Abstract:
This study was carried out to determine nitrogen, p
hosphorus, and potassium contents
of rangeland plants using spectral reflectance valu
e. The measurements were made in 1
m
2
area of different parts of a rangeland. A portable
spectroradiometer capable of
measuring the wavelength range of 325-1,075 nm of t
he electromagnetic spectrum was
used to collect spectral data. Spectral measurement
s were made in a rangeland while
nitrogen, phosphorus, and potassium content of the
plants were determined in a
laboratory. Stepwise linear regression was used to
select wavelengths to investigate
relationships between laboratory analysis results a
nd spectral data. According to the
result, significant relationships existed between p
redicted and measured nutrients, with
R
2
values of 0.85, 0.43, and 0.84 for nitrogen, phosp
horus and potassium, respectively.
While 11 wavelengths (R
609
,
R
647
,
R
651
,
R
654
,
R
669
,
R
675
, R
676
,
R
680
, R
721
,
R
727
,
R
760
) were used
in the equation for estimating nitrogen level, 2 wa
velengths (R
675,
R
680
) and fifteen
wavelength (R
410,
R
411,
R
417,
R
422,
R
460,
R
463,
R
468,
R
646,
R
651,
R
658,
R
669,
R
670,
R
674,
R
676,
R
682
)
were determined for phosphorus and potassium levels
, respectively. The results indicated
that the changes in nitrogen, phosphorus, and potas
sium content affected reflectance
values of the visible region of spectrum (especiall
y in the red regions) and, therefore,
spectral reflectance data could be used to estimate
the nitrogen, phosphorus and
potassium contents in rangeland plants.
Keywords:
Plant nutrient elements, Rangeland, Remote sensing
, Spectral reflectance.
