ACTION OF LIME. 185 



earth ; then thoroughly composted with loam spread 

 over the land ; ploughed hi at first only an inch or 

 two, and then deeper, to mix it perfectly. The ap- 

 plication should never be made in wet weather. 



Dr. Dana states that the action of lime on soils 

 is threefold : " First, it is a neutralizer ; second, a 

 decomposer ; third, a converter. 1. There are cer- 

 tain acids which are free in the soil, such as phos- 

 phoric, acetic, or malic, which become neutralized 

 by the lime. 2. There are certain substances which, 

 for want of decomposition, are locked U2), and are 

 therefore useless to plants ; but lime, by forming a 

 combination with them, decomposes and retains 

 them in a state in which they can be easily dis- 

 solved. 3. Lime also acts upon humus, to render 

 it soluble plant-food, by converting it into acid. 

 Therefore, if plants such as sorrel are produced by 

 land, it is evidence that lime is needed to neutralize 

 these free acids in the soil. The more humus a 

 soil contains, the more lime will it need to convert 

 the insoluble matter and undecayed vegetable fibre 

 into decomposed and soluble food. When a great 

 amount of lime is applied, manure must also be 

 added, because the first is not the food itself, but 

 the fuel which prepares it for use. Lime does not 

 revive worn-out land, but gives it the means of 

 using the manure." 



Lime is often applied in a cheap form, as marl. 

 This widely differs in composition ; but that which 

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