268 MASS. EXPEKIMENT STATION BULLETIN 171. 



1,092 grams; 1910, 2,440 grams. In two years the crowns and roots had 

 more than doubled in size and weight. 



The average weight of sixteen roots from four plots in each of three 

 years is as follows: 1908, 1,120 grams; 1910, 2,393 grams; 1911, 2,401 

 grams. 



The roots obtained in 1911 actually averaged slightly heavier than those 

 selected the fall before. This may in part be due to the more random 

 choice of samples in the summer before there was sufficient top growth 

 to guide the selection, but is more probably the result of a higher water 

 content in the growing season, as will be seen in the table of composition. 



It has already been mentioned that the first object in collecting the 

 different series of roots was to ascertain the effects of different fertilizers 

 on their composition, but it is deemed best to present first the average 

 composition of the roots at different stages of development, and follow 

 with the composition of other parts of the plant before taking up the 

 specific influences of methods of fertilization. 



In furtherance of the primary object of the investigation, forty-four 

 Cfowns, representing eleven different plots, were collected in the faU of 

 1908; seventy-six from nineteen plots in the fall of 1910; and sixteen 

 from four plots in the summer of 1911. 



A complete analysis was not made of every sample. Nitrogen was 

 determined in every individual sample of each year. Total sugar was 

 determined in about two-thirds of the samples obtained in 1908, and in 

 every sample of the lots of 1910 and 1911. Ash and ash constituents 

 were determined in every sample of the lot of 1908, but only in composite 

 samples representing the individual plots in the series of 1910 and 1911. 

 Dry matter was determined in every sample of 1910 and 1911, but was 

 not calculated in the samples of 1908 because the weights after the first 

 drying were omitted. The other constituents — fiber, pentosans and 

 fat — were determined in selected samples in each series, chosen from 

 some with average percentages of nitrogen or sugars, and others with 

 maximum or minimum proportions. 



In compiling averages for each year from the numerous analyses of 

 individual samples above mentioned there were included only those 

 figures obtained on samples from plots receiving complete fertilizers in 

 some form, and results from plots receiving no nitrogen, no potash or no 

 phosphoric acid were omitted. 



