* Soybeans erased early gains after the dollar turned higher -- a bearish signal for dollar-backed US grains and oilseeds -- and US crude oil futures pared early advances. * March soybean futures matched their Jan. 3 high of $12.44-3/4 in overnight Globex trade but failed to break through resistance and move higher. * Additional pressure from much-needed rains that fell in the last day in Argentina, bolstering soybean yield prospects. Up to 3.5 inches fell in parts of Buenos Aires, said Drew Lerner of US-based World Weather Inc. * Soyoil gained against soymeal as meal/oil spreads corrected. Also, some traders expect an improvement in demand for soy-based biodiesel. * USDA in its February crop and supply/demand reports is expected to show a small reduction in US soy ending stocks and lower its estimates of South American corn and soybean production. * Crop forecaster Agroconsult lowered its forecast of Brazil's 2011/12 soybean crop to 71 million tonnes, down 3 percent from its previous forecast.