( Then ( we ( ( invoked ( ( each ( of ( the ( four elements ) ) ) ) ( necessary ( for ( ( the ( plants ' ) ) growth ) ) ) ) ) . ) ) )
(ROOT (S (RB Then) (NP (PRP we)) (VP (VBD invoked) (S (NP (NP (DT each)) (PP (IN of) (NP (DT the) (CD four) (NNS elements)))) (ADJP (JJ necessary) (PP (IN for) (NP (NP (DT the) (NNS plants) (POS ')) (NN growth)))))) (. .)))
Then we invoked each of the four elements necessary for the plants' growth.
(ROOT (S (NP (NNP Plant) (NNP nutrition)) (VP (VBZ is) (NP (NP (DT the) (NN study)) (PP (IN of) (NP (NP (DT the) (JJ chemical) (NNS elements)) (ADJP (JJ necessary) (PP (IN for) (NP (NN plant) (NN growth)))))))) (. .)))