The US Department of Agriculture believes that foreign countries may own up to 40,000,000 acres of farm land.

No one really knows despite the Agricultural Foreign Investment Disclosure Act of 1978 requiring it. 

No one is worried that China will claim their farmland is organic and just use conventional pesticides, like they do now with an alarming amount of imported "organic" food, that makes no difference except in how much gullible people are willing to spend, but the Biden administration should want to know if land is being purchased near military installations, like they did  near Grand Forks Air Force Base in North Dakota. Or any other strategic target by countries like Russia, Iran, and North Korea.

Government is an inefficient, leaky bucket - their data has a month number 13 and negative values for some acreage, because government - but that isn't the sole reason little is known. The Biden administration has refused to give USDA the money, even though Congress mandated for the process to finally be online by 2025.

Not only is it unclear how accurate the information is, counties are having to submit this stuff by hand.

We're in proxy wars with four different countries now, it isn't an issue having a foreign subsidiary owning farmland, they can grow corn as well as anyone, but where those purchases are happening should be accurately known.