June 29^3 
Orange Trees in Sand and Soil Cultures 
8ii 
The precautions necessary in distinguishing between cause and effect, 
when interpreting analytical data of plant tissue, have already been 
emphasized (d). In the dry matter there is a progressive decrease in 
the percentage of total nitrogen in the sand and soil cultures as we pass 
from the leaves toward the root, where there may be a slight increase 
which becomes augmented in the rootlets, whose percentage is consider¬ 
ably below that found in the leaves but greater than that found in the 
shoots. 
The percentage of total sulphur was approximately the same for the 
corresponding parts of the trees in both sand and soil, the shoots and root 
in every case containing but a trace. 
The percentage of total phosphorus was usually somewhat greater 
for the sand than for the soil cultures. The leaves and shoots contained 
approximately the same percentage of total phosphorus; while the trunk 
and roots contained considerably less, with an appreciable increase in 
the rootlets above that of the roots. 
We find the total ash content of the parts examined to be greater in 
each case for the sand than for the soil culture. The ash of the leaves 
was approximately double that of the shoots which in turn was more 
than double that of the trunk and root. 
No significant difference as regards total ash existed between the trunk 
and root. It is of interest to note that the leaves and rootlets contain in 
their dry matter the greatest percentage of total ash .and of nitrogen, 
which no doubt indicates that here the assimilatory processes are most 
active. 
The percentage of CO3 constitutes approximately fomr-tenths of the 
total ash, except in the rootlets, where it is only about two-tenths. The 
large percentage of CO3 found in the ash of various parts of the citrus tree 
may indicate Siat not only the leaves, but the other portions of the tree 
as well, contain large quantities of organic acids. 
The percentage of SiOg in the ash varies widely in the various parts. 
The percentage content of potassium (K) in the ash of citrus leaves 
obtained in the field (Kelley and Cummins (6)) was approximately 20 
per cent when i week old, 13 per cent when 6 weeks old, 6 per cent when 
6 months to 2 years old, and 2 per cent when 3 or more years old. In the 
sand cultmes the potassium constituted approximately 25 per cent of the 
total ash of the leaves, about 17 per cent of that of the shoots and about 1 1 
per cent of that of the trunk and roots, respectively. In the soil culture, 
the potassium in the ash of all parts of the tree examined was approxi¬ 
mately 10 per cent. The leaves collected from trees in these cultures prob¬ 
ably ranged from 3 to 17 months of age and therefore represent a mixed 
sample so far as age is concerned. The data for potassium indicate that 
not only the age of the leaf but also the composition of the medium in 
which the tree grew may influence the percentage content of potassium 
in the various parts. The data do not necessarily conflict therefore with 
those obtained by Kelley and Cummins. 
The sodium (Na) content of the ash of the leaves and shoots is rela¬ 
tively small compared with that of potassium. The difficulty of accu¬ 
rately determining a small amount of Na in presence of considerable 
amounts of K will be appreciated by those familiar with anal)d:ical work. 
The data show that the trunk and root contain a much larger percentage 
of sodium in the ash than either the leaves or shoots. As the location of 
the sodium storage in citrus trees is of considerable interest and the data 
thus far obtained are too meager to justify any far-reaching assumptions, 
43323—23-6 
