1 
VoL. LXXVI. NKW YORK, AI’UIL 14. 1017. Tr No. 44l'5. 
_ - ■■ === 
Land Plaster and Lime 
Why Gypsum Was Formerly Used 
When I was a boy my graudfathei used land pla.stor 
on his corn and olbvor. No land pla.ster has been used 
in this section' for '40 years— everyone is using lime, I 
among the rest. I used lime on corn and tomatoes for 
"liiue" is a conibiiiation of the metal calcium and 
oxygen. Limestone is a cai'bonate of lime—tliat is 
c.ilcium and carltonie acid. The burning drives 
away the carbonic acid and leaves the lime. Land 
plaster or g.v]»sum is a sulphate of lime containing 
snl]diur with the lime. Thus the two differ not only 
phur which it contains the jdaster has a more acid 
effect upon tin' soil, and the lime i!i it would not 
give an alkaline elfi'ct until it had bc'come separ¬ 
ated from the suli)hur. As most farnuM's know, the 
u.se of lime u])ou potato(‘s will usually increase the 
scab, while plaster may be dusted over the seed 
two years, ;ind with no b('i'iefit. so f:ir as I could .see. 
I>ut I can I'emember how land plaster benefited corn 
and clover. Since tlu' farnu'rs ceased to use plaster on 
their corn I have si'en no such dark green luxuriant 
growth as I saw when a boy. ^^’hy do not farmers 
use it now, and why is it not advertised? I., n. K. 
Silver Creek, N. Y. 
EPEATING AN OLD STORY.—We have had a 
number o2 letters like the above, and it i.s clear 
that the old story of lime and land plaster (gyp¬ 
sum) should be told once more. What we call 
Turning the Old Sod Into a Seed Bed. Fig. 202 
in theii’ comiiosition. but also in their chemical 
action. For instance, when lime is put with ma¬ 
nure or other organic matter containing nitrogen 
the tendency is for it to make a combination which 
di'ives off ammonia in the form of a gas. When 
plaster is put with, the manure the chemical 
change is to form the .sulphate of ammonia, which 
is a solid. The lime is much better for sweetening 
the soil, as its action is direct. Owing to the sul- 
without any danger. Some years ago it w'as a com¬ 
mon practice to scatter plaster in the drill when 
pl:inting potatoes, and to dust plaster over the 
plants as they came up. This was said to prevent 
Idight and rot, the credit being given to the sulphur 
in the plaster. In the days before liquid sprays be¬ 
came common, plaster was u.sed mixed with Paris 
green for killing i)otato beetles. 
PLASTER AND CLOVER.—Up to 50 years ago 
