NUTRITIVE VALUE. 113 



NUTRITIVE VALUE OF THE GRASSES. 



Wc have scGu that the various species of grass differ very 

 materially in nutritive value ; that some contain the greatest 

 quantity of nutritive matter when green or in the flower ; others 

 when the seed is ripe and the plant mature ; that some yield a 

 luxuriant aftermath, while others can scarcely be said to pro- 

 duce any at all ; that some flourish m elevated situations and 

 are best suited to the grazing of sheep, while others grow most 

 luxuriantly on the low lands and in the marshes, and sustain 

 the richest dairips ; and that no soil is so sterile, no plain so barren 

 but that a grass can be found adapted to it. Some varieties, 

 indeed, will not endure a soil even of medium fertility, nor the 

 application of any stimulating manure, but cling with astonish- 

 ing tenacity to the drifting sands, while others prefer the 

 heavieet clays or revel in the hot beds of ammonia; some are 

 gi'cgarious in their habits, requiring to be sown with other 

 species, and if sown alone will linger along till the wild grasses 

 spring up to their support ; others are solitary, and if mixed 

 with different species will either extirpate them, usurping to 

 tliemselves the entire soil, or die and disappear. Nearly every 

 species is distinguished for some peculiar quality, and most are 

 deficient in some, comparatively few combining all the qualities 

 desired by us in alternate field crops, for pastures or permanent 

 mowing, to such an extent as to justify a general cultivation. 



It is important, therefore, to learn the comparative nutritive 

 value of each species thought to be worth cultivating. 



This study is naturally attended with great difficulties. It is 

 but recently that accurate researches have been made with a 

 view of arriving at such positive results as would be entitled 

 to full coniidence.* 



It is now very well established that the nutritive value of the 

 food of an animal depends chiefly upon the proportion of nitro- 

 genous substances contained in it. Without doubt, the sugar 



* In 182 1, a very laudable attempt was made in England by the Duke of 

 Bedford, at Woburn Abbey, to ascertain the comparative value of most of the 

 grasses which could then be obtained, and the results of the experiments, 

 15 



