16
EXCESS EFFECTS
• reduced absorption of calcium and magnesium
• increase of water consumption
• increase of the substrate salinity
IRRIGATION WATER (LOW RANGE)
In agricultural areas it is quite common to find altered values in the
chemical composition of irrigation waters. The problem concerns mostly
the high nitrate concentration, usually determined by excessive fertili-
zation or irrational liquid manure spreading. The analysis of irrigation
waters allows us to find out which are the substances present in major
or minor quantity and to organize an advantageous fertilization plan.
For example, if the quantity of water utilized for crop cultivation is 250
mm/ha (= 2500000 L/ha) and the nitrate (NO
3
-
) concentration is
150 mg/L (34 mg/L as nitrate-nitrogen NO
3
-N), soil receives 85 kg/
ha of nitrogen. In choosing type and quantity of fertilizer to be used, it
is important to consider this information, in order not to waste fertilizer
nor to induce soil pollution.
NUTRIENTS SOLUTIONS (MEDIUM AND HIGH RANGE)
The nutrients requirements of the plants are determined by the type of
plant, its age and the environmental conditions. The control of chemi-
cal composition of nutrients solutions given to the plants is an operation
that allows a correct preparation of the fertilizer. In analyzing the
solution, it is possible to choose between medium range and high
range values, depending on the concentration of substances.
Medium range usually covers the analysis of residual solutions in
recycling systems. The nutritive elements are differently absorbed by
the plants, hence the nutrient solution loses substances, becomes
impoverished and must be enriched.
High range normally corresponds to the typical values of nutrients
solutions. It is therefore possible to verify that the solution given to the
plants contains the correct quantities of nutritive substances.
37
SPECIFICATIONS
Range
0 to 100 mg/L
Resolution
1 mg/L
Accuracy
±5 mg/L ±4% of reading
Typical EMC Dev.
±1 mg/L
Light Source
Tungsten lamp with narrow band interference
filter @ 525 nm
Method
Adaptation of the
Standard Methods for the
Examination of Water and Wastewater, 18
th
edition,
Amino Acid method. The reaction be-
tween phosphorus and reagents causes a blue
tint in the sample.
REQUIRED REAGENTS
Code
Description
Quantity
HI 93706
A
-0
Molybdate
10 drops
HI 93706
B
-0
Amino Acid Powder
1 packet
REAGENT SETS
HI 93706-01
Reagents for 100 tests
HI 93706-03
Reagents for 300 tests
For other accessories see page 48.
MEASUREMENT PROCEDURE
Note: for sample preparation follow the NUTRIENTS SOLUTION (HR)
procedure at page 19.
Phosphorus HR
PHOSPHORUS HIGH RANGE
• Select the program number corresponding to Phosphorus HR on
the secondary LCD by pressing PROGRAM
t
and
s
.
• Fill the cuvet with 10 mL of unreacted
sample (up to the mark) and replace
the cap.
• Place the cuvet into the holder and
ensure that the notch on the cap is
positioned securely into the groove.
• Press ZERO and “SIP” will blink on
the display.
1
0
m
L
