I farmed at Zhejiang Shaoxin countriside in late 1970s, mostly rice and wheat. Most output around 1500jin per mu or 750kg per mu, or 4500kg per US Acre (1 US Acre = 6.07 Chinese mu).
However in Illinois most farmlands can only cultivate for 1 season, and only for corn, wheat or soybeans. The average output of corn about 2500kg per acre, or $1000USD per acre at present price. The area shown in the picture total of 323 acres can produce $323,000 USD annually.
In Illinois, most farmland costs about $2000 per acre. Recently the price surged for more than double due to high demand for corn/soybeans. Neverthless most farmland still cost <$5000 per acre. I bet the total price for 323 Acres in this aution will be about $1million or so. The gross profit margin for a farmer is now = 323,000/1million = 32%.
One needs to hire seasonal labors (mostly come from Mexico) for 3 months; renting farming machines & equippment, supplying water (plentyful in Illinois) and electricity. Assuming total cost of $100,000, one can still yield $223,000 for a $1million investment, more than 20% of output.
From Nov to next May, the farmer coud enjoy all his/her holidays elsewhere in Chicago, or somewhere Hawaii.
Keep in mind, land is a big piece of realestate. The area is the mid of St Louis and Chicago. It is only about 30 miles away from the headquater of S&P giant Caterpillar company. The farmland may be re-zoning to a commercial land, or windfarm land in the future. The estate price will definetly surge for sure.
