( Ploughing ( ( exposes ( ( humus ( -LRB- ( ( partially ( decayed ( organic material ) ) ) -RRB- ) ) ) ( to ( rapid oxidation ) ) ) ) . ) )
(ROOT (S (NP (NNP Ploughing)) (VP (VBZ exposes) (NP (NP (NNS humus)) (PRN (-LRB- -LRB-) (VP (ADVP (RB partially)) (VBN decayed) (NP (JJ organic) (NN material))) (-RRB- -RRB-)) (PP (TO to) (NP (JJ rapid) (NN oxidation))))) (. .)))
Ploughing exposes humus (partially decayed organic material) to rapid oxidation.
(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)))) (. .)))