Intensive systems would be key, he said giving established examples such as Norway’s MiljoGartnieret that during a seven-month growing season produced 2200 tonnes of organic tomatoes and peppers off just 7ha, and Australia’s conveyor-belt aquaponic herb and fish producer, Blue Farms.
“Their hallmarks are: precision crop feeding, recycling of all nutrients, water and energy, low or zero use of chemicals, biological pest control and pollination, hospital-style crop hygiene, specialty crops and elite quality control.
“Typically, these modern food-growing enterprises used one-tenth or less of the land and water required by traditional farming systems.”
Solar power would be used to extract freshwater from the sea in hot, food-insecure regions while giant floating greenhouses could provide fresh produce to coastal metropolises such as Shanghai, Tokyo or Mumbai.
Such systems would be climate-proof, unaffected by the shocks that will damage traditional outdoor farming.
“By 2050, with the right investment, urban horticulture and farming can supply half the world’s food.”
Such urban production would ease stresses on world soils, water, biodiversity and rural communities, allowing regeneration of grasslands and forests.
Modern food-growing enterprises are predicted to use less than one-tenth of the land and water needed by traditional farming systems.
A couple of delegates at Irrigation NZ’s conference said they weren’t convinced Julian Cribb’s predictions would come to pass.
“I don’t dispute global population growth and reducing arable area as drivers for change but I do think it is fanciful to talk about urban agriculture as a possible solution,” local farmer and irrigation scheme director Chris Dennison said.
“The capital cost of urban farming is so great that almost any rural investment initiative would have priority.”
Investing in more secure transport infrastructure would be a better way to safeguard mega-cities’ food supplies, he suggested.
Mid Canterbury farmer Rab McDowell questioned Cribb’s scenario of booming population in a world running out of food, fuel and minerals.
“World population is levelling off. Many countries’ birth rates are below replacement rates. For 200 years the real price of food has been declining, a measure of increasing plentifulness [and] with shale oil and gas, peak oil has now retreated by about a 100 years.
“Rather than being killed by their diets humans throughout the world are living longer and poverty is reducing.”
McDowell also noted Cribb used an extreme prediction of global warming – 5C-plus by 2100 – to support his forecasts.
“There will be challenges ahead and water will be one of them.
"But when someone like Cribb gets his starting points so wrong I have little faith that his predictions are well-founded.”
