10 
S. DEPAPxTMEXT OF AGRICULTURE. 
number of plants of the same alfalfas. The roots taken in October, 
1916, and May, 1917, were from the central portion of 8-rod rows; 
the roots taken in August, 1919, were from the north ends of the rows 
and those taken in October, 1919, were from the south ends. Data, 
unless otherwise stated, were obtained on the first 18 inches of root. 
This portion of the work was concluded in 1919. It was later found 
desirable to include data comparing southern-grown common and 
Grimm with plants of the same age of the prostrate and decumbent 
forms of pure Medicago falcata. In the fall of 1920, after grow- 
ing six seasons, plants were removed from the nursery. No appar- 
ent mortality had occurred among the yellow-flowered plants from 
the time they were planted in May, 1915, to September, 1920. Only 
a 5 per cent mortality occurred in the Grimm variety, although some 
of the surviving plants showed winter injury. In the southern- 
grown common, 40 per cent of the plants had been killed or very 
seriously injured. All plants of Medicago falcata had pure yellow 
flowers and there were no evidences of hybridization. 
CONDITIONS UNDER WHICH VARIETIES WERE GROWN. 
Root studies were conducted from 1916 to 1919 upon varieties of 
alfalfa sown May 24, 1916, in drilled rows 36 inches apart and under 
similar soil conditions. The alfalfas studied in September, 1920. 
were . sown in 42-inch rows in May, 1915. The only treatment to 
which these rows were subjected was clean cultivation throughout 
the season and the burning off of the dead stems in the early spring. 
The soil is fertile, well drained, and well supplied with organic 
matter and nitrogen-fixing organisms. In order to determine the 
character of the soil, a trench was opened in the alfalfa nursery in 
October, 1916, and samples taken at various depths and sent to the 
Bureau of Soils, United States Department of Agriculture, where 
a mechanical analysis and determination of calcium carbonate were 
made. The results obtained are shown in Table 3. 
Table 3. — Mechanical analyses and determination of calcium carhonatc in rep- 
resentative soils at the Redfield Field Station, 8. Dak. 
Description. 
Constituents (per cent). 
Depth from 
which soil 
sample was 
taken. 1 
Lime 
(CaC0 3 ). 
Fine 
gravel, 
2tol 
mm. 
Coarse 
sand, 
1 to 0.5 
mm. 
Medium 
sand, 
0.5 to 
0.25 
mm. 
Fine 
sand, 
0.25 to 
0.10 
mm. 
Very 
fine 
sand, 
0.10 to 
0.05 
mm. 
Silt, 
0.05 to 
0.005 
mm. 
Clay, 
0.005 
to 
mm. 
to 1 foot 
1 to 4 feet 
4 t© 5 feet 
Silly clay loam... 
Clay.....' 
0. 25 
13.63 
11.45 
6.97 
6.31 


.9 


0.3 
.1 
1.0 


0.4 

.4 


11.6 
1.1 
1.0 
.2 
1.2 
13.1 
1.9 
2.2 
.3 
1.0 
52.1 
24.7 
81.4 
33.5 
21.6 
22.1 
72.2 
13.2 
5 to 8 feet 
8 to 10 feet 
Clay 
do 
66.0 
76.1 
Samples, as listed in the table, are averages for the depths stated. 
