  Phosphorus (P) is considered to be one of the key elements for life, making
it an important element to look for in the abundance analysis of spectra of
stellar systems. Yet, there exists only a handful of spectroscopic studies to
estimate the P abundances and investigate its trend across a range of
metallicities. We have observed full HK band spectra at a spectral resolving
power of R=45,000 with IGRINS instrument. Abundances are determined using SME
in combination with 1D MARCS stellar atmosphere models. The investigated sample
of stars have reliable stellar parameters estimated using optical FIES spectra
(GILD; J\"onsson et al. in prep.). In order to determine the P abundances from
the 16482.92 Angstrom P line, we take special care of the CO($\nu=7-4$) blend.
We determine the C, N, O abundances from atomic carbon and a range of
non-blended molecular lines (CO, CN, OH) which are aplenty in the H band region
of K giant stars, assuring an appropriate modelling of the blending
CO($\nu=7-4$) line. We present [P/Fe] vs [Fe/H] trend for 38 K giant stars in
the metallicity range of -1.2 dex $<$ [Fe/H] $<$ 0.4 dex. We find that our
trend matches well with the compiled literature sample of prominently dwarf
stars and limited number of giant stars. Our trend is found to be higher by
$\sim$ 0.05 - 0.1 dex compared to the theoretical chemical evolution trend in
Cescutti et al. 2012 resulting from core collapse supernova (type II) of
massive stars with the P yields from Kobayashi et al. (2006) arbitrarily
increased by a factor of 2.75. Thus the enhancement factor might need to be
$\sim$ 0.05 - 0.1 dex higher to match our trend. We also find an empirically
determined primary behaviour for phosphorus. Furthermore, the phosphorus
abundance is found to be elevated by $\sim$ 0.6 - 0.9 dex in two metal poor
s-enriched stars compared to the theoretical chemical evolution trend.
