YALE AGRICULTURAL LECTURES. 43 



even the most miraculously sensitive balances or tests of the 

 infinitesimal sample, whether the 2,000,000 pounds contain 

 enough phosphoric acid, or ammonia, or other ingredients 

 to raise a crop ? Take a barren soil, for instance, or one 

 called so, on which the application of 400 pounds of guano will 

 make all the difference of sterility or a crop. Now, can a 

 chemist tell in his laboratory, by testing 100 grains of that soil, 

 taken promiscuously from all parts of the field, whether the 

 guano had or had not been added ? Verily not, says Professor 

 Johnson. And so our young agricultural chemist takes, issue 

 on the question, and is prepared to do battle with our beauti 

 ful pet theory d Voutrance. He thinks that if one would take 

 50 pounds of soil, and wash it with an enormous quantity of 

 water, to dissolve out the soluble salts a little job which 

 would take at least a fortnight, and might a month he might, 

 by analysis, find whether there was a great excess or deficiency 

 of plant food in the field from which the sample came. But 

 the cost and trouble of the experiment are serious objections 

 to putting the scheme into practice. 



The most fertile soils contain the finest particles; or, in other 

 words, soils are like linen, better for having fine texture. 

 Most soils are deficient mechanically rather than chemically. 

 There is great store of plant food, but not finely enough divid 

 ed. A field, therefore, which, in a certain state of pulveriza 

 tion, will produce 15 bushels of wheat, would, or should, yield 

 30 if worked up twice as fine. Why ? Because there is twice 

 the amount of surface of particles exposed to the action of 

 heat, and cold, and rain, and therefore twice as much plant 

 food set free. Take your multiplication table and figure up 

 this idea as far as you like, and then you will see the use of 

 sub-soil plows, and clod-crushers, and good harrows, and deep 

 plowing, and all these modern contrivances for breaking up 

 our fields into a good seed-bed. 



