Media playback is unsupported on your device Media caption Singapore is looking to develop urban farming to create more sustainable food sources

In the middle of a concrete-covered housing estate in Singapore, Derrick Ng picks his way between the muddy rows of plants he is growing.

Barely bigger than a basketball field, it is an oasis of green in one of the most densely populated and urbanised cities in the world.

A former engineer, Mr Ng is one of an increasing number of people on the small island-state who are worried about the rising cost of food and have decided to try to do something about it.

And while it is a labour of love for the 31-year-old, it is also an important source of income, providing vegetables for his family's fish soup business.

"Before food prices went sky-high, my father was still able to make a living for himself," Mr Ng says, his legs and shoes caked with earth from his allotment.

"But everything was on the rise. He said it was not worth doing any more since the profit margin was pretty low. So I took over.

"Instead of giving up, I found other alternatives such as food resources that I can control."

Plants or houses?

High food prices are a major issue for Singapore, which imports more than 90% of its produce, and has to feed a population that is now in excess of five million.

But Singapore, which measures just over 700 sq km, was not always a net importer of food.

In the 1960s and 1970s there were about 20,000 farms on the island and it was self-sufficient in the production of poultry, egg and pork.

Image caption Singapore produces about 7% of its own food, including eggs, leafy vegetables and fish.

However, as development sped up, most of Singapore's arable land was used for infrastructure projects such as housing, offices and roads.

Today, there are only a handful of farms left, most of which are located in agrotechnology parks that take up less than 2% of Singapore's total available land.

In recent years, the government has tried to diversify and secure Singapore's food supplies, though much of its food still comes from nearby Malaysia and large producers such as China.

Singapore has been widening its use of contract farming and overseas food zones, where local buyers can control everything from production to processing.

Closer to home, in 2009 it set up a food fund worth 5m Singapore dollars (£2.6m; $4.1m) to support local farms and invest in research and development.

The government has also been trying to promote more creative methods of growing food, such as the urban farming projects similar to that run by Mr Ng, where residential or commercial areas can be used to grow fruit and vegetables.

Global appetite

While Singapore may seem like an extreme example, many experts are predicting that other countries could eventually face a similar set of problems; an inability to produce the food needed to feed their growing populations, and a heavy dependence on imported goods.

According to the United Nation's Food and Agriculture Organization, global food consumption has exceeded the amount grown in six of the past 11 years.

Each country is in a place where it needs to protect its own food security. There's no reason why they won't move into an every country for itself mode Janet Larsen, Earth Policy Institute

One of the main causes has been severe weather patterns that have damaged harvests and limited global production.

Earlier this year, the US was hit by its worst drought in more than half a century, while major growers in Russia and the Black Sea region were forced to cut their production forecasts following a heat wave.

As a result, overall global food prices rose by 1.4% in September, following a steep 6% rise in July.

''The supply for food is very unpredictable. Demand is more or less stable,'' says Lynette Tan, an analyst from Phillip Futures. ''Disruptions can happen at any time due to the weather.''

At the same time, analysts say that too many countries have failed to improve the efficiency of their food production and supply chains.

One study estimates that eight billion people could be fed with the amount of food wasted globally each year.

Food shocks

The problem for policymakers is that rising food prices often result in social unrest.

During the last food crisis in 2008, riots broke out across North Africa and the Middle East after staples such as bread became too expensive to purchase.

Image caption The poor people in Asian economies are likely to be hurt the most by a rise in global food prices

In India last year there were large street protests after the cost of red onions, used widely in cooked and raw dishes, quadrupled and sent the prices of other vegetables surging.

This sort of outbreak is prompting countries such as China, the world's second-biggest economy and home to many of the new consumers who are buying up global supplies of meat and grains, to step up their attempts to secure long-term food supplies.

China has been making record purchases of soybean, a key ingredient in the Chinese diet, to add to their reserve stock piles. It has also been looking to buy up vast tracts of farmland in countries such as Australia and New Zealand, often with limited success.

For the moment, China and other relatively wealthy countries such as Singapore are able to pay a premium for food that is imported or grown on their behalf in foreign fields.

The worry for organisations such as the Earth Policy Institute in Washington DC is that should nations fail to plan well enough for their food futures, then there will be an increased risk of clashes over crops and livestock.

"Each country is in a position where it needs to protect its own food security," says Janet Larsen, director of research at the Earth Policy institute. "There's no reason why they won't move into an every country for itself mode."

That is why home farmers such as Singapore's Mr Ng may prove to be so important.

From growing carrots along his corridor to running a community garden, he has been able to mobilise local resources to become increasingly self-sufficient.

Self-taught about agriculture, Mr Ng's urban garden has allowed him to save around 1,000 Singapore dollars (£510; $820) a year on his food business.

He eventually wants to make his small farm more commercial, and even start raising his own fish.

Mr Ng's hope is that should his neighbours follow his lead, then even a crowded modern metropolis such as Singapore could one day become a flourishing urban food factory.