Agriculture Reference
In-Depth Information
copper, zinc, molybdenum, and chlorine. All these elements are important for crop
growth, which influences the quality and quantity of crop. The detection methods
and instruments for nutritional parameters are mainly based on chemical analysis
and laboratory detection. The nitrogen content of a crop is an indicator of using
fertilizer and the efficiency fertilizer absorbance. The main methods for nitrogen
content (total nitrogen content) detection in plants are the Kjeldahl method and the
Dumas combustion method. The Kjeldahl method may be broken down into three
main steps: digestion, distillation, and titration. Digestion is accomplished by boiling
a homogeneous sample in concentrated sulfuric acid. The end result is an ammo-
nium sulfate solution. Distillation is that excess base added to the digestion product
to convert NH
4
to NH
3
. Titration quantifies the amount of ammonia in the receiving
solution. The amount of nitrogen in a sample can be calculated from the quantified
amount of ammonia ion in the receiving solution. The nitrogen content can also be
transferred into protein content by a certain parameter based on a different detec-
tion object. In the Dumas combustion method, a sample is burned in an oxygen-rich
atmosphere at high temperatures, and the resulting gases are analyzed. By using
the Dumas method, the new technique offers a fast and easy alternative to classical
systems. The Dumas method serves as a more precise and efficient alternative to
the Kjeldahl method. Digestion, distillation, and titration can take up to 1.5 to 2 h.
With Dumatherm, protein analysis time can be reduced to 2.5 min. This translates
into a 98% time savings as compared to Kjeldahl. Precision is also increased. The
SPAD-502Plus enables quick and easy measurement of the chlorophyll content of
plant leaves without damaging the leaf. Chlorophyll content is one indicator of plant
health, and can be used to optimize the timing and quantity of applying additional
fertilizer to provide larger crop yields of higher quality with lower environmental
load. The SPAD-502Plus can be used for determining when and how much nitrogen
fertilizer should be provided to plants. Optimizing fertilization in this way leads to
not only greater yields of higher quality, but also results in less overfertilization,
reducing environmental contamination due to the leaching of excess fertilizer into
the soil and underground water. The main characteristics of SPAD-502Plus are as
follows: measurement method: optical density difference at two wavelengths; mea-
surement area: 2 × 3 mm; subject thickness: 1.2 mm maximum; subject insertion
depth: 12 mm (with stopper having position adjustable from 0 to 6 mm); light source:
two LED elements; receptor: one SPD (silicon photodiode); display: LCD panel
showing four-digit measurement value (values shown to first decimal place) and two-
digit number of measurements; trend graph of values in memory can also be shown.
Display range: -9.9 to 199.9 SPAD units; memory function: memory capacity for up
to 30 values; calculation/display of average of data in memory also possible; power
source: 2-AA-size alkaline batteries; battery life: more than 20,000 measurements
(when using new alkaline batteries under Konica Minolta test conditions); minimum
interval between measurements: approximately 2 s; accuracy: within ±1.0 SPAD
units (for SPAD value between 0.0 and 50.0 under normal temperature/humidity);
repeatability: within ±0.3 SPAD units (SPAD value between 0.0 and 50.0 with no
change in sample position); dimensions: 78 (
W
) ×164 (
H
) ×49 (
D
) mm; weight: 200 g
(excluding batteries). Some researchers also use the chlorophyll meter to measure
chlorophyll content and SPAD value instead of nitrogen content for convenience,
