358 Transactions of the American Institute. 



results, It must vary with the character of the soil, aud the kind 

 of crop, and a consideration of all these would extend this 

 paper far beyond due limits. To turn now to the remaining 

 subdivision of our subject, we i\iay speak briefly of the mineral ferti- 

 lizers ; and although this may be said to include many different 

 substances which, like nitrate of soda and sulphate of magnesia, have 

 been used on a small or moderate scale with good results, and othei-s 

 more widely used, like gypsum and the like, it must here suifice to 

 consider only the two most important substances belonging to the 

 class : Lime and potash. The first of these, in the great majority of 

 cases, can scarcely be termed a manure, inasmuch as most plants, 

 especially the cereals, contain but a comparatively small portion of 

 lime, and the great majority of soils possess a sufficient proportion of 

 this mineral to supply the wants of the crops grown upon them. 

 There are, however, a few plants which require lime in comparatively 

 great proportions in the soil, as for instance in the leguminous plants, 

 peas, beans, etc. Lime in these often constituting thirty per cent of 

 their ash, it may sometimes occur that these crops are planted on soils 

 which do not contain the requisite quantity of lime ; and the latter 

 when applied thereto might be classed as a manure, inasmuch as in 

 such instances it would contribute directly to the sustenance of the 

 plant. In these cases the lime may be applied in the simple state of 

 the slacked carbonate, or, what is l^etter, in the form of gypsum, which 

 is supposed to possess, in addition to its power of contributing lime to 

 the plant, the valuable property of absorbing or fixing ammonia, 

 which accounts for its great efficiency when applied as a top dressing 

 for clover. Aside from its exceptional action in thus aiding the 

 nutrition of vegetation, the action of lime in ameliorating the con- 

 dition of the soil is both chemical and mechanical ; chemical in 

 breaking down and reducing to othei* forms and combinations the 

 elements of the soil, and mechanical in changing tlieir texture. Lime 

 has been used in English husbandry for more than a hundred years, 

 and in some parts of Great . Britain it has been the ])ractice to 

 lime the land once in twelve years, at the rate of from 120 to 

 200 bushels per acre ; but it is found much better to apply smaller 

 quantities at shorter intervals, and in this country, as in Eng- 

 land, its use will be found most profitable upon wet and boggy 

 land, upon that recently drained, and upon the low alluvial flats bj 

 streams and .rivers. The reason of its great efficiency in these cases 

 may be thus explained. All soils of the character indicated contain 



