SUB-SOILIJTG, TREKCH PLOWING, TILLAGE. 57 



crop is growing, and it fulfills two important objects. 

 First, it extirpates weeds and keeps the land clean ; and 

 secondly, it stirs, loosens, and pulverizes the surface soil. 

 The extirpation of weeds is of course indispensable to 

 good cultivation. But the second 23rinciple of hoeing is 

 if possible still more important. Deep and continuous 

 hoeing is wonderfully eifective in promoting the growth 

 of plants. It prevents the soil reverting to its natural 

 solidity, admits air and water, and by breaking and sub- 

 dividing it, causes it to retain moisture and to j) resent 

 innumerable surfaces and fresh particles to the young 

 roots. The effect is visible in the faster growth of the 

 plants every time the earth is stirred about them. 



Hoeing, however, can only be practised in the case of 

 crops in drills or in hills. Broadcast work is thus incom- 

 patible with thorough cultivation, even in the case of 

 gram crops. If horse-hoeing is intended among the 

 grain crops, the drilling should corresi3ond with the 

 horse-hoe to be used. Drilling is equally indispensable 

 to all hand-hoeing. 



Steam CisUlvatlon. — In many cases tillage by the 

 wealthy farmer may, m part at least, be advantageously 

 performed by steam power. It (1) gives cheaper, deeper, 

 and more efficient tillage than horse power ; it (2) ena- 

 bles the work to be done with rapidity and at the best sea- 

 son ; it (3) enables land to be more quickly and effectually 

 cleaned and kept free from weeds ; it (4) promotes good 

 drainage by rendering tenacious soils more friable and 

 porous ; and it (5) not only effects a considerable diminu- 

 tion in the number of horses, but, by relieving tliem of 

 their heaviest work, enables you to keep those which are 

 still necessary at less expense. 



Of the two mam systems of cultivating by steam, the 

 double-engine system necessarily involves the largest out- 

 lay to begin with ; but where the farm is large enough to 



