( ( ( ( This ( organic material ) ) or ) ( `` ( humus '' ) ) ) ( ( is ( added ( to ( ( the soil ) ( when ( organisms ( like ( plants decay ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT This) (JJ organic) (NN material)) (CC or) (NP (`` ``) (NNS humus) ('' ''))) (VP (VBZ is) (VP (VBN added) (PP (TO to) (NP (NP (DT the) (NN soil)) (SBAR (WHADVP (WRB when)) (S (NP (NNS organisms)) (VP (VBP like) (NP (NNS plants) (NN decay))))))))) (. .)))
This organic material or &quot;humus&quot; is added to the soil when organisms like plants decay.
(ROOT (S (NP (NP (DT The) (JJ decayed) (NNS remains)) (PP (IN of) (NP (VBG living) (NNS organisms)))) (VP (VBZ is) (VP (VBN called) (NP (NNS humus)))) (. .)))