RICE, one of the world's most basic commodities, is caught up in the complex web of trade politics.A staple to billions, this starchy grain is among many agricultural products whose prices and trade volume are subject to the whims of national governments. Farm products have largely defied attempts by the Geneva-based General Agreement on Tariffs and Trade (GATT) to impose regulations. The international institution is charged with the fair regulation of world commerce. GATT's Trade Negotiating Committee, scheduled to meet at the end of this month, will once again try to tackle the debate over agriculture, which has been called the linchpin of a successful current round of world trade talks. Government subsidies and closed markets are at the heart of the GATT dispute over agriculture. While attention has centered on US consternation over the internal supports of the 12-nation European Community (EC), the problems are global in scale. Producers and consumers alike pay a high price for the trade distortions which result from unfair trade practices.