Chicago soybean futures rose more than 1% on Monday, gaining for a seventh consecutive session as dry weather in key suppliers Brazil and Argentina stoked supply concerns.
Corn rose to its highest since July 2019, while wheat gained for a second straight session.
"Chinese buying has been really strong and we have dry weather issues in South America," said Phin Ziebell, an agribusiness economist at National Australia Bank.
The most-active soybean contract on the Chicago Board Of Trade (CBOT) rose 1.1% to $11.94-1/4 a bushel as of 0449 GMT, not far from the session high of $12.00 a bushel, the highest since June 2016.
Corn gained 1.5% at $4.34-1/2 a bushel, after climbing to its highest since July last year at $4.35 a bushel. Wheat rose 1% to $6.05-1/2 a bushel.
Chicago soybean futures forward curve shows prices have jumped for all contracts through to the middle of next year.
Argentine soy planting advanced sharply over the past week after rains in key drought-hit areas, the Buenos Aires Grains Exchange said on Thursday, though much of the country remained dry.
Strong demand for U.S. soybeans, led by the world's top importer China, is supporting prices.
Ukraine has harvested 60.3 million tonnes of grain from 14.6 million hectares, or 95% of the sown area, as of 19 November, economy ministry data showed on Friday.
Large speculators cut their net long position in CBOT corn futures in the week to 17 November, regulatory data released on Friday showed.
The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, switched to a net short position in CBOT wheat and cut their net long position in soybeans.