Soybean contracts on the NCDEX fell ahead of the onset of monsoon and firmness in the rupee against the dollar. The most active June contract was down 1.4%. Earlier-than-expected arrival of monsoon in Kerala has raised hope sowing of the oilseed will be higher in the country. According to India Meteorological Department, monsoon may advance to parts of Kerala in the next 24 hours. The likelihood of acreage under the oilseed rising is seen bearish for prices. Higher arrivals of the oilseed are also seen weighing on prices.