126 GRASSES AND FOUAGE PLANTS. 



In regard to the nutritive value, as based on the amount of 

 nitrogen or nitrogenous compounds, it may be remarked that 

 the latest and most careful experiments, conducted by most 

 experienced and competent experimenters, tend to show that 

 this basis is correct, so far as it can be applied to substances so 

 analogous in composition that they can be included in one 

 group ; as for example, the different root crops possess a nutri- 

 tive value in proportion to the amount of nitrogen they contain, 

 but the nutritive value of a root ought not to be compared with 

 a succulent vegetable, like clover, for instance, by the propor- 

 tion of nitrogen in each, merely, without taking into considera- 

 tion other properties. In other words, roots may be compared 

 with each other on that basis merely, and grasses with each 

 other, and leguminous plants with each other, but not root 

 crops and grasses. This fact is alluded to as a possible source 

 of error in some of the earlier researches of Boussingault, and 

 not as materially afTecting the practical value of the table. 



The mode of using table XIII. is very simple. Good upland 

 meadow hay, — or what would be called in New England, good 

 English hay, — is taken as a standard of comparison. Now if 

 we wished to produce the same results with carrots as with 

 one hundred pounds of good, average English hay, we must 

 use, according to Boussingault's column of equivalents, 382 

 pounds of carrots, or for each pound of hay, 3.82 pounds of 

 carrots, and according to the- practical experiments mentioned, 

 366 pounds, 260 pounds, 225 pounds, 300 pounds, and so on, to 

 each 100 pounds of hay. 



According to the theoretical values of Boussingault, 100 

 pounds of hay are equal in feeding qualities to Qb pounds of bar- 

 ley, 60 pounds of oats, 58 pounds of rye, or 55 pounds of wheat. 

 While, according to the experiments of Thaer, 100 pounds of 

 hay produced the same effect as 76 pounds of barley, 86 pounds 

 of oats, 71 pounds of rye, 64 pounds of wheat. 



With regard to the analyses of tables YIL, VIII., IX. and X., 

 some allowance should undouljtedly be made for difference of 

 climate, since it is well known that grasses, as well as other 

 plants, grown rapidly in a hot sun, which we usually have in 

 the months of May, June and July, contain a much larger 

 amount of nutritive and saccharine matter than those grown 

 slower and in a greater amount of available moisture both m 



