240 



THE SOUTHERN PLANTER. 



flower-pot, or other suitable vessel, it was 

 observed that the liquid which ran through, 

 no longer contained any of the ammonia 

 or other salt -employed. The soil had in 

 some form or other, retained the alkaline 

 substance while the water in which it pre- 

 viously dissolved passed through. 



Further, this power of the soil was 

 found not to extend lo the whole salt of 

 ammonia or potash, but only to the alkali 

 itself. If, for instance, sulphate of ammo- 

 nia were the compound used in the expe- 

 riments, the ammonia would be removed 

 in clays, a peculiar class of double silicate 

 to which the absorptive properties of soils 

 are due. He found that the double sili- 

 cate of alumina and lime, or soda, whether 

 found naturally in soils or produced artifi- 

 cially, would be decomposed when a salt 

 of ammonia, or potash, &c, was mixed 

 with it, the ammonia or potash taking the 

 place of the lime or soda. 



Prof. Way's " discovery," then, is not 

 that soils have " absorptive properties" — 

 that has been long known — but that they 

 absorb ammonia, potash, phosphoric acid, 

 &c, by virtue of the double silicate of 

 alumina and soda, or lime, &c, which they 

 contain. 



Soils are also found to have the power 

 of absorbing ammonia, or rather carbonate 

 of ammonia, from the air. 



" It has long been known," says Prof. 

 Way, "that soils acquire fertility by ex- 

 posure to the influence of the atmos- 

 phere — Hence one of the uses of fallows. 

 # # I find that clnj' is so greedy of am- 

 monia, that if air, charged with carbonate 

 of ammonia, so as to be highly pungent, is 

 passed through a tube filled with small 

 fragments of dry clay, every particle of the 

 gas is arrested." 



This power of the soil to absorb ammo- 

 nia is also due to the double silicates. 

 But there is this remarkable difference, 

 that either the lime, soda, or potash, sili- 

 cate is capable of removing the ammonia 

 from solution, the lime silicate alone has 

 the power of absorbing it from the air. 



It is on this fact, that the views of Prof. 

 Way, to which our correspondent refers, 

 are based. Lime may act beneficially on 

 many or most soils, by converting the 

 soda silicate into a lime silicate, or in 

 other words, converting a salt that will not 

 absorb carbonate of ammonia from the air, 

 into a salt that has this important proper- 



ty. There is no manure that has been so 

 extensively used and with such general 

 success as lime, and yet " who among us," 

 says Prof. Way, " can say that he perfect- 

 ly understands the mode in which lime 

 acts ?" We are told that lime sweetens 

 the soil, by neutralizing any acid character 

 that it may possess ; that it assists the de- 

 composition of inert organic matters, and 

 therefore increases the supply of vegeta- 

 ble food to plants ; that it decomposes the 

 remains of ancient rocks containing potash, 

 soda, magnesia, &c, occurring in most 

 soils, and that at the same time it liberates 

 silica from these rocks ; and lastly that 

 lime is one of the substances found uni- 

 formly and in considerable quantity in the 

 ashes of plants, that therefore its applica- 

 tion may be beneficial simply as furnish- 

 ing a material indispensable to the sub- 

 tance of a plant. 



These explanations are no doubt good 

 as far as they go, but experience fur- 

 nishes many facts which cannot be ex- 

 plained by any one or all of these supposi- 

 tions. Lime, we all know, does much 

 good on soils abounding in organic matter, 

 and so it frequently does on soils almost 

 destitute of it. It may liberate potash, 

 soda, silica, &c, from clay soils, but the 

 application of potash, soda and silica has 

 little beneficial effect on the soil, and 

 therefore we cannot account for the action 

 of lime on the supposition that it renders 

 the potash, soda, &c, of the soil available 

 to plants. Furthermore, lime effects great 

 good on soils abounding in salts of lime, 

 and therefore it cannot be as a source of 

 lime for the structure of the plant that it 

 operates. 



None of the existing theories, therefore, 

 satisfactorily account for the action of lime. 

 Prof. Way's views are more consistent 

 with the facts of practical experience ; but 

 they are confessedly hypothetical ; and 

 his more recent investigations do not con- 

 firm the idea that lime acts beneficially by 

 converting the soda silicate into the lime 

 silicate. 



Thus, six soils were treated with lime 

 water till they had absorbed from one and 

 a half to two per cent, of their weight of 

 lime. This, supposing the soil to be six 

 inches deep, would be at the rale of about 

 300 bushels of lime per acre. The 

 amount of ammonia in the soil was de- 

 termined in the soil before liming, after 



/ 



f 



