8 Florida Agricultural Experiment Station

tube 1 inch in diameter was used. Approximately 20 plugs
6 inches deep were taken at random for each soil sample.

 Preparation of Samples
 Commercially grown vegetables are often coated with residues
from fertilizer dust and spray applications. This is a serious
source of contamination. Such residues should be removed in
preparation of samples for analysis. Usually it is considered
sufficient to wash samples in distilled water. Jacobson (13)
concluded that thorough washing of leaves with dilute HC1 is a
prerequisite for valid quantitative analysis for iron. This may
be advisable under certain conditions, but was thought to be
undesirable with the type of spray program followed on the
crops sampled in this investigation. It is recognized that wash-
ing of vegetative materials may remove small amounts of cer-
tain elements from the tissue itself.
 The cabbage heads as brought to the laboratory had 8 to 10
dark green outer leaves still attached. Six to 8 of these leaves
next to the firm head were prepared for separate analysis. They
were washed twice in tap water, using a fibre brush to remove
all foreign matter adhering between the large veins near the
base of the leaf, and were then rinsed twice in distilled water.
The firm cabbage heads were not washed. Approximately 1/8
of each head was taken by cutting out a representative wedge-
shaped plug. These plugs were loosened to aid in drying. A
plastic knife was used throughout the work for cutting up of
the samples.
 Collard samples were prepared by stripping the edible leaves
and petioles from the main stem. The leaves were washed in
the same manner as the outer leaves of the cabbage samples.
The coarse portion of the leaf petiole was separated from the
remainder of the leaf and the 2 portions were analyzed separately.
 Celery stalks were first topped near the center of the leaf
cluster and the upper portion was discarded. The roots were
cut off as close as possible without causing the stalks to fall apart.
The oldest outer stems also were discarded. Considerable scrub-
ing with a brush was necessary to remove residue from between
parallel veins at the base of each stalk.
 Beans were prepared by removing the calyx from the stem
end. They were washed and spread on cheesecloth until the
excess water had dried and then were cut into short pieces.