84 DRY-FARMING 
vif 
downward; though under conditions that are not 
favorable for the downward penetration of the roots 
the lateral extensions may be very large and near the 
surface (Figs. 22, 23). 
Extent of roots 
A number of investigators have attempted to 
determine the weight. of the roots as compared 
with the weight of the plant above ground, but the 
subject, because of its great experimental difficul- 
ties, has not been very accurately explained. Schu- 
macher, experimenting about 1867, found that the 
roots of a well-established field of clover weighed as 
much as the total we ght of the stems and leaves of 
the year’s crop, and that the weight of roots of an 
oat crop was 43 per cent of the total weight of seed 
and straw. Nobbe, a few years later, found in one 
of his experiments that the roots of timothy weighed 
31 per cent of the weight of the hay. Hoseus, 
investigating the same subject about the same time, 
found that the weight of roots of one of the brome 
grasses was as great as the weight of the part above 
ground; of serradella, 77 per cent; of flax, 34 per cent; 
of oats, 14 per cent; of barley, 13 per cent, and of 
peas, 9 per cent. Sanborn, working at the Utah 
Station in 1893, found results very much the same. 
Although these results are not concordant, they 
show that the weight of the roots is considerable, 
