Grain markets were awaiting direction from weekly US government crop ratings published after the market close on Monday for a further indication of growing conditions.
Soy markets were also consolidating after Friday's rally in soyoil triggered by a court ruling that challenged the US Environmental Protection Agency's attempt to cut the amount of biofuels, made mainly from corn and soybean oil, required to be mixed into US fuel.
The most active soybean futures on the Chicago Board of Trade gave up 1.2 percent to $10.01-1/4 a bushel by 1150 GMT while corn dropped 1.3 percent to $3.83 a bushel.
Market participants have been grappling with weather forecasts and field reports to establish the extent of crop stress due to dry conditions.
"Weather conditions are still at the centre of concerns with small rains on the Corn Belt during the weekend, pushing traders to some selling," consultancy Agritel said in a note.
The light weekend rain, heavier rain forecast later this week in some areas and moderate summer heat may help corn and soybean crops, although the drier western Midwest remained a concern.
"GFS and EC both agree on cool temperatures over the US, but EC still shows little moisture relief for beleaguered corn and soybeans in the west," Thomson Reuters Agriculture Research analysts said, referring to the widely used GFS and EC weather models.
Dry weather has been more severe in the northern US Plains, hitting yield prospects for spring wheat, but large harvests in Europe and rain relief in Australia were serving to underline ample global supplies.
The most-active CBOT wheat contract was down 0.9 percent at $4.76-1/2 a bushel. Earlier in the session, it fell to $4.73 a bushel, matching last Wednesday's low, which was the weakest level since late June.
"Global wheat and corn supplies are ample, so it is hard to further push prices higher because of the US drought," an Australia-based agricultural commodities analyst said.
"As of now, the primary concern is over supplies of high-protein wheat."
Hot and dry weather during the growing season slashed yield prospects for US hard red spring wheat to the lowest in nearly a decade, scouts on an annual crop tour said last week.
But in Europe, French farmers have made swift progress in harvesting wheat and Russian production estimates are being revised up, although heavy rain in Germany is causing concern about quality damage.