Despite having lived and worked in some of the largest cities in the world for nearly 30 years, I am still in the habit of reading about the countryside. Some colleagues even call me old-fashioned.

Admittedly, the days have long passed when this nation employed food rationing. In some places people were used to going to bed hungry for weeks and not having a meat dish for months, not to mention the great famine of the early 1960s.

What keeps city people worrying now is diabetes and obesity. Neon lights and colourful posters line the streets promoting a whole range of services and facilities for people to look slim, or simply feel so.

However, this glittering array of urban business should not blind China, and its responsible citizens, to the fact that its rural economy is still weak, if not even weaker in relation to the ever-expanding power of the cities.

In fact, the more the cities grow, the greater the strain will be on agriculture, or the domestic supply of food. Cities are draining, to an increasing degree, rural resources  land, labour and finance.

As reflected in the 2006-10 development plan drafted by the central government, part of which is called "New Countryside," China really cannot afford to pretend it has grown into an industrial nation, and ignore its farming sector as of no general interest.

If China can manage to meet its targets, it will be producing 520 million tons of grain in 2010, and will keep its food imports below or around 3 million tons.

But the economy will be like a giant with muddy feet if farms are poor in productivity. And a drastic rise in demand for food imports, which the entire world would have difficulty coping with, would lead to tremendous uncertainty in the global system, endangering supply to other food-importing developing nations.

I say this not because I used to be farmhand in the 1970s and may still be emotionally attached to the country life. I cannot claim patent of the idea, although I can understand it perfectly. In fact the first time I heard it eloquently explained was in my interview with Dwight Perkins, a Harvard professor on Chinese agriculture, in the 1980s.

In the second half of the 1990s, rising meat consumption in turn caused a surge in the demand for animal feed, another use of grain. But throughout the 1980s and most of the 1990s, China managed its farms skilfully. It used primarily its small industries and small cities to keep rural society stable, and to boost farm output. The nation's grain output went up steadily. Even though every year it also imported some food, there was not a major change in the amount.

But from the late 1990s up to now, domestic grain output has seen more fluctuations. In 2003, its figure was even lower than 1990.

In the meantime, many things have changed. On the downside, many rural small industries have collapsed because of poor technology and vague property structure. Urban industries have become more competitive, at least in utilizing the markedly urban- and State sector-biased capital market.

Farmland has also been eroded, yielding to the seduction of the urban property development.  Huge numbers of rural youths have joined the urban industrial force  taking with them physical strength and knowledge.

The only positive thing I can think of at the moment is improved technology, especially better strains of crops, which allows for higher output per unit. In 2005, China's output peak was 4.6 tons per hectare, the highest in its history  though in terms of total output, the record is 1998.

Obviously, in order to make agriculture more productive, there need to be more positive measures. In its New Countryside programme, the government should extend truly useful social and financial backup to the workers who feed China, and help the world keep its food market stable.