BULLETIN 1087, U. S, 



DEPARTMENT OF AGEICULTUEE. 



seed. One joortion of the plat was harvested 3 times durino: the sea- 

 son, another 7 times, and the remaining portion 18 times. The re- 

 sult 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. 



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. 



Stand (per cent). 



1916 1917 



Mortality, 



winter or 



1916-17 



(per cent). 



CUpped 3 times during season 



CUpped when 6 inches tall, 7 times during season 

 Clipped 18 times during season 



100 

 100 

 100 



1+ 



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 



