MISCELLANEOUS SOILS. 
57 
land. This is partly because the cold air which forms on the 
surface of all the ground at night tends to flow down and col¬ 
lect in low places, but it is also the result of the fact that the 
loose, spongy soil of peat marshes does not conduct the heat re¬ 
ceived from the sun during the day downward. In consequence 
of this, the lower layers of soil do not become warmed in peat 
marshes as they do in other earthy soils and the little heat left 
in the surface inch or two of soil is rapidly lost at night by 
radiation, so that the freezing point is frequently reached on 
such soil when it would not be on more earthy soils such as 
sandy loam or clay loam which would conduct the heat down¬ 
ward better during the day and so keep warm farther into 
the night. 
This difficulty with peat marshes can be overcome to a cer¬ 
tain extent by heavy rolling which, by compacting the soil, per¬ 
mits the heat to be conducted downward more readily. It will 
also to a certain extent become less in time, as the peat decom¬ 
poses and takes on more of the character of muck. Neverthe¬ 
less, it must always be expected that marsh land will be more 
subject to late spring frosts and early fall frosts than high land. 
It may be stated as a general guide, that the occurrence of 
killing frosts is as liable on marsh land at any given point as 
it is on upland soil having good air drainage about 150 miles 
farther north; in other words, the marshes of Dane county 
are as liable to have a frost which will kill corn as early as are 
the upland regions of Shawano, Marathon, or Clark counties. 
The marsh land regions of Jackson county are liable to have 
frost tw r o weeks or more earlier than the hill tops of the same 
latitude. This means that corn and potatoes, while safe crops 
for the upland region, are not safe crops for the marsh land 
and should not be depended on as the chief crops. 
CHEMICAL COMPOSITION AND FERTILITY OF PEAT 
The chief difference between peat soils and upland soils con¬ 
sisting largely of earthy matter, is that they have relatively 
small amounts of the mineral elements phosphorus, potassium, 
calcium, and magnesium, and have extremely high amounts of 
nitrogen in the organic matter. The average per cent of phos¬ 
phorus in the peats in this region so far analyzed is 0.135 per 
cent. This means that in an acre of soil to a depth of a foot 
