text:  Stephens expresses a decided opinion in favour of trench-ploughing in the following passages:-- "I have no hesitation in expressing my preference of trench to subsoil ploughing: and I cannot see a single instance with the sole exception of turning up a very bad subsoil in large quantity in which there is any advantage attending subsoil that cannot be enjoyed by trench ploughing: and for this single drawback of a very bad subsoil trenching has the advantage of being performed in perfect safety where subsoil ploughing could not be without previous drainage