AN EXHAUSTING CROP DEFINED. 371 



cess. If the soil be not in good condition, the large amount 

 of readily assimilable food materials they require cannot 

 be obtained, and their growth is proportionably restricted ; 

 if the condition be such as to allow them to satisfy their 

 fullest requirements, by the time they have reached their 

 maturity they will have abstracted so much of the fertilizing 

 materials, as to have considerably reduced its condition, and 

 so far left it in a comparatively exhausted state. These 

 abstracted mineral materials, inert and comparatively use- 

 less in themselves while in the soil, now have been con- 

 verted by the powers of the plant into organized structures, 

 valuable not only as food substances, but also subsequently 

 as manures, fully equal, if they are all consumed on the 

 farm, to replace those abstracted from the soil during the 

 growth of the crop, and to sustain its general state of fer- 

 tility; at any rate, the increased produce thus obtained has 

 always a money value, and that is always more than suf- 

 ficient to pay for any amount of additional manurial sub- 

 stances required to restore the soil to its original condition. 

 As a general rule, we may consider that the crop which 

 in the shortest time can take the most out of the soil, that 

 is to say, convert most mineral substances into food mate- 

 rials, is, cceteris paribus, the most beneficial for cultiva- 

 tion, as it not only increases our powers of production in 

 the first instance, but also in regard to subsequent crops, 

 by the large amount of resulting manure the increased pro- 

 duce has afforded us. Let -the cultivation of the cabbage, 

 then, rest upon its real merits, and not be checked by an 

 erroneous idea about its injuriously exhausting the soil, 

 and thus rendering it less productive for the following 

 crops. There are some disadvantages, it is true, in regard 

 to the labour required in its cultivation ; still there are 

 many circumstances that may greatly outweigh these, and 

 render it both desirable and advantageous to have a cer- 

 tain breadth of them on the farm every year. 



