ON MANURES. 59 



in preventing- it from choking- the instrument, thus occasioning 

 a great increase of draught to the cattle, as well as of labour 

 to the ploughman, rendering the land foul, and defeating one 

 of the main objects of good husbandry. It is also, by some 

 farmers, thought expedient to bury fresh dung so deep below 

 the soil as to allow it to ferment there without being disturbed 

 by the harrows, or even by the shallow ploughing of successive 

 tillage; but, independently of the objection which has been 

 already raised against that practice, it is notj in any such case, 

 found easy to make clean work. 



Many attempts have been made to correct this fault, and 

 considerable improvement has been effected in the construc- 

 tion of ploughs, particularly by the Scotch, some of whose iron 

 swing ploughs have gone far towards a remedy of the defect. 



As relating to the quantity o'l farm-yard dung necessary 

 for raising a course of crops upon arable land of various soils, 

 and under different systems of cultivation, with the proportion 

 which they are capable of producing ; this it is an object of 

 primary importance to ascertain, as precisely as possible. 

 Assuming some admitted facts as data upon which to ground 

 our opinion of the quantity of putrescent manure which may 

 be generally sufficient for an acre, we nearly agree in the 

 opinion expressed by Doctor Coventry, and collected from many 

 other accounts, that from four to five tons are yearly requisite 

 of that kind commonly prepared, and in its usual state of 

 decomposition, as spit-dung. According to that calculation, it 

 must also be observed that the course of crops is supposed to 

 consist — on light soils, of the alternate plan of corn and green 

 crops, — on clays which do not admit of that system, that the 

 holding contain a proportionate quantity of grass-land ; and 

 that the quantity of manure should be supplied, not in small 

 quantities annually, but in large ones, at intermediate dis- 

 tances of four, five, or six years. Light soils, in the common 

 course of husbandry, rarely require the application of putres- 

 cent manure oftener than once in four years, and in all cases 

 where the clover is allowed to stand during two seasons, it 

 may be deferred without disadvantage for another year. 

 Heavy soils may run six years without it, provided that the 

 land be laid one year in fallow, and that there be sufficient 

 meadow to be reckoned at least as one crop in the course. It 

 being, however, clearly understood, that — whether on light or 

 heavy land — nothing but grain, seeds, and live stock is to be 

 sold off the farm, unless replaced witJi an equal portion of 

 f2 



