SAO PAULO, Brazil, Nov 21 (Reuters) - Brazil's No. 3 soybean producerstate Rio Grande do Sul had planted 35 percent of its crop by Thursday,the state Agricultural Federation (Fecoagro/RS) said.Brazil's southernmost state is normally the last to plant and harvestin the world's second largest soy belt. Area planted to soy in the statethis season should grow 7.5 percent over last to 3.54 million hectares(8.75 million acres), said Fecoagro/RS in a statement."With El Nino, good yields are expected for soy and equally for corn,given the amount of precipitation expected during the growing season,"said federation crop engineer Valdir Bisotto.El Nino -- a global climatic anomaly associated with the warming ofsurface temperatures in the Pacific Ocean off the coast of Peru --typically causes heavy rains in Brazil's south from October throughDecember. The phenomena is believed to be responsible for the disruptionof world weather patterns, causing droughts and floods.Rio Grande do Sul accounts for about 17 percent of Brazil's soy output,which should reach a record 48 million to 50 million tonnes this season.Brazil's national planting had been estimated by analysts at around 50percent last Friday.Brazil is the world's No. 2 soy producer and exporter after the UnitedStates and accounts for about 24 percent of global soy supply.