A FERTILIZER EXPERIMENT WITH ASPARAGUS. 253 



remain in the field to be harrowed under the following spring as perhaps 

 accounting for the fact that there was no apparent favorable effect of 

 manure as compared with chemicals which could be attributed to a greater 

 supply of humus. There can be no doubt that the practice of harrowing 

 in the tops is fully justified by results, both because of its relation to 

 humus content and the lesser removal from the bed of plant-food con- 

 stituents. 



I would, moreover, call attention to a pecuHarity in the growth of 

 asparagus which I believe to be also an important factor in accounting 

 for the apparent non-beneficial effect of continued use of manure as a 

 source of humus. As is well known, the thick roots and the crowns of 

 asparagus plants serve an important function in the economy of the plant 

 as storage reservoirs for reserve materials which are drawn upon heavUy 

 in the production of the spring shoots which constitute the commercial 

 crop. The root system is a very large one. Some of its peculiarities 

 are clearly shown in Figs. 1 and 2. It will be noticed that there is a very 

 large number of crowded, rather thick roots, and that these roots in the 

 plants which have made only three years' growth — one in the seed bed 

 and two after setting — have already attained a great length, and in the 

 aggregate make up a heavy weight. The photographs from which the 

 illustrations were made were taken by the late Mr. C. W. Prescott from 

 one of the roots dug up for purposes of chemical examination, the results 

 of which are reported in Bulletin No. 171. The roots just referred to 

 were taken up in 1908. Another lot of roots was taken up for chemical 

 examination in 1910, and no photographs were taken of any of the roots 

 taken up at the later date. The different roots show considerable varia- 

 tion in total weight and other characters, but on the average were but 

 little, if any, longer, more numerous or heavier than those shown in the 

 illustration. Among the second lot of roots were found some evidently 

 older roots which were hollow and inactive, having undergone partial 

 decay. The conclusion to be drawn from this observation, strongly 

 supported by analogies afforded by well-known facts concerning the life 

 histories of a large number of other plants, both cultivated and wild, 

 is that the root as a rule serves for storage perhaps only a single year, 

 then becomes inactive, dies and decays in the ground. This is true, for 

 example, of Solomon's seal, false Solomon's seal, sarsaparilla and numerous 

 other plants. An analogy is afforded also by the familiar habit of numer- 

 ous bulbous plants as, for example, the crocus, tulip, hyacinth, gladiolus, 

 etc. There can be no doubt that this constant replacement of older 

 roots by new, the older then decaying, contributed largely to the humus 

 content of the soil, and would seem, therefore, to be a highly important 

 consideration in accounting for the lack of favorable influence of manure 

 on the humus content of asparagus beds. 



