190 THE PRINCIPLES OF 



the above rotation may be said to consist in an alternation of 

 fallow or fodder crops with grain crops. 



It is necessary to discriminate carefully between rotations 

 suitable for the two great classes of land known as light and 

 heavy lands. We must not forget that there are many de- 

 scriptions of soils, each of which is specially adapted for certain 

 systems of farming. The two chief classes of soils are, how- 

 ever, heavy or clay soils, and light or free working soils. I have 

 already drawn attention to the entirely different methods in 

 which tillage operations are carried out upon these two classes 

 of soils. In order to understand the principles upon which 

 they are cropped it will be necessary to take them separately, 

 and examine rotations which are found suitable to each. 



Both are cropped alternately with fallow and grain, or 

 fodder and grain, but the kind of fodder crop or grain crop 

 introduced is a point which requires our best attention. 



Taking the case of clay land, the first year of the rotation 

 will be devoted to fallow. If the land is foul, naturally wot, 

 or if the season is late and damp, it is probable that a portion 

 at least will be treated as a bare fallow. If, on the other 

 hand, the land is well drained, clean, and the season be 

 favourable, we shall endeavour to cultivate it for root or 

 fodder crops. We must remember that we are dealing with 

 wheat land, and our root or fodder crops must be selected 

 with a view to following them up with wheat. Thus rape, 

 cabbages, early sown white turnips, early sown swedes, and 

 mangel wurzel may all be appropriately grown on clay soils, 

 as they allow of being consumed in the late summer month 

 when the ground will not suffer either from the treading of 

 sheep or the passage of carts over its surface. Vetches, also, 

 may be grown upon the fallow portion of clay land for 

 summer consumption by sheep, or for soiling at home, but 

 cannot compare with the crops already mentioned for cleaning 

 purposes. If vetches are taken, it will be necessary to half- 



