376 



SCIENCE OF AGRICULTURE. 



Part II. 



is in some degree counterbalanced by the circumstance of one such ploughing being 

 mostly sufficient for the crop. It is, says a late theorist, consequently evident that, con- 

 sidering the number of ploughings generally given in the ordinary way of preparing 

 lands for a crop of barley or turnips, and under the fallowing system for wheat, and the 

 labor and expense in the latter case, in raking, picking, and burning weeds, the advan- 

 tages of this plough are probably greater than is generally supposed. It has also advan- 

 tages in another point of view, which is, that the soil is increased in depth, and the parts 

 of it so loosened and broken down that the fibrous roots of the crops strike and extend 

 themselves more readily in it, and of course are better fed and supported. In thin and 

 sandy soils it is more particularly useful, because it cuts off all which is on the surface, 

 at the depth of an inch or an inch and a half, in order to its being laid in a state of decay, 

 for a future crop, by which an increased depth of soil is given to every subsequent course 

 of crops, and which often acts as a support, to keep up manures near the surface, as 

 their running through such soils too quickly is a disadvantage. It is also capable of 

 being made use of without a skim-coulter as a common plough. 



2495, A skim coulter may be added to any other plough, and may be useful in turning down green croi)s 

 and long dung, as well as in trench ploughing. But in most instances it is thought a preferable plan, 

 where the soil is to be stirred to an unusual depth, to make two common swing-ploughs follow each other 

 in the same track ; the one before taking a shallow furrow, and the other going deeper, and throwing up 

 a new furrow upon the former. 



2496. The double share plough is distinguished by having one share fixed directly over 

 the other. It is made use of in some of the southern districts, with advantage in putting 

 in one crop immediately after ploughing down another, as by it a narrow shallow furrow 

 is removed from the surface, and another from below placed upon it, to such depth as 

 may be thought most proper, it being capable of acting to ten inches or more. In this 

 manner many sorts of crops, such as rye and other green crops that have much height of 

 stem, m*ay be turned down without the inconvenience of any of the parts sticking out 

 through the seams of the furrow slices, by which the farmer has a clean surface of mould 

 for the reception of the grain. 



2497. The mining plough, or trenching plough, is sometimes employed for the purpose 

 of loosening the soil to a great depth, without bringing it up to the surface, a mode of 

 operation which is particularly useful for various sorts of tap-rooted plants, as well as 

 for extirpating the roots of such weeds as strike deep into the ground. For these pur- 

 poses it may be employed in the bottom of the furrow after the common plough. It is 

 constructed in a very strong manner, having only a share without any mould-board. 



2498. The douMe furrow plough (^g. 286.), is obviously advantageous in performing 



285 



more labor in a given time with a certain strength of team, than other sorts of ploughs, 

 as producing two furrows at a time. It has been found useful on the lighter sorts of 

 land where the ridges are straight and wide, though some think it more confined in its 

 work than those of tlie single kind. The saving of the labor of one person, and doing 

 nearly double the work with but little more strength in the team, in the same time, re- 

 commend it for those districts where four horse teams are in use. This plough has been 

 brought to its present degree of perfection by Lord Somerville, especially by the intro- 

 duction of the moveable plates already mentioned (2492.), at the extremities of the 

 mould-board, as in his Lordship's single plough. But, as observed by an excellent 

 authority, " witl^ all the improvements made by Lord Somerville, it can never come 

 into competition, for general purposes, with the present single furrow ploughs;" Lord S. 

 admits, that it would be no object to invade the system already established in well-culti- 

 vated counties ; though, where large teams are employed, with a driver l)esides the 

 ploughman, it would certainly be a matter of importance to use this plough, at least, 

 on light friable soils. " Their horses," he says, " will not feel the difference between 

 their own single furrow working one acre, or tlie well constructed two furrow plough, 

 with two acres per day ; here is no system deranged, and double work done." {Com- 

 munications to the Board of Agriculture, vol. ii. p. 418.) 



2499, The Argylcshire plough diilers from Small's, or any single swing [jlough, in 

 having no coulter fixed in the beam, but in liey of this, a fin or knife rising from the left 



