Yara N-Tester User manual

N-Tester
Instruction manual

Imprint
Issue: 03.2013
Software version: 2.00 (generic)
Manufacturer / distributor:
YARA GmbH & Co. KG
Hanninghof 35
48249 Dülmen
Germany
Contact data can be found on the back page of this
manual.
Information:
The information included in this manual corresponds with
our current state of knowledge and is no claim for
completeness.
The application rates that are recommended using this
device are non-binding and do not form a contractual
relationship between the receiver and Yara.
Warranty or liability for correctness of the fertilizer
recommendation is exempted in individual cases as the
location and the cultivation conditions may be substantially
different. The information provided does not replace any
individual consultation.

Issue: 03.2013 (EN) 3
Table of contents
Information for correct use..................................... 4
Correct use .........................................................................4
Application errors................................................................5
Exclusion of warranty..........................................................5
Description............................................................... 6
Mode of function .................................................................6
Scope of supply ..................................................................6
Technical specifications......................................................7
Operating conditions...........................................................7
Overview of the device........................................................8
Operation and application .................................... 10
Starting up ........................................................................10
Requirements for reliable measurements .........................10
Carry out measurements ..................................................11
Internal calibration .................................................12
Action.....................................................................12
Field.......................................................................13
N-Tester reading...............................................................15
History...............................................................................16
System functions...............................................................17
Setting the language..............................................17
Maintenance and servicing................................... 18
Calibration .............................................................18
Resetting the N-Tester to factory defaults .............20
Updating the N-Tester software.............................21
Replacing the batteries..........................................22
Cleaning ................................................................22
Transport and storage ...........................................22
Disposal.................................................................23
Troubleshooting .................................................... 24

4 Issue: 03.2013 (EN)
Information for correct use
Please read this instruction manual carefully before using
the N-Tester. Incorrect use of the N-Tester can lead to
excessive or insufficient fertilizing which may result in
unnecessary costs.
Correct use
The chlorophyll concentration in leaves is measured as the
mean of 30 individual measurements.
The following points must be observed in order to use the
device in a correct manner:
▪Requirements for reliable measurements from page 10
▪Adherence to the service and maintenance instructions
from page 188
The device can be used during light rain. The device must
never be completely soaked or immersed in water.

Issue: 03.2013 (EN) 5
Application errors
Observe the following points in order to avoid incorrect
measurements:
▪do not take measurements during incorrect
development stages
▪do not perform measurements on insufficiently
developed leaves
▪do not perform all measurements on the same plant
▪do not perform all measurements on a small area of
the field
▪do not use the N-Tester on areas with sulphur
deficiency
▪do not use with visible drought stress (leaves rolled
together)
▪do not measure using an old software version
Exclusion of warranty
The manufacturer is not liable for the following damages to
the device:
▪damage to the device following impacts or vibration
▪damage to the device resulting from penetrating
moisture
▪damage to the display resulting from pressure
application and scratches
▪malfunctions due to damage to the measuring head
and scratches, etc. in the sample slot
▪malfunctions from cleaning the sample slot with
cleaning agents containing alcohol or other chemicals
▪damage caused by heat or intensive solar radiation:
The device must not be placed in the immediate
vicinity of heat sources or be exposed to direct
sunlight.
▪incorrect disassembly of the device
▪incorrect storage (see 'Transport and storage' on
page 22)

6 Issue: 03.2013 (EN)
Description
Mode of function
The chlorophyll concentration in leaves is measured using
the N-Tester. The mean of 30 individual measurements is
displayed after successful application. The youngest fully
developed leaf is illuminated in two wavelength ranges
using light that is absorbed in different intensities by the
chlorophyll. The remaining transmitted light is captured in a
photodiode and converted to a measuring value.
A minimum of 30 individual measurements is required to
provide a representative reading. Individual values that
deviate considerably (faulty measurements) are not
considered.
Scope of supply
▪N-Tester
▪Hand strap (for the eyelet on the N-Tester)
▪Batteries
▪Calibration disc
▪Belt bag
▪USB cable
▪Transport box

Issue: 03.2013 (EN) 7
Technical specifications
Size of the sample slot:
2 x 3 mm
Maximum leaf thickness:
1.2 mm
Maximum insertion depth
(with depth stop):
12 mm
Light source:
2 LEDs
Receiver:
Silicon photo diode
Display:
LCD
Batteries:
2 x AA, 1.5 V (alkaline-manganese)
Service life of a battery:
approx. 20,000 measurements
Dimensions:
164 x 78 x 49 mm
Weight (without batteries):
200 g
Degree of protection
against water (EN 60529):
Category 4
The device may be used when it is
raining but must never be cleaned
under running water.
Operating conditions
The N-Tester is suitable for the following operating
conditions:
▪0 to +50 °C
▪Relative humidity < 85% at up to 35°C without
condensation

8 Issue: 03.2013 (EN)
Overview of the device
1. Measuring head
2. Finger rest
3. Power switch
4. ESC: Cancel / return to the previous display
5. Enter button: Confirm selection
6. USB connection cap
7. Hand strap
8. Battery chamber cover
9. Strap eyelet

Issue: 03.2013 (EN) 9
10. DOWN: Moves the cursor / line marking down or to the
right
11. UP: Moves the cursor / line marking up or to the left
12. Calibration disc
13. LCD panel:
Displays data and other information.
14. Sliding depth stop:
In order to allow the leaf to be measured with the same
distance to the leaf edge each time. Can be adjusted
or removed when required.
15. Sample slot
16. Center line:
Indicates the center of the measuring area

10 Issue: 03.2013 (EN)
Operation and application
Starting up
–Insert the batteries.
The device is ready for use.
Requirements for reliable measurements
▪The N-recommendations apply only for certain
development stages.
▪At least 30 measurements must be carried out on 30
different plants per field.
▪In order to obtain a representative average reading, the
measurements must be carried out randomly
distributed across the field.
▪When measuring, avoid any atypical areas of the field
(e.g. areas with distinctly different soil properties, such
as sand banks or similar)!
▪Measuring point: The measurement must be carried
out in the middle of the leaf blade of the youngest fully
developed leaf. Measurements on not fully developed
leaves may lead to increased recommendations.
Example, BBCH 32: Measuring point at stage ‘Stem
elongation (node 2 at least 2 cm above node 1)’
Example, BBCH 47: Measuring point at stage 'Booting’
(flag leaf sheath opens)
▪Variety: Differences in the varieties need to be
considered, e.g. by correction factors.
▪Sulphur deficiency: S deficiency such as N deficiency
leads to the leaves being brighter. Therefore a
sufficient S supply has to be ensured when using the
N-Tester. Other nutrients do not have any significant
influence.

Issue: 03.2013 (EN) 11
▪Weather: The N-Tester is not able to display future N
soil supplies, e. g. from applied N that plants have not
yet absorbed due to drought. Therefore, use your
experience when evaluating the fertilizer
recommendation.
▪Drought: Intensive drought can lead to an increased
chlorophyll concentration in the leaves and to wrong N-
Tester readings. Therefore avoid measuring plants that
suffer from visible drought stress (e.g. leaves rolled
together).
The following factors do not have an effect on the N-Tester
reading:
▪Time of the day when measuring
▪Pesticides
▪Moisture on the leaf
▪The use of strobilurins
▪Yield level
Carry out measurements
Each measurement comprises the following steps:
▪Calibrate internally (after the device has been switched
off)
▪Measure 30 x
▪Read off and evaluate the measuring result

12 Issue: 03.2013 (EN)
Internal calibration
–Turn on the device.
Note:
If foreign language text appears, please see page 177 to
find out how to change the language.
N-Tester
©2013
AP 2.02 30002366
The following is shown in the display:
▪©2013: year of the validity of the software
▪AP 2. 02: Version of the software
▪3000 2366 : Serial number of the device
Pinch empty
sample head for
about 2s.
An internal calibration is necessary each time the device is
switched on. No leaf must be inserted.
The calibration was successful when a single beep can be
heard.
Calibration
is faulty.
Turn off the
device.
If three consecutive beeps can be heard, the calibration
was not successful. You may have opened the measuring
head too early or you have not pressed them together
completely.
–Switch the device off and back on and repeat the
internal calibration.
Action
After successful calibration you can choose the next action.
Action
Measurement
Settings
–Select Measurement.
–Press .

Issue: 03.2013 (EN) 13
Field
Field
ABCDEFGHIJKLMNOP
QRSTUVWXYZ-----
_
–To select a field name, select a letter by using or
.
–Press .
–Select the next letters in the same way (max 16
letters).
–When the field name is completely selected:
–Press .
To return to the main program without selection:
Press .
Measuring
Please note:
▪The sample slot (in the measuring head) must be kept
clean during the whole series of measurements.
▪Intensive solar radiation can influence the result. Hold
the N-Tester so that it is covered by the shadow of
your body.
▪Avoid using grained or thick points on the leaf.
–Hold the N-Tester on the first plant and place the leaf
blade of the youngest fully developed leaf in the
measuring head.
Take samples
on 30 youngest,
fully developed
leaves.
–A total of 30 leaves must be measured before the N-
recommendation is displayed.

14 Issue: 03.2013 (EN)
The sample slot (2 x 3 mm) must be covered completely.
Both markings correspond to the center line of the
measurement area.
If necessary, the depth stop can be moved a little to adapt
to the width of the leaf.
1of 30
valid
measurements
–Press the measuring head together until a beep can
be heard.
23 of 30
valid
measurements
–Measure more leaves distributed equally across the
field. The current number of successful measurements
is displayed.
Please
repeat the
measurement.
Unsuccessful measurements will be indicated by several
consecutive beeps.

Issue: 03.2013 (EN) 15
Delete the last value
23 of 30
valid
measurements
If you have made an incorrect measurement this
measurement can be deleted.
–Press .
Delete?
last sample
entire series
continue
–Select last sample and press .
Note:
In order to cancel deletion, you can press again or
select 'continue' and confirm with .
22 of 30
valid
measurements
The last sample has been deleted.
Delete an entire series
Delete?
last sample
entire series
continue
If you delete the entire series, you will return to the start of
the measurement and all readings taken so far will be
dismissed.
N-Tester reading
N-Tester
649
The average N-Tester reading from 30 measurements is
displayed.

16 Issue: 03.2013 (EN)
Start a new series of measurements
Start a new series of measurements using .
New measurem.
New selection
Same field
Back
_
–To start a new measurement in a new field select New
selection using or and press .
Now you are back in the menu Field.
–To start a new measurement in the same field select
Same field using or and press .
–Now you can take a new measurement.
–To go back select Back
If you don’t want to make a new measurement first select
New measurement, then press .
When you are back in Action the display has changed.
History
Action
Measurement
History
Settings
–You can select History (this point appears after you
have done measurements) using or and press
.
Series 2/5
ABC
_
(333)
–Now you see how many series of measurements you
have done (5), the field name (ABC) of the shown
measurement, the number of the measurement (2)
and the N tester value (333).
–To return to the action menu press .

Issue: 03.2013 (EN) 17
System functions
Setting the language
Action
Measurement
History
Settings
–From within the Action menu select Settings using
or and press .
Settings
Device test
Language
–Select Language.
–Press .
To return to the main program without selection:
–Press .
Language
English
Deutsch
Italiano
Select your preferred language by pressing or ..
Press to make your decision.
The language is changed immediately.
Once you have confirmed the selection, you will return to
Settings.

18 Issue: 03.2013 (EN)
Maintenance and servicing
Calibration
If you have not used the N-Tester for longer periods
(several weeks), the calibration should be checked using
the calibration disc supplied.
–Take out the calibration disc to the front.
A special calibration disc belongs to every device. The
serial number of the device (1) and the serial number of the
calibration disc (2) must correspond with each other.
Action
Measurement
History
Settings
–From within the Action menu select Settings using
or and press .
Settings
Device test
Language
–Select Device test.
–Press .
Return to the main program without selection:
–Press .

Issue: 03.2013 (EN) 19
Insert the blue
calibration disc
and take a
measurement.
–Press the measuring head together until a beep can be
heard.
–Compare the value measured with the value (3) on the
rear of the calibration disc.
The deviation must be no greater than the maximum
deviation indicated on the disc (4).
Calib. value:
63,4
Note:
If the value measured does not lie within the specified
tolerance range, a reliable fertilizing recommendation is not
possible. In such cases, please contact YARA directly (see
the reverse of this manual).

20 Issue: 03.2013 (EN)
Resetting the N-Tester to factory defaults
To reset the N-Tester to factory defaults switch the device
off, hold down and together and power the device
on again.
CLEAR PSA/PPA
Device settings
have been reset
to defaults.
–Now all settings have been reset to factory defaults.
–You must switch the device off to do a new
measurement
Settings have
been reset to
their default
values.
–When you start it again it informs you, that it was
reset, then the normal program appears.
–You can now start new measurements and settings.