90 



HOPS. 



such as propagate from roots, can be effectually combated, 

 and even certain animal pests destroyed, and stones and 

 roots got rid of; and, finally, that the work facilitates the 

 -thorough mixing and loosening of the soil, as well as any 

 convenient displacement of the different layers, while its 

 thoroughness undoubtedly assists the satisfactory growth of 

 the plant. 



%■ 



-A 



II. 



MJ 



^ 



^ 



Fig. 18. — Field parcelled out in plots for hand trenching. 



With regard to the mixed system of trenching, the ground 

 is trench ploughed with a strong instrument to a depth of 

 20 to 24 inches, men armed with spades being set to work 

 behind the plough, to dig and turn over the bottom of the 

 furrows. Given a sufficient number of men to keep pace 

 with the plough the ground can be got over very quickly in 

 this way, and the soil is stirred to a depth of 20 to 24 inches. 

 Of course the work is not so thorough as where hand trench- 

 ing is practised exclusively, though less expensive, and in 



