Jan. 6,192.1 
Sand Drown , a Chlorosis of Tobacco 
29 
muriate of potash in place of the sulphate, other conditions being the 
same, there was a marked decrease in the amount of disease and an 
appreciable increase in the size attained by the plants. In a second set 
of plot tests, in which a more detailed comparison between the muriate 
and sulphate of potash was made, the striking effect of the sulphate in 
inducing or aggravating the disease was fully confirmed. In the first 
set of plots the standard rate of application of the potash salts was 80 
pounds per acre actual potash (K 2 0 ), while certain plots received 40 and 
160 pounds per acre. In the second series of plots the rates of application 
were 12, 24, 36, and 80 pounds per acre. In the first series the normal 
application of phosphoric acid was 64 pounds per acre in the form of 
16 per cent acid phosphate, and the normal application of nitrogen was 
32 pounds, various forms being used. Even the smallest applications 
of potassium sulphate produced marked effects in increasing sand drown. 
It is obvious that these quantities are much too small to produce injury 
by unduly increasing the concentration of the soil solution, and, moreover, 
corresponding quantities of potassium chlorid have shown no injurious 
action of any sort. The peculiar action of the sulphate, contrasting so 
sharply with the chlorid, seemed perplexing, for, while in recent years 
considerable stress has been placed on the necessity of an adequate supply 
of sulphur for the plant, no case has been previously recorded, so far 
as known, in which small quantities of sulphates caused serious injury 
under field conditions. 
A series of single-row tests was carried out at the Oxford station in 
which sodium chlorid, sodium carbonate, and calcium carbonate were 
used, in addition to the normal application of potassium sulphate, dried 
blood, and phosphorous in the form of so-called precipitated bone, a 
finely divided dicalcic phosphate. The common salt and sodium car¬ 
bonate were used at the rate of 200 pounds and the calcium carbonate 
at the rate of 1,000 pounds per acre. The sodium carbonate was not 
effective in preventing sand drown, and the calcium carbonate was only 
partially effective, neither of these materials causing appreciable increase 
in growth of the tobacco. On the other hand, the sodium chlorid 
(ordinary commercial “salt,” sold in bulk) probably increased the growth 
of the tobacco by fully 100 per cent, and there was no sand drown. The 
next season another series of row tests was carried out in which chemi¬ 
cally equivalent quantities of the chlorids and sulphates of sodium, 
calcium, and magnesium were used, in addition to a standard application 
of 100 pounds per acre each of ammonium nitrate and monopotassium 
phosphate. All salts were approximately chemically pure, and the 
quantities used were on the basis of 100 pounds sulphate (S 0 4 ) per acre 
or the equivalent quantity of chlorin. In this case the sodium chlorid 
and the calcium chlorid were without effect in controlling the sand drown. 
Both the sulphate and the chlorid of magnesium, however, showed a 
marked effect in preventing the disease; and this observation first gave 
the clue to the situation, as will be shown in subsequent paragraphs. 
RELATION OF ORGANIC MATTER TO SAND DROWN 
On the fertilizer test plots at Oxford several different sources of nitro¬ 
gen were used—namely, nitrate of soda, ammonium sulphate, dried 
blood, and cottonseed meal. These materials were applied at rates to 
furnish about 32 pounds nitrogen per acre, the quantity of cottonseed 
