( ( ( The ( highest ( nitrate concentrations ) ) ) ( in ( ground water ) ) ) ( ( occurred ( in ( sandy ( , ( well-drained soils ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJS highest) (NN nitrate) (NNS concentrations)) (PP (IN in) (NP (NN ground) (NN water)))) (VP (VBD occurred) (PP (IN in) (NP (JJ sandy) (, ,) (JJ well-drained) (NNS soils)))) (. .)))
The highest nitrate concentrations in ground water occurred in sandy, well-drained soils.
(ROOT (S (S (NP (DT This) (NN statement)) (ADVP (RB best)) (VP (VBZ describes) (NP (JJ sandy) (NNS soils)))) (: :) (S (NP (JJ sandy) (NNS soils)) (VP (VBP allow) (NP (NN water)) (S (VP (TO to) (VP (VB drain) (ADVP (RB quickly))))))) (. .)))
This statement best describes sandy soils: sandy soils allow water to drain quickly.