102 THE PEOPLE'S FARM AND STOCK CYCLOPEDIA. 



chemical action proceeds most rapidly when the soil is moist 

 and warm, the spaces between the particles being filled with 

 air. In the, -chapter on. drainage it is shown that this condition 

 of soil is secured by this me.thod. When the soil is water- 

 logged this process .of .change ceases altogether, and hence 

 manures applied to such a soil are without effect. 



Drainage, therefore, not only secures the condition of soil 

 best fitted for plant growth, but it also secures that chemical 

 action essential to fertility. 



When corn turns yellow and dies in a long wet spell, it is 

 not because as seems to be commonly supposed the corn is 

 " drowned out," but because the presence of excess of water in 

 the soil has stopped the chemical work, and the plant starves. 

 There is plenty of food all around it, but the process by 

 which that food is made available has ceased. The first ques- 

 tion to be considered in the improvement of a piece of land 

 is therefore : " Does it need draining ?" If it does, this should 

 first be attended to, as without it all other treatment will be 

 ineffectual. 



Cultivation. By thorough cultivation the soil is pulver- 

 ized and the quality of fineness secured. The soil is also 

 more exposed to the air, and chemical change is thus facili- 

 tated. Cultivation should be preceded by drainage when 

 needed and should usually be accompanied by the use of 

 manure. Cases are on record of fields, which had become 

 almost barren, but were restored to fertility by thorough culti- 

 vation. Cultivation to a small extent adds to the amount of 

 plant food in the soil, as by exposing so much surface to the air 

 it causes an increased absorption of ammonia from the air, but its 

 principal value consists in the fact that it renders available ma- 

 terial already present in the soil. 



Manures. These are usually divided into three classes 

 barn-yard manures, green manures, and commercial manures. 

 They act in two different ways : first, by supplying plant food ; 

 second, by rendering available plant food already present. 

 Some manures act in one way, some in the other, and many 

 in both. 



