Euphoros Workshop – Szentes (HU), 28 June 2011
Chemistry of nutrient solution Use of a Nutrient Solution calculator
Luca Incrocci ([email protected])
University of Pisa, Pisa, Italy
Main characteristics of NS
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
Macronutrients
(mmol/l)
Micronutrients
(µ
µmol/l)
N
P
K
Ca
Mg
S
5-15
1-2
4-10
3-8
1-2
1-5
Fe
B
Zn
Mn
Cu
Mo
15-40
15-30
5-10
5-10
1-5
0.1-0.5
2/19
Nutrient solution and pH: how much acid?
1) H2CO3 +H2O
= [HA]
2)
[HA]
[H2O]
3)
[H3O+]
HCO3− + H3O+
pKaH2CO3 = 6.35
=[HCO3-]Water - [HA]
[HCO3-]W - [HA]
[H3O+]
= [HCO3-]W- [HA]
[HA]
4) pH = pKa + log ([HCO3-]W-[HA])/[HA])
Target
pH
[HA]
6.35
6.00
5.60
0.50 [HCO3-]W
0.70 [HCO3-]W
0.85 [HCO3-]W
[HA] = [HCO3-]W/(1+10pH-pKa)
3/19
EC and nutrient concentration
Accumulation of ballast ions in recirculating nutrient solutions
Ballast ions
Micronutrients
Macronutrients
EC level (dS/m)
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Fresh NS
Rec. NS (7 days)
Rec. NS (14 days)
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.
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
A Tápoldat Kalkulátor folyamatábrája
START
Mértékegység
átalakító
Teszt
(vízminıség
ellenırzése)
Vízvizsgálat
eredménye
Recept az adott
növényhez
Mőtrágyák
és savak
Tápoldatozó adatai
Recept
adatbázis
Mőtrágya
adatbázis
Recept az adott
Recept
kiválasztása Nem növényhez
Csapadék
teszt
Igen
pH és EC
Tápoldat
módosítása
Mőtrágyák
és savak
kiválasztása
Hígítási
arány
változtatása
Igen
Számítás
Eredmény Nem
(nyomtatás)
07/19
Nutrient Solution calculator:
Start page
08/19
Nutrient Solution calculator:
Fertilizer and acid database
Check data:
1) price
2) composition
09/19
Nutrient Solution calculator:
Recipe database
User can modify or
insert a new recipe
10/19
Nutrient Solution calculator:
Unit Converter tool
Insert here the water composition in mg/l
Click to acquire the water composition in mmol/l
14/15
Nutrient Solution calculator:
Input sheet (1)
1) Insert here the water composition in mg/l
2) Insert the fertigator parameter
12/19
Nutrient Solution calculator:
Input sheet (2)
3) Select the recipe,
pH
EC
4) Check the target nutrient solution
13/19
Nutrient Solution calculator:
calculation
Automatic calculation:
1) choose the acids and
salts that could be used
2) click on calculate
When the element is in
correct concentration
appear a green colour in
the cell.
The expert user, could insert
manually the values using the
advice in the light-blue cell
14/19
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
15/19
Nutrient Solution calculator:
stock NS precipitation test
1) user could identify the precipitated salt(s)
NS ion
concentration
14/15
16/19
Nutrient Solution calculator:
Report and print
Output:
salts to prepare the
stock NS solutions
(A+B);
Its cost
17/19
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 much
for the attention!
Dip. Biologia Piante Agrarie – Villa Victorine (Le Piagge, Pisa)
19/19