How did US corn yield go from 60 bushels per acre in 1964 to 80 bushels per acre in 1969? Do you feel they added a gene that did not exist before?
I don't know but you have a couple of choices. They increased the acreage,they genetically modified the corn or it was through selective breeding.
Now how did it happen ?
Major uses of cropland, selected years, 1949-2002
Cropland used for crops Cropland Total
Year Harvested Failed Fallowed 1 Total 2 Idle 3 pasture 4 cropland 2
Million acres
1949 352 9 22 383 26 69 478
1954 339 13 28 380 19 66 465
1959 318 10 31 359 33 66 458
1964 292 6 37 335 52 57 444
1969 286 6 41 333 51 88 472
1974 322 8 31 361 21 83 465
1978 330 7 32 369 26 76 471
1982 347 5 31 383 21 65 469
1987 293 6 32 331 68 65 464
1992 306 8 24 338 56 67 460
1997 321 7 21 349 39 68 455
2002 307 17 16 340 40 62 442
1 Cultivated summer fallow.
2 Distribution may not add to totals due to rounding.
3 Includes all acreage diverted from crops under the Acreage Reduction Program (ARP), the
Conservation Reserve Program (CRP), and other Federal acreage reduction programs shown