IOWA ACADEMY OP SCIENCE 
121 
The problem was attacked from another side by using an entirely different 
medium in which to grow the clover. Quartz sand was used. This was ab- 
solutely neutral and non-toxic. With it as a substratum, eliminating the factor 
of the soil, the action of the manure was seen directly, and it was not com- 
plicated by appearing in connection with the action of the soil. 
For this experiment a medium grade of quartz sand was used. The sand 
was prepared by placing it in pots with drainage outlets, digesting it with a 
10 per cent solution of sulfuric acid, and washing the acid out with tap water 
until the sand was neutral in reaction. The tap water was then washed out with 
distilled water and the sand dried. It was dried in order that the net weight of 
the sand going into the pots could he known, and the pots be kept at the opti- 
mum water content. Gallon pots were used with the outlets stopped. 4,700 
grams of the dry sand were placed in each pot. One gram of c.p. calcium 
carbonate was added to the sand in each pot to prevent any possible acidity. 
Enough distilled water was added to bring the sand to 15 per cent water con- 
tent, as this seemed to be its optimum. Distilled water was used throughout 
in Vv^atering the series. By weighing at any time the per cent of water in the 
sand could be known and water added to supply the evaporation. 
The nutrient solution used was the standard one used in the laboratories of 
the Iowa State College. The following comparisons shows the elements of 
fertility found in it and in the sample of manure leachings with which it is 
compared. 
Element's 
Nutrient solution, g. per L 
Manure leachings, g. per L 
N 
11.2 
.470 
P 
2 . 
.093 
K 
2 . 
1.080 
Five c. c. of the nutrient solution was used per pot on those treated with 
mine^’ai plant food. 117.5 c. c. of the manure leachings were applied to each 
pot treated with manure. This amount of leachings contained the same amount 
of N and P as 5 c. c. of the nutrient solution, but considerably more K. The 
series was planted July 25, 1907, and the clover sprouted uniformly and grew 
off without any check. 
The treatment of the series is shown in the following table which also gives 
the notes taken on September 6th, and the final weights and notes made Oc- 
tober 10th. 
SAND SERIES, PLANTED JULY 25, 1907. 
1 
Treatment 
Notes Sept, 6 
Weights ahd notes Oct, 10 
No. of 
plants 
Height 
inches 
No. of 
plants 
Height 
inches 
Weight of 
tops g 
Weight of 
roots g 
Root 
nodules 
507 
Check 
9 
.87 
7 
1. 
.2 
.14 
None 
508 
Check 
10 
.75 
7 
.75 
.2 
.12 
None 
500 
Check 
10 
1.00 
10 
1.25 
.5 
.17 
None 
510 
Manured __ 
10 
1.25 
3 
.75 
.1 
.10 
Few 
511 
Mfinnrpfl 
3 
1.12 
512 
Manured _ __ 
9' 
1.75 
5 
2. 
.7 
.20 
Few 
513 
ISTnt Sol 
8 
1.25 
514 
Nut. Sol 
10 
5.00 
10 
8.00 
15.2 
3.10 
Abundant 
515 
Nut. Sol 
10 
5.00 
10 
7.50 
15.3 
3.40 
Abundant 
