The reply by the Agri-Food and Veterinary Authority (Certificate required to prove food is organic; May 8) to the letter (Who checks on claims of foods being organic?; April 29) raises even more concerns and questions on the authenticity of food labelled and sold as organic in Singapore.

I have seen organic corn that is supposed to be grown locally, but there was no mention on the label as to who certified that farm to be organic.

A conventional farm needs to undergo three years of stringent and expensive checks by certifying bodies in order to be qualified as organic.

There are organic vegetables in our supermarkets that are imported from as far as Holland and Peru, aside from Australia, Malaysia and Thailand.

So my questions are:

•Is it not possible for a certified organic farm to produce a small amount of organic food for show and authentication purposes, but then supply many tonnes more from an adjacent non-organic farm and lump them all together as organic?

•Is it not possible for the suppliers to Singapore supermarkets to import a small amount of certified organic produce, and then mix this with non-organic produce and label all as organic? Who checks on this aspect and how is it done?

As an agronomist, I can safely say that it is technically and agronomically near-impossible to produce truly organic food consistently, season after season and year after year, and in large amounts.

This is especially true in the tropics where pressures from diseases and pests are extremely high, as there are no cold winters to break their life cycles. The limited arsenal of organic pesticides is not robust and efficacious enough.

The AVA says original organic certificates are needed for verification and even then, "when required".

This can certainly lead to fraudulent behaviour along the organic food supply chain.

The AVA needs to have a more drilled-down and robust system to ensure the organic food that consumers are paying for is indeed organic.

Liew Ching Seng