PREPARATION OF THE LAKD. 363 



and the most expeditious hi performance. Trenching 

 is done by moving the soil two or more spits deep, and 

 either burying the surface soil and bringing the subsoil to 

 the top, or by loosening, and breaking up, and turning 

 over the under soil, and replacing the surface soil over it 

 in its original position. The nature of the soil usually 

 determines which is the best method. When the surface 

 and subsoils are pretty homogeneous in their physical 

 characters, it is generally thought best not to bring up the 

 subsoil, but merely to break up and invert it without 

 bringing it up to the top. Where, however, the subsoil is 

 very compact and different from the surface, it is better 

 to break it up thoroughly and remove it to the top, as 

 otherwise it is apt to cohere again, and in a few years 

 become perhaps as indurated and impervious to the roots 

 of the plants as it was previously to being trenched. The 

 cost of the work (trenching) depends upon the nature of the 

 soil and the depth it is to be moved from 6d to Is. Qd. per 

 square rod may be taken as the average rate of payment 

 for the work. By ploughing and subsoiling the soil may 

 be moved equally deep,. and at a much cheaper rate. Six 

 horses with the Kent plough will turn a furrow from 10 to 

 1 2 inches deep, and the subsoil plough with four horses 

 will follow it, taking 'a depth of some 6 inches more. 

 These would get over about two-thirds of an acre a day, 

 at a cost of 40s., or at the rate of 60s. per acre. 



Here it is that our new auxiliary, the steam-plough, 

 shows the great and economical powers it possesses. This 

 is the sort of work, especially on the strong cohesive soils, 

 in which it can be applied to great advantage. In the 

 report 1 of the trials of the Chester meeting, we find that 

 the soil (a strong clay loam) was turned over to the 

 depth of 14 inches by the steam -plough, at a cost, 

 including all expenses, of 18s. 4c. per acre, and that it 



1 Roy. Agri. Soc. Jour., vol. xix. p. 326. 



