294 CAUSES OF FERTILITY AND STERILITY [chap. 



when it has become dissolved as bi-carbonate in the 

 soil water. 



Amendments of the Soil. 



Many soils, without being absolutely sterile, carry 

 very poor crops until their physical character has been 

 altered by the admixture of some considerable quantity 

 of one or other of the constituents of a normal soil 

 that may happen to be originally wanting. These 

 amendments of the soil by the mixture of other soils 

 date from the time that enclosures first began to be 

 made ; they were perhaps at their height during the 

 early years of the nineteenth century, after the middle 

 of which they rapidly diminished as it began to be 

 less and less remunerative to "make" land, until at 

 the present time the fall in the prices of produce and 

 the rise in the cost of labour have put an end to all 

 such operations. Among other causes of this neglect 

 may perhaps be set down the increased use of artificial 

 manures ; men began to take too exclusively a chemical 

 view of the functions of the soil, and shirked expendi- 

 ture which did not seem to add directly any food for 

 the plant. However, it is probable that with modern 

 facilities for moving earth on a large scale by steam 

 power, the improvement of much poor land might even 

 now be profitably undertaken. 



The operations which may be grouped under the 

 head of "amendments of the soil," comprise drainage, 

 which has been dealt with elsewhere ; the marling and 

 claying of light sands ; the reclamation of peat bogs ; 

 the improvement of clay soils by liming and chalking, 

 or by paring and burning ; and lastly, the creation of 

 new alluvial soils by warping. 



