Formula Analysis.

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Cylindra Beetroot and Pickling Gherkin seed packets.
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Three Pickling Gherkins let to grow as cucumbers.
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Cylindra Beetroot about half grown. After cooking most slices are the same size.
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The discussion on this page is fairly technical, so if you are not interested in designing your own formulations or looking at the analysis for the Starting Formula on the previous page, you may want to go to the next page.

It is essential that the macro fertilizers be analysed in designing a new formulation. The Trace Elements are present as traces and will not be analysed here ... but do not forget them, or your results may be disappointing, unless your water supply can provide them.

Along with the macro fertilizers in the Starting Formulation, Potassium Sulphate, Urea and Sulphate of Ammonia will be analysed as well. The latter two are not suitable for hydroponics, but are widely used for in-ground gardening.


Mono Ammonium Phosphate:
Also known as Ammonium Dihydrogen Phosphate.
Formula
Molecular Weight
Phosphorus content
Nitrogen content
NH4H2PO4
= 115.03
= 26.92%
= 12.17%

Calcium Nitrate:
Formula
Molecular Weight
Calcium content
Nitrogen content
Ca(NO3)2.4H2O
= 236.16
= 16.97%
= 11.86%

Potassium Nitrate:
Formula
Molecular Weight
Potassium content
Nitrogen content
KNO3
= 101.11
= 38.6%
= 13.85%

Magnesium Sulphate:
Also known as Epsom's Salts.
Formula
Molecular Weight
Magnesium content
Sulphur content
MgSO4.7H2O
= 246.48
= 9.86%
= 13.0%

Potassium Sulphate:
Also known as Sulphate of Potash.
Formula
Molecular Weight
Potassium content
Sulphur content
K2SO4
= 174.26
= 44.87%
= 18.4%

Urea:
Formula
Molecular Weight
Nitrogen content
CO(NH2)2
= 60.06
= 46.65%

Ammonium Sulphate:
Also known as Sulphate of Ammonia.
Formula
Molecular Weight
Nitrogen content
Sulphur content
(NH4)2SO4
= 132.14
= 21.20%
= 24.26%


Now to calculate the fertilizer active materials to make up 160 Litres of nutrient solution for the reservoir tank.

Solution #1.

Solution #1 contains 1000 g of Magnesium Sulphate made up to 4.0 Litres, and we use 1.0 mL/Litre, so use 160 mL in nutrient tank.
Now, 160 mL = 4.0% of 4.0 Litres.
Therefore solid Magnesium Sulphate = 4.0% 0f 1000 g = 40 g.
Therefore Magnesium = 9.86% of 40 g = 3.94 g,
and Sulphur = 13.0% of 40 g = 5.2 g.

Solution #2.

Solution #2 contains no active fertilizer material, but contains soluble Iron (a trace element).

Solution #3.

Solution #3 contains 400 g MAP made up to 4.0 Litres, and we use 2.0 mL/Litre, so use 320 mL in nutrient tank.
Now, 320 mL = 8.0% of 4.0 Litres.
Therefore solid MAP = 8.0% of 400 g = 32 g.
Therefore Phosphorus = 26.92% of 32 g = 8.61 g,
and Nitrogen = 12.17% of 32 g = 3.89 g.

Solution #4.

Solution #4 contains 1000 g of Calcium Nitrate made up to 4.0 Litres, and we use 4.0 mL/Litre, so use 640 mL in nutrient tank.
Now, 640 mL = 16.0% of 4.0 Litres.
Therefore solid Calcium Nitrate = 16.0% of 1000 g = 160 g.
Therefore Calcium = 16.97% of 160 g = 27.15 g,
and Nitrogen = 11.86% of 160 g = 18.97 g.

Solution #5.

Solution #5 contains 400 g of Potassium Nitrate made up to 4.0 Litres, and we use 6.0 mL/Litre, so use 960 mL in nutrient tank.
Now, 960 ml = 24.0% of 4.0 Litres.
Therefore solid Potassium Nitrate = 24.0% of 400 g = 96 g.
Therefore Potassium = 38.6% of 96.0 g = 37.0 g,
and Nitrogen = 13.85% of 96.0 g = 13.3 g.

Adding all of the active materials from the calculations above and tabulating them to show the amount present in 160 Litres of nutrient solution, the respective concentrations in milligrams per Litre and the recommended limits in milligrams per Litre, shown in brackets, we have:


Nitrogen
Phosphorus
Potassium
Magnesium
Calcium
Sulphur
= 36.2 g
= 8.6 g
= 37.0 g
= 3.9 g
= 27.2 g
= 5.2 g
= 226.0 mg/L
= 53.8 mg/L
= 231.2 mg/L
= 24.6 mg/L
= 169.6 mg/L
= 32.5 mg/L
= (140 - 300)
= (31 - 80)
= (160 - 300)
= (24 - 75)
= (100 - 400)
= (32 - 400)

The analysis above clearly shows that Magnesium and Sulphur are just above their lower recommended limits, so if you were re-designing this formula, it would be feasible to increase the Magnesium Sulphate (Epsom's Salts) content.

If you need clarification on any points, please feel free to E-mail me.

The next page shows Hints for Success. It brings everything together and fills in a few points that were omitted elsewhere.

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