12 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. 
Both phosphoric acid and potash are generally needed on practi- 
cally all the tobacco soils of the fiue-cured district, although potash 
is perhaps of somewhat less importance on the stronger soils of the 
Old Belt section. Neither of these materials is likely to do harm, 
and any unused portion will not be lost by leaching (except possibly 
on some of the very deep loose sands of the Coastal Plain section) 
but will remain to benefit succeeding crops of the rotation. It would 
undoubtedly be wise, therefore, to use these materials somewhat more 
freely than has been customary. In the New Belt this reeommenda- 
tion would apply more particularly to potash, because the soils there 
are relatively more deficient in that constituent, while in the Old 
Belt, particularly on the more clayey soils, phosphates are more 
urgently needed, although a considerable increase in the potash used, 
particularly on the lighter soils, would also be desirable. 
For general use it would seem reasonable to recommend as a base 
the use of from 400 to 600 pounds of 16 per cent acid phosphate per 
acre and in the Old Belt about 100 pounds of sulphate of potash 
(analyzing 48 to 50 per cent actual potash, K,O) or for the lighter 
soils of the New Belt 150 to 200 pounds of the sulphate of potash 
per acre. 
The amount of ammonia to be used with these quantities of phos- 
phoric acid and potash, as indicated above, would depend largely on 
the condition of the particular field under consideration. In gen- 
eral, it may be stated that proportionately more ammonia can be 
used profitably on the ight sandy soils of the New Belt than on the 
stronger Old Belt soils. Another factor of importance, particularly 
in the western part of the Old Belt section, is the time of harvesting 
and curing. If the crop ripens and is cured in warm weather, say, 
up to September 10, the tobacco will naturally tend to vellow well and 
cure bright, as compared with the same tobacco harvested and cured 
in the cool weather of late September and October. The normal 
period for curing tobacco in the New Belt is during July and early 
in August, which are hot-weather months, and this is a factor dis- 
tinctly favorable to a good bright cure. Tobacco that ripens and 
cures during hot weather, particularly if the soil be rather dry, can 
satisfactorily utilize a larger amount of ammonia than when the 
harvest is in cool weather, and wet weather just before the tobacco 
is harvested is an additional adverse factor. Increasing the phos- 
phorie acid, as noted above, will tend to brighten the leaf and thus 
overcome some of the harmful effects of too much ammonia. 
In the Old Belt section under average conditions, particularly 
on the stronger type of soils of the western part. probably about 
150 pounds of 16 per cent dried blood (or its equivalent in some other 
good ammoniate) would give approximately the right proportion of 
