82 



Observer, No. 12. 



Vol. II. 



These reflections were occasoned by read- 

 ing an interesting paper, in the 25th number 

 of the Cabinet, by William Partridge, re- 

 commending the use of ground limestone 

 instead of lime, as a manure. 



The theory on which the recommendation 

 rests is simply this, that lime applied to 

 land, must first be converted back to its for- 

 mer state (carbonate of lime or limestone,) 

 before it can promote vegetation. Assum- 

 ing the truth of this theory, he draws the 

 inference, that it would be "a far better 

 general application, that the limestone be 

 merely ground, and in that state, applied to 

 the land." He, however, says, " there are 

 some exceptions to this rule. When a soil 

 contains hard roots, dry fibres, or other inert 

 vegetable matter, a strong decomposing ac- 

 tion will take place between burned lime 

 and the vegetable matter, rendering that 

 which was before comparatively inert, nutri- 

 tious." Now I would suggest, whether the 

 writer may not, by an unhappy transposition, 

 have put the rule for the exception, and the 

 exception for the rule. There are, probably, 

 few soils which do not contain "compa- 

 ratively inert vegetable matter." Those 

 which do not, 1 would consider desperately 

 bad and hopelessly irreclaimable by lime in 

 any form, without the aid of vegetable ma- 

 nure. The great difference between soil and 

 subsoil appears to be, that the former con- 

 tains more vegetable matter than the latter. 

 "For stiff heavy soils, he advises to use 

 the limestone coarsely powdered, for in this 

 state it would so lighten them, as to enable 

 the sun and air to penetrate to their vegeta- 

 tion, thereby rendering the future crops more 

 productive." This will readily be allowed, 

 but the effect would seem to be purely of a 

 mechanical nature, and would be effected, 

 perhaps, as well by the use of silicious sand 

 as that of limestone. I have had some ex- 

 perience and opportunities for considerable 

 observation in this matter, and my opinion 

 is,*that the principal, if not the entire effect 

 produced by limestone in the form of sand, 

 depends on its rendering the soil lighter. 

 In the section of country where I have re- 

 sided, it unfortunately happens, that much 

 of the limestone rock is already disintegrated, 

 or in the form of limestone sand. This has 

 to be removed in order to obtain the hard 

 limestone, which lies underneath. In doing 

 which, it is frequently deposited in large 

 quantities, on the adjacent fields, affording 

 an admirable opportunity of testing the value 

 of coarse ground limestone as a manure. 

 On " stiff heavy soils," it is certainly found 

 to be beneficial as any other sand or gravel 

 would be ; but after having assisted in ap- 

 plying some hundreds of loads in this way, 

 I am free to declare, that I never could per- 



ceive any other effect from it, except in one 

 instance. A few loads of the sands w6re 

 carelessly spread on a lot prepared for buck- 

 wheat, the growth of which was rendered 

 much more vigorous on the parts where the 

 sand had been applied. No effect was ob- 

 servable in succeeding crops. 



If pulverized limestone does possess the 

 value attributed to it, it is quite time the fact 

 should be known. Thousands of loads of 

 it could be obtained in my neighborhood, 

 with the thanks of the owner for taking it 

 away. 



The theoretical opinion, that lime must 

 first be restored to the state of a carbonate, 

 when mixed with the soil, and that its " fer- 

 tilizing property depends (as in plaster,) 

 mainly, if not altogether, on its power to 

 attract moisture during the night, and to im- 

 part it gradually to the plants during the 

 day," is not yet sufficiently proved. I am 

 not aware that limestone sand possesses any 

 greater attraction for water, than silicious or 

 other sands. But admit the fact, and how 

 does it operate ? Does its attraction cease 

 during the day, to allow it to impart the 

 water to the plants ? If it does not, the 

 plants would realise little benefit from its 

 " hydratic property." Admit this also, and 

 from whence does it derive the water during 

 the night? Being buried in the soil it can only 

 derive it from the soil at night, to return it 

 again during the day. The benefit would, 

 therefore, seem to be more fanciful than real. 

 Theory may assist us to devise, and sci- 

 ence may enable us to execute experiments 

 more successfully, but until we ascertain the 

 laws which regulate the nutrition and growth 

 I of plants, we must rely, mainly, upon the 

 data which experiesce affords, to lead us to 

 safe and positive conclusions. As yet, we 

 know too little of what constitutes the food 

 of plants — of their power of converting it 

 into nourishment — and of the combinations 

 of which they are capable of forming. We 

 know too little of the manner in which ma- 

 nures operate, whether nutricions or stimu- 

 lant; and of the modifying influence of soils, 

 seasons and climates, to trust to any theory 

 which does not rest on experience. Agri- 

 culture requires more facts to place it on the 

 sure foundation of a rational and inductive 

 science. 



The facts given by Partridge do not appear 

 sufficient to sustain his position — or "to rec- 

 tify a material error, committed by farmers in 

 using burned lime, instead of ground lime- 

 stone, on their land." He says, " it is well 

 known to every intelligent agriculturist, that 

 soils covering limestone rocks, are the most 

 productiveof any on the globe." Were we to 

 admit this sweeping declaration, to the full 

 extent of its literal import, it would not prove 



