No. 144.] 553 



of water. To supply the exigencies of the plants, therefore, it is 

 only necessary for the meadow to imbibe three and a half grains 

 of carbonic acid gas with every pound of water. 



The supply of nitrogen must be independent of the soil. 



With respect to ammonia, one thirtieth of a grain in every 

 pound of water is sufficient for the exigencies of vegetation, and 

 there is probably no spring of water in the earth that contains so 

 little. 



As to sulphur and phosphorus, the quantity needed by vege- 

 tation is 540,000th of a grain of sulphuretted hydrogen per cubic 

 foot, diffused through the atmosphere to a height of three thou- 

 sand feet, Mr. Baudrimont, of Bordeaux, says there exists in the 

 soil interstitial current?;, which exert an influence on agriculture; 

 there is a natural process at work, by which liquid currents rise 

 to the surface from a certain depth in the ground, and thus bring 

 up materials that help to maintain its fertility, or to modify its 

 character. He explains many phenomena of agriculture and ve- 

 getation hitherto inexplicable by his theory, and admits of no 

 relation between the fertility of a soil and the quantity of ferti- 

 lising matter expended upon it. He says the goodness of a soil 

 depends upon its inorganic constituents Seed from a barren soil 

 is likely to be more true to its kind than well manured land. 

 Land can be plowed too much, because of the too trequent loosen- 

 ing of the soil the decomposition of humus is so rapid as to over- 

 balance the benefit supposed to arise from exposure to the atmos- 

 phere. The Rev. S. Smith, of Germany, took a field of four 

 acres, that had been tilled one hundr- d years, and plowed it tho- 

 roughly ; he then sowed grains of wheat three inches apart in the 

 rows, and the rows a foot apart, and left three feet between each 

 three rows, which he trenched with the spade in the fall, and 

 scarified in the spring. When harvested, the yield was forty 

 bushels per acre. The adjoining field had four plowlngs, ten tons 

 of manure, seven times more seed, and yielded a quarter less to 

 the acre. He repeated this experiment for years with the same 

 result. 



