SMALL HOLDINGS 113 



the food v/hich plants appropriate, but those 

 invisible germs which are known as bacteria, 

 and which are necessary in its preparation. 

 Thus, although farm-yard manure contains 

 nitrogen, phosphoric acid, and potash — all 

 of which are essential to plants — these 

 materials are not available until it has 

 passed through a process of decomposition 

 in which the micro-organisms of the soil 

 play an important part. 



Again, we have referred to the fact that 

 leguminous plants are enabled to obtain 

 nitrogen from the air with the help of specific 

 bacteria, but if the seed is sown in what we 

 may regard as a sterile field — a field in which 

 there are no such bacteria — germination, 

 indeed, takes place, and the plant obtains a 

 start in life, but, having exhausted the 

 nitrogen present in its seed, it dies and there 

 is consequently no crop. In such circum- 

 stances, therefore, it is not only imperative 

 to supply the mineral manures — phosphoric 

 acid, potash, and lime — but also the bacteria. 

 In this case, the seed having germinated, 

 the bacteria assist the young plants to 

 obtain the nitrogen they require, and 

 this, in conjunction with the minerals 

 which have been supplied in artificial 



