4 BULLETIN 1087, U. S. DEPARTMENT OF AGRICULTURE. 
seed. One portion of the plat was harvested 3 times during the sea 
son, another 7 times, and the remaining portion 18 times. The re 
suit of the different treatments on the vitality of the plants was 
shown in the mortality that occurred the following winter. 
(Table 1.) 
The plat harvested 3 times was clipped with a mowing machine, 
while the plats harvested 7 and 18 times during the season were 
clipped with a lawn mower. The harvested material was removed 
from the plats in all cases. 
f 
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Fig. 1. — Alfalfa roots from a plat clipped three times during the second season. 
Table 1. — Effect of frequency of clipping on the vitality of alfalfa plants at 
Redfield, S. Dak., in 1916 and 1917. 
Treatment during the season of 1916. 
Chpped 3 times during season 
Clipped when 6 inches tall, 7 times during season 
Clipped 18 times during season 
Stand (percent). 
1916 
1917 
100 
100 
100 
Mortality, 
winter of 
1916-17 
(per cent). 
17 
92 
98+ 
The data given in Table 1 show that the plants from the plats 
clipped 7 and 18 times were so weakened in vitality by the frequent 
clippings that they suffered almost complete mortality the following 
winter. Although considerable winterkilling occurred in the plat 
harvested three times for hay, a satisfactory stand remained. 
In October, 1916, at the close of the period of treatment, 12 plants 
were removed from each of the plats and the root systems photo- 
graphed. The plants in each case were taken consecutively from 
representative areas. The plants from the plat harvested 3 times 
during the season showed a much larger and stronger root growth 
