228 BOARD OF AGRICULTURE. 



We shall have occasion to speak of its use in connection with 

 other manures, when we speak of the compost heap. We now 

 allude to its use by itself, as a top-dressing. 



On some soils it is not so satisfactory as on others. But our 

 pastures are many of them covered with the white honeysuckle. 

 These are often called clover lands. On all clover lands, 

 whether reserved for pasture or mowing, plaster generally has 

 a wonderful influence. A bushel, or two bushels to the acre, 

 have been known to double the crop, and to add more than 

 twenty times its own weight to it. Even greater results have 

 followed. For if we may believe one of the most distinguished 

 chemists,* every pound of nitrogen which we add to the grass, 

 increases the produce one hundred and ten pounds, and this 

 increased produce of one hundred and ten pounds is effected by 

 the aid of a little more than four pounds of gypsum, or plaster. 

 Another accurate investigator — Sir Humphrey Davy — found by 

 actual experiment that the ashes of an acre of red clover, con- 

 tain no less than three bushels of plaster of Paris. This impor- 

 tant fact proves that the earth already contains a large amount 

 of this substance, and that it is essential to the growth of 

 clover. This may, perhaps, explain the so-called clover sick- 

 ness in some land. The requisite supply of plaster has been 

 exhausted. In any case, the addition of plaster to clover lands, 

 and especially to pastures, is of the highest importance. 



The effect of charcoal is somewhat similar to plaster. Char- 

 coal will absorb ninety times its own bulk of ammonia, Vv'hich 

 is held from escaping till it is separated by water and carried 

 into the earth for the plant. When dry, the operation of fixing 

 the gas is repeated till the next shower sends the gas into the 

 earth, and the particles of water take its place in the charcoal. 

 In this way, as a top-dressing, charcoal as well as plaster, per- 

 forms the most important functions. If we take any decaying 

 animal matter, which has begun to give off its offensive and 

 noxious odor, its ammonia, and cover it with charcoal or plas- 

 ter of Paris this escaping gas is immediately stopped. No infec- 

 tious odor arises from it. The decay of the substance has 

 suddenly ceased. This simple fact will show the intelligent 

 farmer to what purposes these substances may be applied. His 

 choice of these should depend somewhat on the expense of pro- 



* Boussingault, Ann. de Ch. et de Phys. t. 43, p. 243. 



