98 WISCONSIN AGEICULTUEE. 



would appear to be conclusive of its value. Thus one experi- 

 menter reports a field capable of yielding but 2 qrs. and 4 

 busli's, increased in the crop by an application of plaster to 4 

 qrs. and 6 bush's per acre. 



Michigan farmers are in the habit of using it with a view to an 

 increase of the wheat crop, and report favorably, although some 

 are of the opinion that it retards the growth and renders it 

 thereby more liable to rust. They are beginning, however, to 

 apply common salt, in small quantity at the same time, and will 

 doubtless, hereafter avoid the rusting, since salt is a quickener 

 of germination, and promoter of the ripening of the grains 

 generally. 



The soils to which it is most appropriate, or, at least, in aid of 

 which its effects are most marked, are light, dry and sandy. — 

 Two reasons are obvious: First, a soil of this sort more readily 

 allows the permeation of water and the more easy absorption of 

 the elements in solution ; and, secondly, sach soils are usually 

 more deficient of both the lime and sulphuric acid. Of course, 

 stiff and clayey soils, being less porous, will retain the gypsum 

 for a longer time, and afford it less access to the ammonia of the 

 atmosphere. But whether the soil be clayey or sandy, one thing 

 appears to be essential, viz : either kuTnus must be abundant, or 

 decaying animal manure present in some quantity, as otherwise 

 the plaster appears to be comparatively powerless ; which cir- 

 cumstance would seem to favor the opinion, entertained by 

 many, that its chief value consists in its power to fix ammonia ; 

 for, during the decomposition of organic substances, ammonia 

 is a never failing product, and if not at once appropriated by 

 sulphuric acid, or some other powerful agent capable of render- 

 ing it non-volatile, its escape would be inevitable. And yet, on 

 the other hand, if the soil be remarkably rich in organic matters, 

 there is danger that the organic acids, resulting from this decom- 

 position, such as humic and geic^ combine with the lime of the 

 gypsum in so great quantities as to release too much sulphuric 

 acid for the health of the plant. 



As to mode of application^ scientific men are pretty well agreed, 

 although some difference exists as to the form, — a few maintain- 



