Right now, my rough profit on corn or beans is ...

[erikjohnson61y]

Here's my Beans math:

APH 53 bu/ac (South Dakota). $12.50 expected new crop price. $663/ac revenue at APH

Seed $75 incl treatment
Chemicals (Pre's, Liberty, EnlistOne, Volunteer) $75 incl application (3 passes)
MAP 90# $910 = $41, Potash 110# $44 = $68, S 10# $.64/lb = $6.40.   Total = $115
Fuel 5gal/ac x $2.75/gal = $14
Taxes $21/ac
Repairs and Supplies $35/ac

Total Costs $335

Gross profit before depreciation, interest expense, living expenses = $328/ac.

Substitute rent for property taxes on my rented ground and it's $199/ac.

That's (much) less profitable than corn for me, given the assumptions.  Not sure how you can get to 6x costs for corn unless you're pulling seed out of the bin, not fertilizing, or using a row cultivator!!

[BA Deere]

Theoretically if one was tight and wanted to mine his ground, don`t put any fertilizer on ever, put beans on beans on beans and get 30 bushel per acre year after year with only the expense of machinery, herbicide and seed.  You wouldn`t get far doing that with corn though.