How do we raise food production for a growing world population without taking up more land, water and resources? That’s a question that occupies a lot of agronomists and food scientists at the moment. It’s also occupying entrepreneurs, and there are fortunes to be made by those who can bring a profitable solution to market. One company with high hopes is Urban Produce, who grow indoors in vertical stacks. This means they can grow over ten times as much as a traditional farm could on a plot of the same size.
As far as Urban Produce is concerned, they are the solution – but I have a couple of further questions. The main one is that whenever I read about vertical farming, the farms seem to be producing hipster-food like wheatgrass or microherbs. If you’re lucky you might get basil or baby leaf spinach.
There’s a reason for this. These plants are nutritious, but more the point they are quick to grow and high value. We eat the whole plant, which means more of the artificial light and heat goes into something you can sell. They make economic sense in an urban context, where the value of the land means farmers have to bring in more cash per square foot to break even. Since a vertical farm isn’t cheap to build, high value crops will help to deliver an earlier return for shareholders. But man does not live by micro-herbs alone – even if one buys from Aerofarms, the world’s biggest vertical farming operation, which boasts that it is “able to grow over 250 different varieties of leafy greens and herbs.”
Clearly if vertical farming is to make a real contribution to feeding the world, it has to deliver calories, not just nutrients. Here we encounter a problem. It takes a lot less light and water to make leaves than it does to make fruit or grain. So plants that we eat as leaves – like spinach or lettuce – can be grown relatively easily. Vertically stacking a field of wheat or tomatoes would be a much bigger challenge, and the energy inputs for the light the plants would need just don’t make economic sense any more.
That doesn’t mean vertical farming has nothing to offer, but Urban Produce are jumping the gun when they declare themselves to be the solution. Useful, yes, but one tool among many. We’re still going to need good old-fashioned dirt-based growing for a long time to come yet.