The First Book of Farming

Tempe

. Now what is the relation of the different kinds of soil toward

s 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

e soils increased until the early part of the

TEMPERATURE

in pot of

ILS AR

Your hand is warmed by heat radiated from the sun or warm stove through the air

lly be carried its entire length until it becomes too hot to hold. This carrying of the heat from particle to particle through the length of the rod is called heating by conduction. Now when the warm rays of the sun reach the so

ause the particles of the clay lie so close together that the heat pass

m air and warm rains can enter read

ther. You doubtless know that manure from the horse stable is o

by the decaying or rotting of the manure. More or less heat is produced by the decay of all kinds of organic matter. So

ILS LO

n the others and will gradually become dry. This is because some of the heat of your finger i

l loses heat by the evaporat

rod. The heat is radiated from the rod through the air to your body and the rod gradually cools. In the same way the soil may lose i

CH INFLUENCE S

s tell us that it takes a great deal more heat to warm water than it does to warm other su

f the dry soils the hu

ine on the cloth covered bulbs. The mercury in both thermometers will be seen to rise, but in the thermometer with the dark cloth about the bulb it will rise faster and higher than in the othe

clay warmer th

y than the sand, and, as the particles were smaller and more

mus and clay cooler

n the sand, they must have absorbed more heat, but they also h

G.

t of dry and wet soils during a period of

G.

ains clay subsoil; 2, clay subsoil and fert

at the sam

act texture. Of the wet soils the sand was the warmest, because, on account of its holding less moisture, less heat was required to raise its temperature and there was less cooling by evaporation, while the o

k losses of hea

heat by evaporation will be checked also. The mulch will also check the conduction of heat fro

F ORGAN

he organic matter not only furnished food for the corn but during its decay prepared mineral plant food that was locked up in the clay, and also brought about better conditions of air and moisture by improving the texture of the soil. The plants in the second box had sufficient plant food, but did not make better growth because poor texture prevented proper conditions of air and moisture. "And that's another witness" for organic matter. Decaying organic matter or humus is really the life of the soil and it is greatly needed in most of the farm soils of the eastern part of the country. It closes the