Bee. 6, 1915 
Influence of Growth of Cowpeas on Soil Properties 443 
vidual cores also substantiates the conclusion derived from preliminary 
tests, that a thoroughly mixed composite is an authentic measure of the 
actual nitric nitrogen in the soil. 
Table I. —Relative compactness (number of drops of ram) of soil on the various plots at the 
beginning of the experiment (June ig, 1912) 
Trial No. 
Plot D 
(unplowed; 
clean). 
Plot E 
(unplowed; 
cowpeas). 
Plot F 
(plowed; 
cowpeas). 
Plot G 
(plowed; 
artificial 
shade). 
Plot H 
(plowed; 
clean). 
1. 
17 
8 
3 
2 
3 
22 
7 
6 
3 
3 
3 . 
18 
9 
3 
2 
4 
4. 
12 
8 
3 
4 
3 
5 . 
13 
14 
3 
4 
3 
6. 
12 
12 
3 
3 
2 
7 . 
12 
13 
4 
3 
4 
8. 
10 
11 
6 
3 
2 
9 . 
13 
9 
3 
4 
2 
II 
13 
4 
3 
3 
IO 
15 
3 
4 
2 
12 
10 
3 
3 
3 
13 . 
l6 
9 
6 
5 
1 
14 . 
II 
7 
3 
5 
2 
15 . 
12 
7 
5 
4 
2 
Average. 
13-3 
i°* 5 
3-6 
3-4 
3-6 
Table IX. —Quantity of nitrate as NO z in the soil of all plots (June 24 , 1912) a 
13 S' 
14 C. 
15 C. 
16 c. 
17 c. 
18 c. 
19 c. 
20 C. 
21 c. 
22 C. 
Average... 
Composite 
Final. 
Quantity of nitrate (p. p. m.)— 
First foot. 
Second 
foot. 
Third foot. 
6 . 14 
3*21 
5* n 
<5-93 
6 . 13 
2-37 
6 . 46 
3*5i 
3*27 
7 . 26 
3 * 20 
3 . 66 
12 . 25 
3* 76 
3* 05 
3* 93 
3*25 
4 . 78 
9- 15 
4*05 
2 . 09 
5.86 
3-^9 
4*35 
7-43 
3*37 
2 . 26 
9- 30 
3* 76 
2 . 58 
7.46 
3- 79 
3-35 
8 . 06 
3*$i 
3- 56 
7.76 
3* 80 
3- 45 
Plate Xlyll shows the general plan of the experiment and the thrifti¬ 
ness of the cowpeas at the early date of July 17—about a month after 
planting the cowpeas. 
a The nitrate determinations were made by using the phenoldisulphonic-acid method, as suggested by 
Schreiner, Oswald, and Failyer, George H., in Colorimetric, trubidity, and titration methods used in soil 
investigations. U. S. Dept. Agr. Bur. Soils Bui. 31, p. 39 - 41 . 1906 * 
