878 
Journal of Agricultural Research 
Vol. V, No. 19 
that certain algae, such as Spirogyra and Vaucheria, are resistant to the 
action of boron. Morel (n), however, states that very weak solutions 
of boric acid arrest the development of lower fungi and similar organisms. 
He suggests that boric acid may be used, like copper, to attack such 
diseases as mildew and anthracnose. The effect of boron on the lower 
plants, fungi, yeasts, etc., has been but little studied. 
Agulhon (i) and Bertrand (2) have stated that boron in small amounts 
acts as a stimulant to plant growth. Pellet (12) calls attention to some 
experiments which indicate that compounds of both manganese and 
boron, singly and combined, have no effect on the growth or yield of the 
sugar beet. He concludes that the results of other workers claiming a 
stimulation are too few and are untrustworthy. 
Many investigations regarding the effect of boron on plants and plant 
growth have been reported, but no attempt to review all such experi¬ 
ments is made in this paper. For a review of this subject the publication 
of Haselhoff (7) and the recent work of Brenchley (4), where various 
inorganic plant poisons and stimulants are discussed, should be consulted. 
EXPERIMENTAL WORK 
Very few of the previous studies have included a quantitative estima¬ 
tion of the boron present in plants, and no experiments concerning the 
effects of calcined colemanite (crude calcium borate) on plant growth 
have been reported. As both borax and calcined colemanite are valuable 
larviddes for the house-fly maggot, it seems advisable to determine the 
effect of manure treated with both borax and calcined colemanite on the 
growth of a variety of plants. 
The manure used in these tests was treated with the amounts of borax 
or calcined colemanite noted in the tables, and stood in the open for 10 
days before it was applied to the soil. For the plot tests, the manure 
was applied at the rate of 20 tons per acre and was then plowed under, the 
ground harrowed, and sometimes rolled and reharrowed, before planting. 
In nearly all of these experiments borax or calcined colemanite was 
applied to the manure in larger quantities than were required to act as a 
larvicide—i. e., 0.62 per pound per 8 bushels, or 10 cubic feet. When the 
manure was mixed with the soil at the rate of 20 tons per acre, 216 pounds 
of borax per acre were present. Furthermore, the manure was not 
allowed to stand and leach for longer than 10 days; consequently, practi¬ 
cally the entire amount of borax added reached the soil. 
When 0.62 pound of borax was applied to each 8 bushels of manure 
and the weight of 8 bushels of manure estimated at 115 pounds (the 
average weight of fresh manure containing a large amount of straw), 
100 pounds of manure contained 0.54 pound of borax, and when the 
manure was applied to the soil at the rate of 1 part to 40, the percentage 
of boron in the soil, calculating the weight of 1 acre of soil 6 inches deep 
as 1,750,000 pounds, was 0.0015. 
