62 AGRICULTURE. [cH. 



table growth, you will conclude that this is not a case 

 for the use of caustic lime, because lime in that form 

 will exhaust the organic matter present, and there is 

 evidently none to spare. In such a case, it is there- 

 fore more than probable that its use in the form of 

 chalk or marl, will not only give the required supply 

 of lime, but it will give greater firmness and power to 

 the soil. Caustic lime would probably do more harm 

 than good, whilst in the milder form of chalk or marl 

 it would be highly beneficial. 



1 20. As another illustrative case, we will take a 

 strong clay soil; here it is more than probable that the 

 preference would be given to the use of caustic 

 lime, because of its more perfect action upon the inor- 

 ganic matter. It is, however, quite possible that the 

 use of chalk might be less expensive, and although a 

 less desirable form of lime, it might be chosen for this 

 reason. Yet, even in such a case it must be remem- 

 bered that the influence of the chalk upon the clay 

 would have been very much increased if it had been 

 burnt. 



121. As a general rule, it may be taken that caustic 

 lime should not be used if there is a scarcity of vege- 

 table matter in the soil, and if it be light, and porous ; 

 but if there be a large quantity of organic matter, or if 

 the soil be heavy and tenacious, then lime ought to be 

 used in the caustic form. If you once understand the 

 special action of lime in the two conditions of caustic 

 and carbonate, you will have little difficulty in deter- 

 mining which is the more desirable form. It must, 

 however, be remembered, that the varying circum- 

 stances and conditions of soil, climate, and the system 

 of husbandry, call for judgment and local experience. 

 For the present, at any rate, science must be, to a 

 great extent, limited to an explanation of successful 

 practice; and when an apparent conflict arises be- 

 tween them, science must be content to indicate the 

 truth, without claiming for itself any certainty as to 



