— 6o — 
acre, is left below the assumed depth of six and one-half 
inches. 
MANURIAL VALUE OF THE ROOTS. 
The manurial value of this portion is not equal pound 
for pound to the stubble, still it is by no means a negli¬ 
gible quantity. The nitrogen is equal to 14.98, practically 
15 pounds per ton of 2,000 pounds; the phosphoric acid 
4.45 pounds, and the potash 14.25 pounds ; or stated differ¬ 
ently, there is less than one-half as much nitrogen, one- 
half as much phosphoric acid, and about the same amount 
of potash in the roots as in the stubble, the first six 
inches of the roots being taken with it. On the other 
hand, while there is 2.86 tons of air-dried matter in the 
stubble, there is 5.14 tons in the rest of the roots, making 
them about equal to the stubble in the total nitrogen and 
phosphoric acid contained,and twice as rich in potash; or ex¬ 
pressed in dollars and cents, the value of the roots below 
six and one-half inches, and to an average depth of ten 
feet, is phosphoric acid, $1.14; potash, $3.84, and nitrogen 
$11.60, a total of $16.58 against $19.32 for the stubble, mak¬ 
ing a total value per acre for the portion left after re¬ 
moving all the crop above ground of $35-9°- I n estimat¬ 
ing this value all the other constituents .of the ash and 
the organic matter have no value signed to them ; 
whereas we know that the organic matter, par¬ 
ticularly for our soils, has a comparatively high value : 
and the other ash constituents presumably in a more fa¬ 
vorable condition for absorption by other plants than the> 
are in the soil, can not be indifferent, though ir is nol 
usual to place any value upon them. 
It may be questioned whether a large portion of the 
plant food stored in these roots does not lie so deep that il 
is beyond the reach of ordinary crops., such as potatoes 
and wheat. Whatever the answer of this question may be 
it is a well attested fact, that the yield of wheat on alfalfa 
ground is often doubled and always greatly increased ; anc 
while the alfalfa is an exceptionally deep-rooting plant, nc 
violence is done to observe facts in assuming that the roots 
of the wheat stimulated by the presence of plant food ir 
certain channels left open by the decaying of the alfalfc 
roots, may penetrate to greater depths than they do wher 
the food is disseminated evenly through the soil. 1 he 
roots,of the wheat plant, however, have been observed tc 
penetrate to the depth of seven feet—Schubart cited b3 
Johnson, “ How Crops Grow,” page 264—which is as deep 
as a large percentage of the alfalfa roots penetrate into 
our soils. 
