No. 63.] 87 



knowledge of the nature of the action of lime, would have prevented 

 such seeming contradictions. " Lime in excess, forms, from the hu- 

 mus of the soil, an insoluble salt; and may thus, when applied to a 

 soil abounding in salts of lime, or in which it already exists, be produc- 

 tive of injury, whatever may be the vegetable or organic matter of 

 the soil. In this state of excess, lime converts, but at the same time 

 locks up, the humus of the soil; when if applied in the right quantity, 

 it would have been useful. Lime is of no value whatever as a con- 

 verter, or produces no chemical effect in promoting growth, unless 

 there is organic matter in the soil on which it can act. Lime is most 

 efficient when used on soils full of insoluble humus, such as peaty 

 matter or woody fibre, but which, from the abundance of the tannin 

 principle contained, resist the ordinary processes of decomposition." 

 There would seem to be no difficulty, therefore, in determining wheth- 

 er lime can be used on any given soil to profit. Indeed there are, it 

 is believed, none where it would not be useful, except such as are 

 already supplied with this carbonate, or those which are wholly des- 

 titute of vegetable or organic matter. As a general rule, the greater 

 the quantity of humus in a soil, the greater the amount of lime which 

 may be applied with benefit. As long as there is a store of organic 

 matter in the soil, lime, if not in excess, is a valuable manure; but 

 when this is exhausted, the application of lime only increases the ste- 

 rility by destroying such efforts at vegetation as might in time, aid- 

 ed by light and moisture, partially remove the unproductiveness ex- 

 isting. This fact may serve to explain some of the conflicting state- 

 ments that have appeared in the agricultural journals of our country, 

 on the use of lime. Where humus is abundant, the quantity that may 

 be safely used, is very great; on soils already poor, a small portion 

 speedily exhausted the remaining powers of the soil. Lime, from its 

 alkaline qualities, acts in neutralizing whatever free acids exist in 

 soils, whether oxalic, phosphoric, malic, or others. It acts also in 

 decomposing some of the earthy or compound salts formed in the 

 soil, and thus renders the geine held by them, available to the plant; 

 but its great and most important use is in converting the insoluble or- 

 ganic matters existing, into soluble ones, and thus directly furnishing 

 an abundant source of nutriment. Carbonate of lime is sometimes 

 used pounded or broken fine; and in this state, its mechanical value 

 is great in stiff or clay soils. Such soils too, usually abound in acids; 

 and these gradually acting on the lime gravel, its chemical effect is 

 slowly but beneficially apparent. 



