[maxerickson]

The US plants more soy than wheat already so the adapting part would probably go OK. The bigger question would be the math about calories (it probably works out, meat production consumes a lot of calories).

I guess we could also plant lots of potatoes (which produce more calories/acre than soy).

[hga]

And the more meat a county eats, the more is can divert stored feed for that purpose, modulo grain sorghum, which isn't normally a human food, to directly feed humans.

[Detect]

Feed Conversion Ratio (FCR) for cattle is about 10, pig 3, sheep 5, and chicken 2. That means we could feed about 10 times more people per hectacre on grains than using that grain as feed for beef. Ruminants are important for nutrient cycling and other ecosystem services, but far from efficient as a food source for humans. They are best utilized on marginal land where agriculture isn't ideal.

https://en.wikipedia.org/wiki/Feed_conversion_ratio

[hga]

Yeah, in the US at least, the normal pattern is to raise cows on pastures, sometimes out in the dry west fantastic acreage of it, 1,000 acre ranches can be considered tiny, 10s of thousands are not uncommon, and/or including grazing rights.

Then they're sent to a feed lot for some period of time to fatten up.

Ah, from the article you linked: "However, comparisons of FCR among different species may be of little significance unless the feeds involved are of similar quality and suitability."

So cattle might be more efficient than appears at first glance, since as ruminants they're initially fed stuff you can't feed other animals (ADDED: including humans), especially "on marginal land where agriculture isn't ideal", or perhaps as part of a crop rotation cycle. Alfalfa is a 3-for, a rotation cycle that's not e.g. corn or soybeans, a nitrogen fixer, and tasty food for cows.

And all the above isn't the best for our topic at hand, for that alfalfa and such isn't stuff we can digest, nor is silage from corn leftovers, so it mostly feedlot cow food we could redirect to humans.

[Detect]

I agree with you that it's mostly feedlot grains that we could redirect to humans, and that feedlot grains is a surprising amount of what we produce in total.

"More than half the U.S. grain and nearly 40 percent of world grain is being fed to livestock rather than being consumed directly by humans"

http://news.cornell.edu/stories/1997/08/us-could-feed-800-mi...

[hga]

And in the US, corn burned for ethanol, which is 40% or so of it. Now plenty of that food value is passed on to animals, the largest byproduct is "distillers dried grains with solubles (DDGS)", which is 31% by weight of the original corn, so it's not entirely wasted on that boondoggle today, but all of it could be redirected. Europe also has biofuels programs, doesn't it?

The title of your link: "U.S. could feed 800 million people with grain that livestock eat, Cornell ecologist advises animal scientists"

What, and give them type 2 diabetes?!?!!

Seriously, a lot of the usual suspects should reconsider their animus towards animal husbandry in the light of the increasing evidence the move to a low fat, high carbohydrate diet caused and is causing untold morbidity and mortality.

[TrevorJ]

Topsoil erosion would be a massive problem.

[schiffern]

Topsoil erosion is already a massive problem.[1] So far we've been able to mask the damage by substituting fossil fuel inputs for soil fertility, but realistically soil husbandry is the only sustainable way to grow food.

Heck, many people nowadays aren't even aware that soil organisms can manufacture bio-available nutrients from local minerals and the air.[2] The dominant view of soil seems to be as an inert tank that needs to be "refilled" with imported fertility.

[1] http://www.fao.org/docrep/t0389e/t0389e02.htm

[2] http://www.youtube.com/watch?v=x2H60ritjag

[hga]

That's something you start worrying about after you make sure no one is likely to starve, it can most likely wait a couple of years.

[TrevorJ]

Actually, it's something you worry about now if you don't want people to starve.

[hga]

This discussion is in the context of a sudden failure of a variety of crops, e.g. https://en.wikipedia.org/wiki/The_Death_of_Grass

In that context, for a couple or so of years you don't worry about soil erosion, except to avoid a repeat of the Dust Bowl, you worry about people not starving. Before AKA "now", and after the emergency period, yes, you worry about it, as we do now.