134 TILLAGEMOVEMENTS OF SOIL WATER [ch. iv 



bushels more than on plot 7, but in the dry year its 

 superiority amounted to 14 bushels, whereas in the 

 very wet year the two plots sank to the same low level. 

 In a bad season the bacterial changes which render the 

 plant food in dung available for the crop go on very 

 slowly. 



