MANUAL OF AGlilCULTUrvE. 273 



Of common perennial and Italian Bycgrass tlie analyses are — 



Lolium percnne. Lolium Italicum. 



Water, 71-43 75 -(Jl 



Nitrogenous compounds, . ' 3'37 2'45 



Oleaginous and respirators, . 12 "99 14-91 



Fibre, . . . " . . 10-0(i 4 82 



Ash, 2-15 221 



And of the ash of 



Lolium perenne. 



In flower. lu seed. As hay. 



Potash 12-45 10-77 8-03 



Soda, .... 3-98 "13 2-17 



Lime, .... 9'95 12-29 6-50 



Magnesia, .... 2-23 2 64 4*01 



Peroxide of iron, . . '78 "30 "36 



Phosphoric acid, . . 6-04 6-32 12-51 



Sulphuric acid, . . . 2'82 1-31 



Silica, .... 59-18 60-62 64-57 



Chloride of sodium, . . 2-27 5-58 



By conversion into hay, grasses and clovers lose about three- 

 fourths of their weisjht of water. 



AVhatever may be considered the necessity of rotations as a 

 preserver of the due balance of the soil's constituents, they at all 

 events afford facilities for the periodical cleansing of the ground 

 from the weeds, which at a subsequent period of any rotation 

 might flourish in a particular crop, the nature of wdiich might 

 precUide any such purification ; as in the case of grain crops, for 

 instance, sown broadcast or too closely drilled to admit of the 

 intervening soil being hoed. The crops in a rotation which 

 •allow of a thorouGjh cleansinj? from weeds being eii'ected are 

 turnips and the like, mangolds, potatoes, and so on. As these 

 several crops are drilled at a sufficient distance apart to permit 

 the passage of horse hoes between the rows, the soil can be 

 thoroughly kept free from weeds till the possibility of their 

 flourishing is taken away by the growth of the crops to such a 

 point as to effectually protect and shade the intermediate spaces 

 from free air and light. The crops last-mentioned, together with 

 grasses and other forage plants cultivated for the sake of their 

 roots or leaves, pass by the name of green crops. The grain 

 -crops, on tlie other hand, or those cultivated for their seeds, are 

 called white crops, corn crops, or cereals. 



Formerly it was a prevalent custom at stated intervals to leave 

 portions of ground uncropped for a whole season, repeated 

 pluugliing and oilier workings being granted to it during the 

 summer, in order to destroy the weeds as far as possible. This 

 was called giving the land a bare or nakud fallow. This practice- 

 is still had on strong soils, but it is gradually yielding to that of 

 taking out of the soil some green fallowing crops, ejj., cabbage, 

 which is well suited to strong soils. AVheat and beans in suc- 

 cession, vritli an occasional bare fallow is an example of a two • 



Si 



