SOIL EXHAUSTION AND ROTATION OF CROPS. Jg3 



The export of wheat from thos6 southern districts is immense. 

 Until our western country came into bearing-, that was the chief 

 source of the wheat supply to continental Europe. 



"\\ r e have in our Genesee region, in central New York, a country 

 where the soil is of remarkable natural fertility, and, after the 

 first few years of cultivation, the farmers fell into a routine which 

 enables them to take off a wheat crop ever} r third year, right 

 along, with great uniformity. The uniformity is great, so far as it 

 depends upon the feeding power of the soil. Accidents, like the 

 rust, the midge, or something of that sort may come in and des- 

 troy their crops occasionally, but the feeding power of those soils 

 remains, as a certain quantity, and will probably so continue for a 

 great length of time. 



The most interesting case which I can bring up in illustration 

 of the natural strength of soil is furnished by the English gentle- 

 man to whom I have referred, Mr. Lawes. In April, 1870, he 

 wrote, in respect to a field on his estate, a paragraph as follows : 



" The same heav} r loam, of no extraordinary fertility, has yielded 

 an average annual produce, without any manure at all, of 16 

 bushels of wheat for twenty-six years ; 20 bushels of barley for 

 eighteen years, and nearly 24 hundred weight (long hundred 

 weight) of hay for fourteen years." 



Mr. Lawes began, in 1844, to see what would be the effect of 

 putting a given plot of laud into the same crop year after year, 

 with no manure whatever ; and the result is what I have just 

 stated. These averages which he gives are, with one or two 

 exceptions, the regular yield, within two or three bushels, of this 

 piece of land. A field, for example, which had been, this last 

 summer, twenty-eight years in continuous cultivation under 

 wheat, has averaged about 16 bushels; on one occasion, it went 

 up to 23, and on one occasion it dropped down to five. These 

 variations were due to the season, but otherwise the yield ranged 

 between 12 to 17 bushels, so that this productive power of 16 

 bushels may be considered as the capacity of that soil in respect 

 to the wheat crop. I do not see any reason why he and his suc- 

 cessors should not go on for a hundred years and get the same 

 amount of wheat, within about the same limits. Perhaps it would 

 full off somewhat. There is a little falling off in the last half of 

 the period just completed. The yield is perhaps a bushel less 

 than during the first half; but that may be accidental, and due to 

 the character of the seasons. There is no reason in my mind why, 



