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.