Validity of rooftop farming

[mr friendly guy]

With the world population increasing and the developing nations urbanising and changing their mix of food intake to more meat, its only going to strain food production through increase demand for crops with decreasing land area to plant them. One of ideas I had tossed around in my head was whether its feasible to use the top of roofs from factories, flats etc to grow some vegetables, the same way people grow their own food in more developed nations. Heck I used to grow my own cucumber for cooking Hainan chicken rice. My parents also grow some of their own food.

Is anyone aware of studies being done to see how feasible this is? I know in China some people have tried it before.

Thoughts?

[General Zod]

We've got at least one going on in Brooklyn. http://rooftopfarms.org/

A lot of it is probably going to boil down to building codes and zoning laws though.

[Esquire]

The other thing to remember is that there's plenty of slack in the food supply, between inefficient land use, subsidized non-food crops (see: corn syrup), supermarket and other waste, and oversized portions. Actual, as opposed to percieved shortages shouldn't be an issue in the foreseeable future.

The above comes with the usual disclaimers, of course - not a professional, would be interested to see contradictory evidence if such exists, etc.

[StandingInFire]

Another solution would be to simply zone land better, so the most fertile/best growing areas stay farms and poor growing zones are used more for habitation (I can always dream people would be smart enough to do this) or improving food storage so less gets thrown out.

[madd0ct0r]

With the world population increasing and the developing nations urbanising and changing their mix of food intake to more meat, its only going to strain food production through increase demand for crops with decreasing land area to plant them. One of ideas I had tossed around in my head was whether its feasible to use the top of roofs from factories, flats etc to grow some vegetables, the same way people grow their own food in more developed nations. Heck I used to grow my own cucumber for cooking Hainan chicken rice. My parents also grow some of their own food.

Is anyone aware of studies being done to see how feasible this is? I know in China some people have tried it before.

Thoughts?

I should dig up some of the household hydroponics systems I saw in Vietnam. The "changing the food intake to include more meat" needs unpacking as an assumption.
India has the world's largest vegetarian population and, interestingly, has not increased calorie intake inline with economic growth.
China on the otherhand is a massive pork producer. Irrc the figures of pig production and observed consumption used to not add up, but it may have been reconciled now. Pork consumption has increased massively as a function of increased wealth but is allegedly slowing down now, possibly as a function of obese toddlers with heart disease.
my limited knowledge of Africa diet patterns hinges on the idea that as people get richer they eat less root crops (cassava) but the crop production just switches to feeding livestoc. (pigs again).

On the livestock side there's a key split between ruminants that convert grass and other low value agricultural side products (like treated rice straw) into human useful calories and animals like pigs and chiclens that require a higher grade food input. Household scraps don't scale to the large farming volumes we're discussing.
in short, guessing diet change is harder then weather prediction.

A final driver for household level rooftop stuff in developing countries is trust. It's known that stuff from the farm is likely to be soaked in chemicals, so people like to grow their own for a bit of reassurance. That's not a driver that will cross over to large rooftop farms.

Finally, you have competition from solar panels. There's not enough space for either to fill demand, and it's likely solar will win out.

[Broomstick]

A lot of it is probably going to boil down to building codes and zoning laws though.

Also building structures.

There are two ways to do rooftop gardens. One, you put a lot of dirt up there. This means the roof needs to support that weight, in addition to any other expected loads, like snow on top of the roof+soil in winter. You also have to have a way to provide water AND drainage that doesn't screw up the roof structure and cause leaks or other problems.

Two, use hydroponics. You'll still have weight issues, and even more so water supply/drainage issues, plus more materials for initial input and either human labor or some sort of automated controls.

Neither of these solutions are free and if the roof wasn't engineered for this from the start you'll need to do some remodeling.

I should dig up some of the household hydroponics systems I saw in Vietnam. The "changing the food intake to include more meat" needs unpacking as an assumption.

Depends on context. There are people in this world who are protein deficient, usually the poorest sorts. While they might not require meat, meat is a pretty handy source of protein, fats, and certain nutrients.

Perhaps part of what needs to be unpacked is the notion that meat = large animals like cows and pigs which are not the most efficient means to convert feedstock into meat.

my limited knowledge of Africa diet patterns hinges on the idea that as people get richer they eat less root crops (cassava) but the crop production just switches to feeding livestoc. (pigs again).

Africa is one of those areas where protein-starvation still occurs – cassava is almost entirely carbs, as are many other root crops. There's a reason the word for protein deficiency illness – kwashiokor – is of African origin. If they don't have livestock they'll tend to look to bush meat (wildlife) and you can hardly blame them given that lack of protein makes people sick. You either have to allow them some sort of animal protein or introduce high protein crops that can survive the climate and local pests.

On the livestock side there's a key split between ruminants that convert grass and other low value agricultural side products (like treated rice straw) into human useful calories and animals like pigs and chiclens that require a higher grade food input. Household scraps don't scale to the large farming volumes we're discussing.

Actually, chickens are pretty efficient at converting feed to human calories, and the hens have the added bonus that they can produce food without needing to be slaughtered (mmm.... fresh eggs!). It also helps they'll eat bugs and, as noted, kitchen scraps. Their small size makes them suited to small-scale operations and raising in the backyard, which would be a feature of “rooftop gardens” and better utilizing urban land. Not everything has to be commercial-scale farming and small-scale gardens are a definite industry. Regulations that used to ban livestock like chickens and rabbits from urban backyards are being relaxed and such small-scale livestock are starting to re-appear in cities.

Pigs have the problem that they largely eat the same food humans do, and aren't terribly efficient at doing so. They aren't small livestock and require more space than some smaller alternatives.

Finally, you have competition from solar panels. There's not enough space for either to fill demand, and it's likely solar will win out.

That is also a factor.

[Elheru Aran]

In Africa they do supplement their protein with various beans. Soybeans, black-eye peas, and so forth. They don't really keep chickens for eggs (although people do eat eggs over there, they're generally factory-farmed eggs rather than homegrown).

I still remember the time my brother visited some of his friends in the village, and they were very happy about the upcoming meal. He asked what the big deal was, and they replied, "There's a little bit of chicken in it!" Anecdotal, I know, but indicative of how people below a certain economic grade simply don't eat very much meat at all in Africa.