2 



first crops of grain, does not arise solely from that degree of richness in the soil which produced 

 the superior grasses in such abundance, but rather from the accession of so large a quantity of 

 vegetable matter, which is at once supplied to the land by ploughing m the turf. 



- _ J 



Having met with no 



specific information in any agricultural works within my reach, re- 

 specting the change produced on the nature of rich pasture land by a course of grain crops, I 

 made several experiments to supply the apparent defect. The results of one of these experi. 



ments I may be permitted to detail. - 



A space oftwo square yards of rich ancient pasture land, was dug to the depth of the surface- 

 soil, which was eight inches, and removed to a place more convenient for making the experi- 

 ment, but placed on a subsoil of the same nature as that on which it was before incumLent. 

 Three inches from the bottom of the mass were first placed on the subsoil, and the turf was tlieii 

 reversed on this, to the depth of five inches : this mode was adopted, to place the ground under 



circumstances as similar as possible to that of ploughing it five inches deep, in the usual manner 

 of breaking up pasture land. 



The nature of the soil was now ascertained, by taking up a portion of it to the fall imi\ 



J , 



only rejecting the green living vegetable parts of the turf. ' 



400 grains, freed from moisture and the plants of grass, consisted of 



4^ 



Calcareous and siliceous sand, of different degrees of fineness 



I 



Decomposing vegetable matter, and particles of roots 

 Carbonate of lime, or chalk - -. - , 



Silica, or earth of flint - - - ' - 



Alumina, or pure matter of clay - - ■ - 



Oxide of iron -' - ■ r- 



Soluble vegetable matter, and sulphate of lime, or gypsum 



102 grains 



h H 



DO 



160 



50 



25 



4 



4 



-^ 



The soil was then cropped for five seasons alternately, Avith, 1st, Oats • 2cl Potatoes; 

 Sd, Wheat; 4th, Carrots; and 5th, Wheat— to the end that it might suffer as much as could 

 possibly happen, under ordinary circumstances, by an impoverishing, or injudicious rotation of 

 annual crops. Every trace of the turf was by this time entirely lost in the general mass of the 

 soil, which was now examined, to ascertain what change" it had undergone by these crops. It 

 appeared to consist of 



h 



' h 



Calcareous and siliceous sand, nearly as before 



Decomposing vegetable matter, destructable by fire 



Carbonate of hme, or chalk, nearly as before 



Silica, or earth of flint - - .. 



Alumina, or pure matter of clay 



Oxide of iron 



Soluble vegetable and saline matter : - 



100 grains. 

 48 

 159 



57 

 26 



5 



3 , 



--I 



The above details shew that very little, if anv plif»ino.^ i. j i . . • 



^ ; ... ^ . ■.' ■ ^ ^^^ange, had taken place in the constitution 



or the sou, in respect or its earthv ingredients • hiih ^ . , . i 



^, ^ • , ' ^ "^^^y considerable diminution of its de- 



composing vegetable and animal matters; particularly when it i« . • i i u . nAA\- 



^. T 1 r J , . . 1 7 ^ vvuen It IS considered how erreat an aoai 



tion had been made to the original proportion itcontQiv. ;} r i ^ ^ -l- h 



. A -.1, .1, -I c^^tained of this constituent, by the turf, whidi 



was incorporated with the soil. > J ' 



\ - 



^-^ 



