TO BE AacnmRED by EXPKBIENCE. OT 



land. After cultivating one grain crop for a very 

 lengthened period in a rotation, it will be found of 

 advantage to make an occasional change to some 

 other. The land appears to grow tired of a crop after 

 a time, and to do better with another even of the same 

 class. There are some districts in Scotland, where 

 clover was for more than a century ' n five 



years, their rotations in those distn ^, over 



that ii^>ace of time ; now they can only get it once in 

 ten years, or every other rotation, and that not so good 

 ai formerly : they call such land clover-sick. Instances 

 of this character show very strongly the value of rota- 

 tion in cropping, and establish by facts the theoretical 

 view that bas Deea taken of the advantages likely to 

 result from such a system of cultivation. As we come 

 to know more of the composition of our various crops, 

 of the soils, and of manures, we may expect to attain 

 greater exactness in our calculations of the amount 

 taken off during any single year, or during an entire 

 rotation. 



In each district, the farmer, by careful obiervaliOB 

 aad study, can after a time mark out the ifilcai of 

 oropping end of manuring best adapted to his particu- 

 lar soil and localitv. 



1. If he knows the character of the rock from wback 

 his soil was originally fonncd, his task is comparative- 

 ly easy ; for from the known composition of the rock, 

 he can come very near that of the soil. 



2. If he has no knowledc^eof this kind, he can still 

 hope to arrive at goo<l results, by d»Hluc«i<>rts from the 

 known character of the crops that have Ufn chiefly 

 cultivated upon his farm. He can tell what are the 

 substances that have been most probably exhausted by 

 these crops, and experiment accordingly with manures 

 in which those are the chief conrtituenta. 



3. A still more satisfactory wav>wouki betoproonrf 

 good analyses of sotb hy reelry rompetcnt 



