Conversion for planting

Question

I have this thing for chemistry and really would love some help.

Basically I have 120 ml plant cell and need to know how much soil to put in it. I intend to use the Dr. Earth Fertilizer (you can search it up on the internet) for my controlled herb group and it states: " FOR CONTAINERS: Use 1/2 cup per 1/2 cubic foot. (approx. 5 gallons) plotting soil.

Now I have converted my 120 ml (below is my work):

120 ml→120Cubic cm^3→7.32285inches^3→0.0042377cubic Ft

Looking at this it just seems like the number is too small. Can anyone help me with this.

Answer 1

1 ft³ = 28.3168 L

0.5 ft³ = 14.1584 L

14.1584 L = 14158.4 mL

0.5 C : 14158.4 mL :: x C : 120 mL

14158.4x = (0.5)(120)

Can you solve for x and answer? It's in cups.

Answer 2

Your calculation for the amount of soil in one plant container is absolutely correct. 120 mL is not a lot of volume; indeed, each is a little less than 0.5% of the volume of a cube with side length of 1 ft. It can be deceiving if you're looking at the soil within the container as the container takes up additional space; I am still in awe watching a fish tank receive 120 gallons of water after thinking only a few dozen gallon containers from the grocery store could fit, but all of the container plastic and imperfect stacking completely change things.

Based on this volume in ft³, the amount of fertilizer to use can be determined with the statement:

0.5 cp fertilizer = 0.5 ft³

and some dimensional analysis:

(0.00438 ft³ soil)*(0.5 cp fertilizer)/(0.5 ft³ soil) = 0.00438 cp fertilizer

This is approximately 0.21 (a fifth) of a teaspoon, or nearly 1 (1.036) of a mL of fertilier, per container.

EDIT: I was just thinking if you are looking for a way to handle this methodically without going smaller than a teaspoon, you can combine 5 containers worth of soil in a bowl, add a whole teaspoon of fertilizer, then redistribute them.