I should weigh?


I meant 8 cups per pound not gallon.

Nick W,

I see u have alfalfa meal at 2oz per cup but that would be 8 cups per gallon…..your alfalfa meal says 10# bag is 39 cups? Can you clarify this for me? Thanks!

Nick W,

It might be helpful to have conversions in both directions by saying how many cups are in one pound. Something along these lines: “there is about 2 cups in one pound of fish bone meal”. It is a bit redundant, but for those people who are bad at math, it could simplify things a bit.


Thanks for the question Nick! I Just updated the blog to reflect the weight. EWC are about 7 pounds per gallon.


An average weight per cf maybe of your worm castings? However would be easiest :)


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