60 THE BOOK OF NATURE STUDY 



of manures on the composition of the herbage. The effect of 

 changing to mineral manure from ammonium salts was to increase 

 the percentage of leguminous plants to 35 per cent., to lessen 

 the weeds by 20 per cent, and the grasses by about 15 per cent. 

 A change from nitrogenous to mineral manure without potash 

 reduced the leguminous plants from about 20 to 5 per cent. 



One practical conclusion that has been drawn from these 

 experiments on grassland is, " that it is better to lay up the same 

 land for hay each year, grazing the aftermath only, and in the 

 same way always to graze other land, rather than graze and hay 

 in alternate years." This is an important conclusion, which 

 should be more widely known than it apparently is, for in many 

 parts of the country it is usual to use the same meadow for mowing 

 and pasture in alternate years. The Rothamsted experiments 

 also show that " land which is growing hay requires a manure 

 which is mainly nitrogenous, whilst pasture requires a mineral 

 manuring." (Rothamsted Experiments, by A. D. Hall.) 



WEEDS COMMON IN MEADOWS. Some of the more common 

 weeds in meadows are : the Common Bent Grass, the Yorkshire 

 Fog, the Quaking Grass, Clovers, the Bird's-foot Trefoil, Burnet, 

 the Beaked Parsley, the Ribwort Plantain, Yarrow, Sorrel, and 

 many others. The Common Bent Grass (Agrostis vulgaris] is 

 characteristic of poor land ; it has thin dry leaves, rough on both 

 sides, and the sheath is colourless. The Yorkshire Fog (Holcus 

 lanatus) is a perennial, with an upright woody stem ; it is a widely 

 distributed weed. The Black Knapweed, or Hardheads, is easily 

 recognised by the bracts of the involucre, which are brown, or 

 black, and deeply fringed. The outer florets are purple, and 

 without stamens or ovules. The Yarrow is also a Composite, 

 with about five or six ray florets, generally white or pink, and 

 with yellow disc florets. The plant has very finely divided leaves. 

 The Sorrel is a dock-like plant ; in poor pastures, where it is often 

 abundant, it forms a sheet of red. The Beaked Parsley (Anthriscus 

 sylvestris) is an umbelliferous plant with umbels of small white 

 flowers. The Salad Burnet (Poterium Sanguisorba) belongs to the 

 Rosacese. It is one of the few genera without petals. Each 

 head contains both staminate and pistillate flowers ; the former 



