— 62 — 
no figures established by experiment—the reason has been 
given elsewhere—I estimate the minimum to be between 
fifteen and twenty percent, of the total dry matter, includ¬ 
ing all the leaves that fall during the growth of the plant 
and the making of the hay. 1 believe twenty per cent, of 
the dry matter to be a reasonable estimate. 1 he amount of 
matter added to the soil in the form of a top dressing on 
this basis of loss is more considerable than at first appears. 
The actual amount ranges from .95 ton for a 3-ton yield of 
hay to one ton for a 5-ton yield. It is not only twenty per 
cent, of the total dry matter, it is about one ton of the rich¬ 
est portion of the crop, equivalent to the addition of 70.4 
pounds of nitrogen and 168.8 pounds of ashes. Some 
of the nitrogen may be lost, but the whole of the ashes is 
avadable. I he table quoted by Prof. Ankman shows that 
the first nine inches of the cropped soils are rich in nitric 
nitrogen, and in the case of the alfalfa they contained more 
than one-half of the total found to the depth of nine feet, 
8.9 pounds out of a total of 17.0 pounds. 
These facts may be more directly related than at first 
appears. The ashes contain seven pounds of phosphoiic 
acid and 28.6 pounds of potash, which have been brought 
up from below. A. portion of this is, doubtlessly, 
taken up by the plant and utilized in making the next year s 
crop ; but there is a remainder each year which accumulates 
to the enrichment of the surface portion of the soil. 1 in- 
accumulation of nitrogen is probably less in Colorado than 
it would be were our conditions more favorable to the for¬ 
mation of humus in the soil. There is no series of analyses 
showing how great the changes in the surface soil are in re¬ 
spect to humus, nitrogen, or ash constituents; we have onl> 
the general results as measured by the increase in wheal 
produced, and this only in general terms. I have presented 
the composition of the plant and its parts; the amount 01 
plant debris added year by year; the stubble added to the 
soil at the end of one, five, and ten years; also the amouni 
of roots not included with the stubble; and I have also inti 
mated another source of addition to the soil during a pari 
of the life of an alfalfa field, i. e., by the perishing of the 
inner portion of the roots. The composition of the plan! 
debris has been given and the following tables contain the 
analyses of stubble and roots and the fixed ash constituent: 
for each thousand pounds of air-dried material:— 
