Luca Incrocci (incrocci@agr.unipi.it)

University of Pisa, Pisa, Italy

Euphoros Workshop – Szentes (HU), 28 June 2011

Chemistry of nutrient solution Chemistry of nutrient solution --

Use of a Nutrient Solution calculatorUse of a Nutrient Solution calculator

1) pH: 5.5 – 6.5

2) Electro-Conductivity (EC) : 1.5 – 4.0 dS/m

3) Recipe: concentration (milli- or micro-moles per liter) of 12 nutrients

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Macronutrients

(mmol/l)

N

5-15

P

1-2

K

4-10

Ca

3-8

Mg

1-2

S

1-5

Micronutrients

(µµµµmol/l)

Fe

15-40

B

15-30

Zn

5-10

Mn

5-10

Cu

1-5

Mo

0.1-0.5

Main characteristics of NS Main characteristics of NS Main characteristics of NS Main characteristics of NS

Nutrient solution and pH: how much acid? Nutrient solution and pH: how much acid? Nutrient solution and pH: how much acid? Nutrient solution and pH: how much acid?

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1) H2CO3 +H2O HCO3− + H3O

+pKa

H2CO3 = 6.35

2) [HA] [HCO3-]W - [HA]

[H2O] [H3O+]

3) [H3O+] = [HCO3

-]W- [HA]

[HA]

4) pH = pKa + log ([HCO3-]W-[HA])/[HA])

[HA] = [HCO3-]W/(1+10pH-pKa)

=[HCO3-]Water - [HA]= [HA]

Target pH

[HA]

6.35 0.50 [HCO3-]W

6.00 0.70 [HCO3-]W

5.60 0.85 [HCO3-]W

Contribution of different types of ions to the EC of nutrient solution (NS) in closed substrate culture of greenhouse tomato. The values refer to newly-prepared NS or NS that was recirculated for 1-2 weeks.

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Fresh NS Rec. NS (7 days) Rec. NS (14 days)

EC

level (d

S/m

)Ballast ions Micronutrients Macronutrients

Accumulation of ballast ions in recirculating nutrient solutionsEC and nutrient concentration

04/19

Nutrient Solution calculator v1.0

• Free tool (Excel spreadsheet) developed by University of Pisa with the collaboration of dr. Ombódi Attila of the Szent István University.

•Input:

�Water composition;

�Crop recipe (also pH and EC); (It contains a database with 15 standard crop recipes);

�Fertilizer and acid nutrient content (it contains a database with the most used products)

�Fertigation system specification; 05/19

Nutrient Solution calculator

OUTPUT:

�calculation of the nutrient solution and its cost;

�calculation of stock nutrient solution ;

�salt precipitation test.

06/19

START

Vízvizsgálat eredménye

Mértékegységátalakító

Teszt(vízminıségellenırzése)

Tápoldatozó adatai

Recept az adottnövényhez

Recept adatbázis

Mőtrágyákés savak

Mőtrágyaadatbázis

Recept kiválasztása

Igen

Recept az adottnövényhezNem

pH és EC

Tápoldatmódosítása

Mőtrágyákés savak

kiválasztása

EredmEredméényny((nyomtatnyomtatááss))

Csapadékteszt

Hígításiarány

változtatása

Nem

Igen

SzSzáámmííttááss

A Tápoldat Kalkulátor folyamatábrája

07/19

Nutrient Solution calculator:Start page

08/19

Nutrient Solution calculator:Fertilizer and acid database

Check data:1) price2) composition

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Nutrient Solution calculator:Recipe database

User can modify or insert a new recipe

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Nutrient Solution calculator:Unit Converter tool

14/1514/1514/1514/15

Insert here the water composition in mg/l

Click to acquire the water composition in mmol/l

Nutrient Solution calculator:Input sheet (1)

1) Insert here the water composition in mg/l

2) Insert the fertigator parameter

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Nutrient Solution calculator:Input sheet (2)

3) Select the recipe,pH EC

4) Check the target nutrient solution

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Nutrient Solution calculator:calculation

Automatic calculation:1) choose the acids and

salts that could be used2) click on calculate

The expert user, could insert manually the values using the advice in the light-blue cell

When the element is in correct concentration appear a green colour in the cell.

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Nutrient Solution calculator:Report and print

1) Check the absence of salt precipitation in the stocks:2) You can apply a lower dilution

Summary of the input and output

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Nutrient Solution calculator:stock NS precipitation test

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NS ion concentration

1) user could identify the precipitated salt(s)

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Nutrient Solution calculator:Report and print

Output: �salts to prepare the stock NS solutions (A+B);�Its cost

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Conclusions

• In soilless culture the use of correct nutrient solution is important for the optimal plant growth and for maximizing its re-use;

• pH, EC and the nutrient ion concentrations are the main characteristics of a nutrient solution;

•Nutrient Solution calculator is a tool useful for the grower and the technician to manage and calculate the NS solution.

18/19

Thank you very muchThank you very much

for the attention!for the attention!

Dip. Biologia Piante Agrarie – Villa Victorine (Le Piagge, Pisa)19/19