888 
Journal of Agricultural Research 
Vol. V, No. 19 
stimulating action of boron on the nitrifying bacteria seems to follow in 
certain cases. 
The results at Orlando, where the same amounts of boron were added 
to the soil as at other points, but where the toxic action of the boron was 
marked and where soluble boron was found in the soils after several 
months, indicates that many factors are involved in the absorption of 
boron and its effect on plants, and that definite conclusions in studies 
of this nature should be drawn with great care. These results are sub¬ 
mitted as a preliminary study of this question. It is our purpose to test 
the cumulative action of boron in soils. 
SUMMARY 
(1) It apparently made little difference in the quantity of boron 
absorbed by the plants tested whether boron was added to the soil as 
borax or as calcined colemanite. The addition of lime with borax had 
no definite effect in preventing the absorption of boron. Wheat and 
oats absorbed very little boron, while leguminous and succulent plants 
absorbed comparatively large amounts. 
(2) Wheat, beets, cowpeas, and tomatoes grown in pots in the green¬ 
houses contained boron principally in the tops of the plants, and, with 
the exception of the beets, comparatively little or none in the roots. 
(3) The fruit of the tomato plants contained only traces of boron, 
while the fruit of the cowpea contained large quantities. Lettuce grown 
in the greenhouse absorbed boron in proportion to the amounts present 
in the soil. 
(4) Potatoes grown in the open showed, when mature, a small amount 
of boron in the tops and relatively large amounts in the roots and tubers. 
(5) The leguminous plants, string beans, soybeans, and cowpeas, 
which were very sensitive to boron, showed when grown in plot tests a 
more equal distribution of the boron among the roots, tops, and fruit than 
the other plants tested. 
(6) Radishes grown in plots contained much larger quantities of boron 
in the tops than in the roots. Analyses of entire plants of wheat, com, 
peas, and oats grown on plots in the South showed the absorption of 
boron in all cases, the peas absorbing the most. All of the control plants 
contained at least a trace of boron. 
(7) Samples of soil from some of the control plots showed the presence 
of acid-soluble boron, while several similar samples of soil from certain 
boron-treated plots showed no acid-soluble boron. Usually more soluble 
boron was found in the treated soil than in the control soil. 
(8) The yield of wheat from a plot heavily treated with borax was 
90 per cent of the manured-control yield and greater than the yield from 
the unmanured control. The wheat grains were sound and contained 
but a trace of boron. 
