-j6 gypsu:.i. 



the soil ; once the surface is thoroughly ioaked, much that falls 

 drains off, passes away by the ditches, and is lost with all it may 

 contain that would prove beneficial to vegetation. It is in fact alto- 

 gether impossible to make any approximation, even of the roughest 

 kind, in regard to the quantity of rain-water that soaks into and that 

 runs off the ground ; and thus no kind of estimate can be formed of 

 the relation between the moisture absorbed by plants, and that which 

 escapes direct by the evaporation, without passing through them at all. 



But even in admitting that it was really the ammonia contained 

 in the rain-water, to which the very considerable increase of the 

 crop of clover, lucern, and sainfoin was owing, it would still be left 

 for us to explain wherefore, meteorological and other circumstances 

 remaining the .same, the same relative effects were not produced 

 upon natural meadows covered with grasses, upon hoed crops, such 

 as beet and turnips, and upon wheat ; finally, the most serious ob- 

 jection that can be urged against this theory is founded upon the 

 fact, that gypsum has no truly beneficial effect upon artificial mea- 

 dows, save and except when the soil to which it is applied contains 

 an adequate proportion of azotized organic manure. In a moderate- 

 ly manured soil, gypsum, as all the world knows, produces no sen- 

 sible improvement ; and as M. Crud, one of those men whom long 

 experience has placed at the head of practical farming, said : It is 

 to throw away both money and trouble to put gypsum upon an un- 

 kindly and impoverished bottom. It would seem, however, that if 

 gypsum really fixes ammonia in the soil, in consequence of its action 

 upon the rain-water tbat falls, converting its carbonate into sulphate 

 of ammonia, the ammoniacal salt once introduced into the soil, ought 

 to act independently and witliout the concurrence of another manure. 

 That it really does act isolatedly, and of its own proper force when 

 it exists, has been proved by the experiments of M. Schattenmann, 

 who demonstrated on the large scale the beneficial effects of the 

 sulphate of ammonia directly applied to natural meadows. It is 

 obvious, that if tlie tbeory which I discuss be true, the greater num- 

 ber of practical observations which I have quoted must necessarily 

 he false ; or, on the contrary, these observations being accurate, the 

 theory nuist be erroneous. 



I have given reasons for maintaining tho accuracy of the practical 

 results ; nevertheless, the better to establish this conviction, I have 

 thought it advisable to aild a few ficls to the many that are already 

 extant. I was, therefore, induced to undertake a series of experi- 

 ments with a view to study, indepeiulently of all hypothetical idea, 

 tlie action of gypsum upon certain hoed crops and cereals. 



These experiments were made upon patches of land of 140 square 

 yards each. Every precaution was taken to render the experiments 

 strictly comparable one Tith another. Thus tlie ground appropri- 

 ated to each particular crop was divided into three e(iual contiguous 

 zones. The first zone. A, always received gypsum in the ratio of 

 4| bushels per acre. The second zone, B, and the third zone, C, 

 were not gypsed. Each zone was sowed with the same quantity of 

 ieed, or planted with nn equal number of beet plants or potatora 



