108 AGRICULTURAL BACTERIOLOGY. 



away from the soil by the rain water which easily washes 

 through such fallow land. At the end of the fallow year the 

 land may thus have actually less nitrogen than at the start. 

 The nitrates have probably been removed more rapidly than 

 they would have been if the soil had been cultivated. Nitri- 

 fication has been checked, no crops have been produced and 

 the whole year is thus worse than lost. One of the factors of 

 a continued soil fertility is a continued soil cultivation conducted 

 under proper conditions. 



