164 



SCIENCE 



[X. S. Vol. XXXII. No. 814 



area will hereafter increase less rapidly. 

 Much of the increase in wheat acreage will 

 occur in the older states, this being now 

 true for the year 1910. We have for the 

 first time reached the 50-million mark, the 

 acreage this year being 50,500,000 acres. 

 In 1950 at the rate of 6 per cent, on a farm 

 area of 1,330,000,000 acres, our wheat acre- 

 age should be about 80,000,000 acres. The 

 accompanying figure illustrates the condi- 

 tions that may exist by 1950, based upon 

 conservative estimates. 



An estimation of the possible wheat acre- 

 age by 1950 may be calculated in another 

 way. From the above table it will be 

 noted that the percentage of the total land 

 area in wheat has increased each decade on 

 an average over .3 per cent. — to be accu- 

 rate, .34 per cent. This percentage for the 

 period 1900-1909 is now known to be 2.5 

 per cent. If we add to this the same rate 

 of increase for each future decade from 

 1910 to 1950, the percentage will reach 3.86 

 per cent. It is likely to be a little greater, 

 as we are no doubt now entering a period 

 of considerable wheat expansion. It is 

 conservative, therefore, to assume a wheat 

 acreage of at least 4 per cent, of the total 

 land area in 1950, or 76,000,000 acres, an 

 amount almost equal to the other estimate. 



INCREASE IN PRODUCTION ON THE SAME 

 ACREAGE 



An erroneous opinion has widely pre- 

 vailed for some time to the effect that the 

 yield of wheat to the acre in the United 

 States is decreasing. On the contrary, 

 there has been a considerable increase, 

 amounting to 1.8 bushels in the past forty 

 years. Considering the past thirty years, 

 only, the increase has been fully 2 bushels 

 per acre, the yield during the second decade 

 having been less than that of the first. It 

 is really more accurate, however, to cal- 

 culate from this second decade of 1880- 

 1889 than from the first, as it was during 



the second period that the great extension 

 of the wheat area into the great plains and 

 western mountain states occurred, and 

 hence it was only by this time that average 

 yields would fully represent the entire 

 country. Two bushels increase on each of 

 46,678,400 acres, the present average wheat 

 acreage, equals over 93,000,000 bushels, 

 which is the present increase in production 

 over what it would be at the acre yield 

 prevailing thirty years ago. The present 

 average yield is 14.1 bushels. At the same 

 rate of increase above mentioned, this yield 

 should increase to 16.8 bushels in 1950. 



It must be remembered, however, that 

 each decade there is a much more rapid 

 diffusion of knowledge of improved meth- 

 ods of culture, seed selection, use of better 

 varieties, etc., and all farming wiU become 

 constantly more intensive. An actual in- 

 crease in acre yield, therefore, of six 

 bushels by 1950 ought to be a fair estimate, 

 thus raising it to 20 bushels. At this acre 

 yield the 80,000.000 acres of wheat in 1950 

 would produce 1.600,000,000 bushels. 



MEANS OF INCREASING ACRE YIELDS 



The increase of 2 bushels in yield per 

 acre attained during the past thirty years 

 has resulted without question through cer- 

 tain improvements in wheat culture, as the 

 soil and climate have probably become at 

 least no better. The means of accomplish- 

 ing these improvements are chiefiy three: 

 (1) the introduction of better adapted 

 varieties, (2) hybridization and selection 

 in existing varieties and (3) better meth- 

 ods of cultivation. 



Introduction of New Yarieties. — Up to 

 the present time by far the greatest im- 

 provement has been made through the in- 

 troduction of new wheats. As early as 

 1819 the U. S. Department of Agriculture 

 imported the Mediterranean, a semi-hard 

 winter wheat, which was afterwards so 



