96 CIRCULAR 249, U. S. DEPARTMENT OF AGRICULTURE 
Most of the stems so used are the dried and ground residue of the 
nicotine-extraction and tobacco-saucing extract industries, including 
also the residue of leaf tobacco similarly used. Other offal such as 
dust, scrap, clippings, etc., represent only a minor item. 
Unstemmed tobacco contains from 3 to 7 percent of potash. The 
potash content of stems is higher than that of the leaf web. The 
usual range for previously untreated stems is considered to be from 
6 to 10 percent, although an analysis by Mehring (2/1) of 359 samples 
of stem material arriving at fertilizer plants, from nicotine factories, 
disclosed an absolute range in potash content of from 1.6 to 12.7 
percent, and an average of 6. Tobacco stems are therefore important 
as an organic source of this element in mixed fertilizers. Golden- 
weiser (1/1) reported the use for this purpose of 2,006 tons in 1917 and 
1,861 tons in 1918. The later development of American supplies of 
potash has eliminated tobacco waste from consideration in this 
respect. Tobacco also contains from 1.2 to 5.3 percent of nitrogen, 
and about 0.7 percent of phosphoric acid. It is not usually listed 
among the organic ammoniates, however, as the percentage of nitrogen 
is relatively small. Prices paid for stems by the fertilizer industry 
are based on the unit values of potash and organic nitrogen. 
It is estimated that from 40,000 to 50,000 short tons of stems are 
used annually as a conditioner in the manufacture of mixed fertilizers. 
Fairly large quantities of stems and stem meal unmixed, are sold for 
their potash, nitrogen, and organic or humus content, direct to 
consumers. The New England tobacco district and some truck- and 
citrus-producing areas are important consumers of tobacco waste in 
this form. 
The value of offal or waste tobacco in this industry arises not only 
from its content of potash, nitrogen, and other plant-food constituents, 
but from the stability of supply, the fact that the fertilizer elements 
are readily available, and its fine adaptability as a conditioner. 
jicotine.—Large quantities of tobacco waste, and leaf tobacco 
when available at low prices, are used in the manufacture of insecti- 
cides, mainly in the form of nicotine sulfate. Nicotine sulfate is in 
fairly steady demand for use in spray mixtures and for control of 
cattle, sheep, and poultry parasites. Nicotine bentonite, a develop- 
ment of recent years for use as a poison against chewing insects, is in 
commercial production. 
The nicotine content of tobacco is highly variable. Wide differ- 
ences occur between types, between leaves in different positions on 
the same stalk, and between the leaf web and the stem. In general, 
the nicotine content of tobacco varies from about 1 percent in the 
Maryland type to 4 or 5 percent or more in fire-cured. Rustica, 
produced in this country on a small scale and for insecticidal use only, 
contains from 5 to 10 percent. It should be noted in this connection 
that tobacco in manufactured forms has lost much of its nicotine 
content through volatilization which occurs in processing. 
The nicotine in tobacco is contained mostly in the leaf web. Stems 
contain much less, the average yield for stems of all types being not 
greater than 0.7 percent. The nicotine is recovered usually by steam 
distillation. | 
The major portion of the supply of nicotine is derived from factory 
byproducts such as stems and factory waste. An important quantity 
