218 [Senate 



that gypsum so eminently benefits the growth of red clover. And 

 hence reason would here suggest, that to determine the fitness of a 

 soil for clover, an analysis should be made ; if it contain gypsum, all 

 is right, and the clover will flourish ; but if not, then a dressing of 

 this material must be applied. This is the theory. Let us compare 

 it with practice. A hundred pounds of gypsum to the acre has often 

 doubled the clover crop 5 and a tenth part of that quantity, or ten 

 pounds to the acre, will produce in some cases very sensible effects. 

 After it is spread on the ground, and before any sensible effect is 

 produced on the crop, the rain has usually dissolved it and carried it 

 into the soil and among the roots of the young plants. It thus be- 

 comes intimately diffused through the soil. Now, will analysis 

 detect its presence 1 If the soil is a foot deep, half a grain to a 

 pound will indicate a hundred pounds to an acre. Yet this half a 

 grain to a pound is only one fourteen-thousandth part, though often 

 producing a most luxuriant growth of red clover. A tenth part of 

 that is only one hundredth and forty-thousandth part ; yet this mi- 

 nute portion often is found to exert a very visible influence in 

 growth ; though far beyond the-reach of ordinary analysis. A crop 

 of clover, of a ton and a half to the acre, contains only three times 

 this amount, or thirty pounds of gypsum, in its stems and leaves. 



Again ; twenty pounds of muriate of ammonia applied to an acre of 

 rye added five bushels to the product. * But this is only one-sev- 

 enty-thousandth part of the soil. One hundred and forty pounds of 

 guano added more than sixteen hundred pounds to an acre of hay. 

 But this manure, when diffuserl through the soil, constituted only 

 about a ten-thousandth part ; its proportion of phosphoric acid, form- 

 ing about one-eighth, and a very important ingredient, would be 

 about one eighty-thousandth part ; its sulphuric acid would consti- 

 tute less than a two-hundred-thousandth part, and its potash about 

 one three-hundred-thousandth part. I am not aware that many che- 

 mists claim sufficient skill to determine such small proportions in the 

 soil ; yet these experiments show their great practical influence when 

 existing as added constituents. 



The ammonia of the atmosphere is considered by eminent chemists 

 as holding a very important relation to the healthy and vigorous 



• Johnston's Lectures, Appendix, p. 29. 



