In my area of the country corn and soybean harvest is progressing very rapidly. Yields are all over the board with corn running anywhere from 23 to 200 bushels per acre having essentially rainfall.
I know of four different fields of corn nearby that were alfalfa last year and corn did not even make 30 bushel. Yet corn on bean ground in the same area has had highs of 160 to 200 bushels per acre. Normally the alfalfa sod ground would have the better yields. This year however, sub soil moisture was greatly reduced because of the alfalfa roots.
An example of this is a local dairy firmer who for several years has been getting 170 bushels on his alfalfa sod. This year it yielded only 23 bushels, while his other ground yielded 100 to 120 bushels.