CHAPTER III. 



SOIL MANAGEMENT— TILLAGE, IRRIGATION, 

 DRAINAGE AND BRAK SOILS 



TILLAGE. 



Jethro Tull (1674-1741) made the statement " tillage is 

 manure," his belief being that if soil particles are sufficiently 

 fine they can be absorbed by the plant. Although the reason 

 he gave was incorrect, nevertheless the practice resulting 

 from his belief proved to be substantially correct. 



Tillage has been defined as " the manipulation of the 

 soil by means of implements so that its structural relation- 

 ships may be improved for crop growth." It includes the use 

 of all those implements that are employed to stir the soil in any 

 way in the practice of crop production. The most common 

 operations performed with these implements are ploughing, 

 harrowing, rolling and cultivating. 



Objects of Tillage. — These may be briefly summarised 

 as follows : — 



1. To stir and loosen the entire soil to a sufficient depth 

 for the roots of plants to extend themselves fully. 



2. To pulverise the soil and to mix thoroughly its consti- 

 tuent parts. 



3. To develop various degrees of structure and uni- 

 formity of soil conditions suitable for the planting of seeds and 

 the setting of plants. 



4. To modify the movements of moisture and air in the 

 soil. 



5. To place beneath the surface manure, stubble, stalks, 

 and other organic matter, where it will be out of the way and 

 where it will be rapidly converted into humus. 



B 17 



