MINERAL NUTRITION 163 



These figures confirm what is ah'eady known with respect to the variation in 

 the ash content after the corn plant matures; namely, that with the exception of 

 the phosphorus, all the ash constituents diminish relatively as the plant approaches 

 maturity. The phosphorus remains constant or nearly so because the tendency 

 to diminish, which is characteristic of the other constituents of the ash, is offset 

 by the fact that the seed contains a much higher percentage of phosphorus than 

 do the other parts of the plant. 



Mineral Matter in Miscellaneous Roughages and Concentrates 



In addition to the mineral analyses of roughages collected in various sections of 

 Massachusetts, numerous mineral analyses have been made of different roughages 

 and concentrates used in connection with our experiments in mineral nutrition 

 during the last few years. Most of the roughages were grown upon the experi- 

 ment station and college farm or on farms near by. The concentrates came from 

 different sections of the country. Those marked "Feed Control" were collected 

 in this State by the station inspection service. In addition, for the sake of com- 

 parison, other sources were drawn upon. Those marked "M. and L." refer to 

 Mentzel and Lengerke, the German tabulation, and those marked "Forbes'' 

 were taken from Bulletin 255 of the Ohio Experiment Station and were made 

 under the direction of E. B. Forbes. 



The percentages of only the most important mineral elements are presented, 

 namely, calcium, phosphorus, magnesium, potassium and sulfur. Silica, while 

 not stated, was found in amounts varying from one to two or more per cent in 

 roughages and grain hulls and less than one per cent in most concentrates. Iron 

 and aluminum were present in quite small amounts as well as traces of sodium. 

 The legume roughage contains the most calcium, followed bj' the non-legumes, 

 while not much more than .1 to .2 per cent is to be found in the concentrates; 

 the latter, on the other hand, contain considerable amounts of phosphorus. The 

 roughages contain liberal amoimts of potassium, and most concentrates contain 

 fair to liberal quantities. Both roughages and concentrates have reasonable 

 amounts of magnesium, although the amount of this element varies considerably 

 in different plants, grains and by-products. 



The variations in the percentages given by the different authorities as a rule 

 are not marked. Bj'-products are likely to vary in composition to a limited extent. 

 In general it may be said that the roughages furnish most of the calcium and the 

 concentrates most of the phosphorus. 



