262 BRITISH PLANTS 



Pasture, on the other hand, is used only for grazing 

 (seep. 20). 



The continual removal of hay from the meadow tends 

 to impoverish the soU, and fresh supplies of plant-food 

 must be added in the form of manure, if profitable crops 

 of hay are to be obtained. The manuring of the ground 

 has a big influence on the growth of all the plants, both 

 grasses and weeds, but in a different way. The grasses 

 grow more luxuriantly, and foria such a dense shade that 

 many of the weeds are kUled outright, whilst others are 

 so injured by the lack of light that the seed produced is 

 poor in quality and small in quantity, and in time these, 

 too, disappear. At the experimental station at Rotham- 

 sted plots of meadow-land have received the same treat- 

 ment for over fifty years, and the influence of manuring is 

 strikingly shown by the relative proportion of grasses and 

 weeds in the hay obtained from each plot. On un- 

 manured ground less than half the hay was graminaceous 

 herbage, over 39 per cent, useless weeds, and the remainder 

 leguminous herbage — -e.g., clover and bird's-foot trefoil, 

 which has a fairly high dietetic value. On well-manured 

 ground over 99 per cent, of the hay consisted of grasses 

 and less than 1 per cent, of weeds. The age of the 

 meadow also is an important factor in determining the 

 abundance and character of the weeds. In temporary 

 meadows, laid down to grass for one year only, a large 

 proportion of the weeds are annuals — relics of the previous 

 year's cultivation ; but in permanent meadows they 

 gradually disappear as time goes on, and in old meadows 

 they are as rare as in the natural pasture. 



The grasses required to produce good hay must be 

 quick-growing, and this can only be when an abundance 

 of water is present in the soil, and the climate is warm and 

 humid. Meadows are consequently chiefly found in 

 valleys and on low-lying ground. On hUl-slopes the con- 

 ditions are unsuited to the rapid growth of the herbage, 

 and the land is laid down as pasture. This artificial 

 pasture forms much better grazing-ground than the 

 natural pasture, for the land is specially prepared, and the 

 grasses are more luxuriant and selected for the purpose 

 in view. The artificial pasture is usually kept for milch- 

 cows, the natural pasture for sheep. » 



The most common grasses selected for laying down 



