144 FARM GRASSES OF THE UNITED STATES 
or early fall, Theseed may be drilled, or sown broad- 
cast and covered by harrowing. 
The distribution of Johnson grass is shown in Fig. 
28, each dot on the map representing a correspondent 
who reported it as an important grass in his locality. 
The map shows it to be confined to those portions of 
the country where the ground seldom or never freezes 
to the depth reached by the plow. It will be noticed 
that a well-defined area of Johnson grass extends across 
the State of Alabama a little south of the centre, turn- 
ing northward into northeastern Mississippi. Maps 
showing the distribution of cotton and also of the negro 
population show this same area ina similar manner. 
It is due to the peculiar soil of that region. This isa 
broad, fertile strip of black prairie soil, rich in lime 
and other plant-food. An examination of the geolog- 
ical map shows this strip to coincide with the rocks of 
the cretaceous period. With proper drainage, alfalfa 
does well on this soil. The same soil occurs again in 
an enormous area in northern and central Texas, form- 
ing the famous region of black waxy soil of that State. 
Johnson grass is perfectly at home throughout this 
portion of Texas, but it does not, by any means, con- 
fine itself to these cretaceous soils in the South. 
‘Few grasses will stand greater extremes of moisture 
than Johnson grass. It luxuriates in moist soils and 
along the banks of drainage and irrigating ditches, but 
is at the same time noted for its ability to resist drouth. 
It makes very little growth in exceedingly dry weather, 
but lies dormant, and springs up vigorously as soon as 
rain comes again. 
