CULTIVATION. 93 



plough draught being beyond the power of a pair of oxen. 

 The native plough under ordinary circumstances runs 

 about sixteen centimetres deep, and the balance plough 

 twenty ; both are run deeper, two to four centimetres, 

 when cross ploughing. 



When the land is ploughed to a greater depth than 

 twenty centimetres, the operation is called "subsoiling." 

 Subsoilingis carried out by a special plough, by a European 

 followed by a native plough, or by steam tackle. Subsoiling 

 may entail the mixing of soil and subsoil, or it may be 

 carried out by simply stirring the subsoil without bringing 

 it to the surface. Subsoiling permits of and encourages 

 the production of a more extensive root system, it regu- 

 lates the porosity and permeability of the soil to an increased 

 depth, it ensures a more extensive preparation of plant 

 food by the weathering agents, it roots out deep seated 

 weeds, and consequently in Dearly every case gives an 

 increased crop. This increased yield is most pronounced 

 in the case of deep-rooted plants and least with cereals 

 grown directly after the Subsoiling. Before undertaking 

 extensive subsoil operations in which it is intended to mix 

 the soil and subsoil, it is necessary to first try the effect 

 of this tillage over a small area because sometimes when 

 the subsoil is of an undesirable nature, it is best to keep it 

 as far out of sight as possible. It would be a great mistake 

 to mix a heavy loam with a clay subsoil ; on the other hand 

 the mixing of a clay with a sandy subsoil or vice versa 

 would have a good and lasting effect. Simply stirring a 

 bad subsoil would always give favourable results. Mixing 

 soil with raw poor subsoil, and bury ing the good soil in a 



