INTRODUCTION. 



^ 



In many instances, where experiments have been made on thfe produce of plants this 

 essential point has been too much disregarded. It is to this only we can look for T s"^"" "^ 

 factory reason to reconcile the discordance of results obtained from experiments made on ^h' 

 same plant by different persons equally eminent for agricultural knowledge. From the^" 

 source, in a great measure, will be found to proceed the difference of opinion respectLHlIe 

 impoverishing effects of different plants to the soil. It is well known that, on certairiih 

 some plants have greater impoverishing effects than on others; and though the preparatiorof 

 the land, and quantity of manure applied, &c. should be the same in two cases, yet a TTific 



difference in the nature of the soils, will give different results as to their nroduol o, l •*^^^' ^ 

 ■ 1 ■ rr- I'i'-'uul.t; anu impove- 



rishing effects. 



The terms adopted to denote different soils, bave been used without due precision 

 rather, the terms have had no definite idea affixed to them. The term loam, for instance ^^ 

 defined by one to be a fat earth, or marl, and by others, a mixture of clay, sand, and calcar 

 earth, without stating the proportions. In general, on referring to books on Agriculture and g17 

 dening, we are directed to a hazel loam, a brown loam, clayey loam, or to a hungry saldy soT 

 bog sod, peat earth, garden mould, &c.; but from the want of proper definitions of these terms' 

 It IS perplexing, or nearly impracticajjle, to determine which kind of soil is me .,.f T l ' 

 exammed above fifty kmds of sod and composts collected, with their local names, in different 

 parts of the country, and, in several instances, soils of the same name were fomid to differ 

 greatly in their natural qualities. ^ 



The method of determining the nature of soils by chemical analysis, has been of late yeirs so 

 much snnplified by Sir Humpf^ry Davy, that it is now in the power of every practical perJon to 

 ascertam with comparative facility, the qualities of any kind of soil, and consequently to describe 

 the same without any risk of being misunderstood, which before this, was absolately un. 

 voidable. / J *- 



All soils consist of sand of various degrees of fineness, and impalpable earthy matter- when 

 therefore, the exact proportions in which these are combined in a soil, are known wi'th their 

 general properties, it shews directly to which class of soils it belongs, whether to 'the loamy 

 clayey, calcareous, sandy, peaty, &c. 



Sir Humphry Davy, in his Elements of Agricultural Chemistry, states the proportion, of 

 sand, and impalpable earthy matter, to which the terms usually adopted should be limited 

 " Ihe term sandy, should never be applied to any soil that does not at least contain seven- 

 eighths of sand ; sandy soils, that effervesce with acids, should be distinguished by the name of 

 calcareous sandy soil, to distinguish them from those that are siliceous. The term clayey, 

 should not be applied fo any land that contains less than one-sixth of impalpable earthy matter' 

 not considerably effervescing with acids ; the word loam, should be limited to soils containing 

 at least one-third of impalpable earthy matter. A soil to be considered as peaty, ought -to con- 

 tarn at least one-half of vegetable matter."~-These may be considered as the generic characters 

 o soils, and determined by a very simple process, that of washing the impalpable earthy mat- 

 ter of the sod from the sandy portion, and by drying and ascertaining their respective weights, 

 w en the application of an acid, shews whether it belongs to the calcareous or siliceous kinds of 



e results of all my observations, in these experiments on grasses, and likewise in the cul- 



soil. 



Th 



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