( ( ( The ( major reservoir ) ) ( of nitrogen ) ) ( ( is ( ( ( the atmosphere ) , ) ( which ( is ( ( ( 80 % ) ( nitrogen gas ) ) ( -LRB- ( N2 -RRB- ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ major) (NN reservoir)) (PP (IN of) (NP (NN nitrogen)))) (VP (VBZ is) (NP (NP (DT the) (NN atmosphere)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (ADJP (CD 80) (NN %)) (NN nitrogen) (NN gas)) (PRN (-LRB- -LRB-) (NP (NNP N2)) (-RRB- -RRB-)))))))) (. .)))
The major reservoir of nitrogen is the atmosphere, which is 80% nitrogen gas (N2).
(ROOT (S (NP (NN Nitrogen) (NN gas)) (VP (VBZ comprises) (NP (NP (QP (RB about) (NNS three-fourths))) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN atmosphere))))) (. .)))