112 
IOWA ACADEMY OP SCIENCE 
PEAT SERIES. 
o 
eu 
Treatment 
Weight 
g 
No. Of 
plants 
Wt. per 
plant g 
Relative wts. 
Av. ch’Jss, 100 
76 
N. P. K 
33.3 
12 
2.77 i 
100 
77 
iSf. P. K. L 
30.8 
13 
2.36 1 
73 
Manure — - ' 
43.3 
13 
3.33 
146 
80 
Peat and N. P. K — _ __ _ _ 
3.5.45 
13 
2.75 
107 
81 
Peat and N. P. K. L — 
32.65 
12 
2.72 
105 
90 
2 peat and N. P. K. L 
35.55 
13 
2.73 
106 
It is seen that the three peat pots run remarkeably close together, and that 
even when double the portion of peat was added there was no advantage from 
its use. Although the peat here shows a slight gain over the pots having no 
peat, it is within the limits of error and not to be compared with the growth 
due to manure, which was 146. We can safely say that this experiment shows 
no benefit from the use of peat. 
The investigations have shown this: peat has a decided physical effect on 
the soil and while it is not identical with that of manure, still it is not far 
different. But peat does not benefit the growth of clover. Manure does. 
Therefore it is not the physical effect of the manure Vv^hich is responsible for 
the better growth of the clover, when the clover is grown in the greenhouse 
and the soil is put in good physical condition and well supplied with water. 
The question of the physical effect of the manure was attacked in a third 
way, namely, by using a liquid manure that carried fertility without at the 
same time giving the physical effect that the regular manure did. It is reason- 
able to assume that the physical effect of the manure lies in the coarse insol- 
uble part and that the soluble portion wmuld have little, if any, such effect. 
However, it was found that manure teachings applied to the surface of the 
soil retarded the loss of water in a very decided manner. King’^ found the 
same thing: He found that wetting the surface of a sand with the liquid which 
leached from farmyard manure decreased the rate at which water was lifted 
16 inches and evaporated from the surface 49.64 per cent. The explanation of 
this is that the soluble organic matter clogged the pores in the soil, stopping 
to some extent the capillary rise and evaporation of the water, in much the 
same way that salts deposited at or near the surface hinder the movement of 
water in the soil. This is not to be considered as indicating that the teachings 
have anywhere near the same physical effect as the bulky manure. They have 
some such effect, but it is small in degree. 
The main thing to be determined is,, what effect does liquid manure have on 
the growth of clover as compared to the regular manure? 
A series was planted March 7, 1906, to test this question and also the effect 
of smaller amounts of manure. “Manure extract” was used on pot 107. To 
obtain this the regular amount of manure was thoroughly mixed with water, 
and as it would not filter, the coarse material was strained and settled out by 
aid of the centrifuge. Considerable suspended matter remained, but probably 
not enough to have much humus effect. What was obtained was the soluble 
and very fine part of the sample of manure. A perfect elimination of coarse 
material was obtained in “manure leachings” which was the liquid which 
^Wisconsin Annual Report, 1893, p. 197. 
