CULTIVATION. 89 



increased activity results in quicker oxidation, and the 

 production of more heat and acids which later help in 

 weathering the mineral part of the soil. The organisms 

 in the roots of the leguminous plants are better developed ; 

 they obtain more nitrogen gas and are able to fix more of 

 this substance to the clear profit of the farmer. 



The chemical effects of tillage are chiefly the result of 

 the greater activity on the part of the living bodies in the 

 soil. The total result of good tillage is an increase in the 

 root system of the crop, the absorption of more food from 

 the atmosphere, the fixation of more nitrogen to enrich 

 the land and the farmer, and the quicker decomposition of 

 the bodies in the soil. 



The fineness of tilth obtained from expending a certain 

 amount of labour varies with the character of the soil. 

 The production of a good tilth in clay soils is always dif- 

 ficult but it is made easier when the soil is manured Avith 

 bulky organic manures, when it is mixed with sand, and 

 when large quantities of lime are applied. Salt, nitrate 

 of soda, and sulphates generally, assist in destroying the 

 puddling tendency of clay soils when they are dissolved 

 in the soil water. Carbonate of soda in any considerable 

 quantity in the soil renders it more sticky and difficult to 

 pulverise. The ideal tilth is obtained when the soil clods 

 are broken up so that each particle is separated from its 

 neighbour, and the particles are well mixed in relation to 

 their former positions. A long exposure of the open soil 

 to the atmosphere barefallowing results in a better tilth, 

 as the natural elements have longer time to act and conse- 

 quently leave a greater impression. The gradual drying 



