Soybeans 47
interferes least with other farm operations. For seed produc-
_ tion the standard varieties should be planted not later than
June 15 in southern Kentucky and June   in the northern
part of the state. Not only is there danger that later plantings
may be killed by frost before the seeds mature, but the yields
are likely to be considerably less. Soybeans planted as late `
as July 1 or even later in the southern part of the state will
mature sufficiently to make hay, but give lighter yields than -
earlier planting.
CULTIVATION.
_ Wlien the field is smooth and free from trash, soybeans can ·
be cultivated with a weeder or spike—tooth harrow as soon as
leaves have formed. Such cultivation is very effective in de-
stroying weeds that may have started in the rows and also i
keeps the weeds ’down and thc soil loose between the rows until
‘ the plants are large enough for row cultivation. The weeder
or harrow should not be started too early in the morning be- I _
cause the plants are quite brittle at that time. At the Ex—
periment Station a riding cultivator with three or four shovels _
on each gang and provided with fenders is used for subsequent
cnltivations. Wlieii the beans are planted in 28 or 32-inch '
, rows, the wheels of the cultivator must be set close together.
Wliere the space between the rows is so narrow, one passage of
the cultivator cultivates two rows quite effectively. Of course
the rows straddled are cultivated closer and better than the
outside rows so the latter should be straddlcd at the next cul- l
tivation. One large grower of soybeans in Kentucky uses a
it sugar beet cultivator which cnltivatcs four rows at one time,
and hc claims satisfactory results. The rows must be very
· evenly spaced, however, to use such an implement effectively.
After the plants are large enough to shade the space between the
rows further cultivation is unnecessary and cultivation after
the beans begin to bloom is probably injurious. Usually three
cnltivations are sufficient. Ridging the rows makes difficult
_ harvesting and preparation of the ground for small grains. It
can be avoided by using narrow shovels on the cultivator.
Extremely deep cultivation is unnecessary.