60 On Gypsum. 
foot clover died, and a crop of crab grass shot up 
through it, and furnished a second cover to the land. 
1807 and 1808. In these two years all my corn ground 
as it was broken up or listed has been plaistered broad- 
cast, with from three pecks to a bushel to the acre, and 
directly ploughed in, and both the seed corn and seed 
wheat have been rolled bushel to bushel. In both, the 
crops have greatly exceeded what the fields have ever 
before produced. That cultivated last year has doubled 
any former product. But they have been aided in spots 
with manure, and the years were uncommonly fruitful. 
All the manure carried out in these two years has been 
sprinkled with plaister when spread before being plough- 
ed in, and several fields of the bird-foot clover have been 
plaistered. The results conform to those already men- 
tioned. 
1808, February. Plaistered four ridges of highland 
meadow oat at a bushel to the acre. No effect. 
Some of the inferences I make from these experiments 
are, that gypsum should be worked into the earth; that 
half a bushel or less to an acre, worked in, will im- 
prove land considerably ; that drought can defeat its ef- 
fects upon corn, but not upon the land, if it is covered ; 
that the weather is of no consequence at the moment it 
is sown, though the subsequent season is of great; that 
it may vastly improve red clover even as late as May ; 
that it increases the eflects of coarse manure; that a 
quantity less than half a bushel to an acre, is in some 
cases as effectual, as a much larger one; that excessive 
moisture or excessive drought destroys its effect ; that 
its effect is more likely to be destroyed, when sprinkled 
on the surface, than when mixed with the earth; that 
