Home-made KP-lite Fertilizer

[Mocchaccino]

Hey everyone,

I recently read through the threads and am going to prepare a KP-lite for my own. I would like to share my work and ask for opinions on it.

Disclaimer:
Firstly, the method in use was not accurate but it gave a general idea of the amount of each constituents.

Second, I would not want to spend extra money on just making my own fertilizer. It would not worth to spend hundreds on sophisticated analytical grade instruments or whatever to make the solution.

Resources:
 Analytical Grade Hydrated Calcium nitrate [Ca(NO3)2*4H2O]
 Epsom Salt [MgSO4*7H2O]
 Hyponex 30-10-10 (a commercial fertilizer in powder)
 Salifert Ca Test Kit
 Salifert Mg Test Kit
 Salifert K Test Kit
 API NO3 Test Kit


Preparing Stock Solution
Since I don’t have a balance so I am just using the spoon provided by the 30-10-10 Hyponex fertilizer who claimed the spoon weighs 1 gram. Of course that’s not scientific at all.


All three resources were prepared: 1 full spoon into 10 mL tap water


Measuring MgSO4
Since there’s no idea of the amount of solutes, I just made wild guess for all.
I tested it with Salifert Mg Test Kit (which tests for reef but it’s also compatible with soft water)

sample drawn 1 mL
top up to 10 mL
Fold Dilution 10
Titration end pt at 0.15
ppm projected 1275 ppm
ppm in actual stock 12750 ppm

Measuring Ca in CaNO3

Salifert Ca Test Kit

sample drawn 0.1 mL
top up to 12 mL
Fold Dilution 120
Titration end pt at 0.48
ppm projected 520 ppm
ppm in actual stock 62400 ppm

Measuring NO3 in CaNO3

API NO3 test kit

sample drawn 1 mL
top up to 10 mL
1st diluted sample drawn 0.1mL
Top up to 15mL
Fold Dilution 1500
Titration end pt at
ppm projected 80 ppm
ppm in actual stock 120000 ppm
ppm recommended 80 ppm
Recommendation:

Measuring K in Hyponex 30-10-10

Although it’s colored in orange, the diluted sample became pale in orange and did not affect the reading since the titration end point was in strong blue.

sample drawn 0.5 mL
top up to 15 mL
Fold Dilution 30
Titration end pt at 14
ppm projected 360 ppm
ppm in actual stock 10800 ppm

P and N in Hyponex 30-10-10

There isn’t any test available to me to measure P2O5. Only 1 out of 30 parts, as illustrated by the Hyponex manual, was claimed to be true NO3. I assume the rest of them are mixtures or pure urea which there isn’t any test I own can test for it. Hence I just trust the ratio provided and projected the amount.
P = 10800 ppm
N = 32400 ppm

Conclusion:

CaNO3 stock solution: dilute to 1:1500 where Ca = 62400/1500 = 41 ppm ; NO3 = 120000/1500 = 80ppm
Epsom Salt solutionL dilute to 1:1000 where Mg = 12750/1000 = 12.75ppm
Hyponex 30-10-10 stock: dilute to 1:2000 where K = 10800/2000 = 5 ppm; N=15 ppm; P=5ppm
　 　 　 　 　
Constituents/ppm N(80+15=95) P(5) K(5) Ca(41) Mg(12)

Ratio 19 1 1 8 2

Comments?

 

[naoki]

When I measured Epsom Salt (MgSO4 7 H2O), 1 teaspoon is about 4.76365g. I used 5 different measuring spoon (1/8tsp, 1/4tsp, 1/2tsp, 1tsp, 1TBS), measured 3 times per spoon. Then I got the number from the linear regression. Different shape measuring spoons would make difference, but it is probably good enough.

So 1 tsp contains 469.75488 mg of Mg and 619.63979mg of S. 1/8 tsp per gallon will give you 15.5ppm Mg and 20.5ppm S.