tons per acre.
4. Packed soil, covered with soil mulch, lost in 7 days 2.5 ozs.
water, equal to 34 tons per acre.]




CHAPTER VII

SOIL TEMPERATURE


We learned that roots need heat for their growth and development. Now
what is the relation of the different kinds of soil toward heat or
what are their relative powers to absorb and hold heat?

=Experiment.=--Some days before this experiment, spread on a dry floor
about a half bushel each of sand, clay and decayed leaf mould or black
woods soil. Stir them occasionally till they are thoroughly dry. When
they are dry place them separately in three boxes or large flower pots
and keep dry. In three similar boxes or pots place wet sand, wet clay,
and wet humus. Place a thermometer in each of the soils, placing the
bulb between one and two inches below the surface (Fig. 31). Then
place the soils out of doors where the sun can shine on them and leave
them several days. If a rain should come up protect the dry soils.
Observe and make a record of the temperatures of each soil several
times a day. Chart the average of several days observations. Fig. 32
shows the averages of several days observations on a certain set of
soils.