Wheat futures are proving relatively easy to fathom, and indeed continued their slow upward progress on Wednesday.
While technically a rally, that implies an acceleration absent in the slow, but steady, progress of less than 4% in the three weeks since Chicago's December lot set a contract low of $6.36 ¾ a bushel.
But for row crops, movements are proving less easy to predict, with corn, for instance, opening the last session firm, but ending strongly lower without any apparent fundamental justification.
Markets are, in low volumes, displaying a "notable lack of conviction", Richard Feltes at Chicago-based broker RJ O'Brien said.
Some of that can be put down to a couple of events in the calendar.
There is prospect on Monday of the end of the month, often a period that sparks a little ennui as funds tidy up positions.
Furthermore, the US Department of Agriculture will then release its quarterly stocks data, a key report, for two reasons.
First, it gives an insight into domestic grains usage to which other data, such as exports and ethanol production, give a guide but miss out the important feed sector consumption.
Secondly, stocks reports have a history of causing huge price movements, when data turn out to be far from expectations.
(And these are 1.913bn bushels for wheat, 681m bushels for corn and 124m bushels for soydeans.)
'Traversing no-man's land'
Furthermore, there is something of a switch in market theme going on.
Traders are "traversing a 'no-man's land' where markets are transitioning from intensely supply-focused price discovery to drivers centred upon demand, investment flows and whether farmers will sell enough to meet demand in October, November and December," Mr Feltes said.
While harvest results are grabbing attention, so is evidence of demand, and to what extent prices down significantly over the past month for corn and soybeans are stimulating it.
Selling pressure to come?
In fact, Mr Feltes was hardly too cheery over price prospects, flagging that farmers have shown below-average advance sales of new crop corn and soybeans, suggesting "potential for above-average harvest hedge pressure in coming weeks, especially if row crop yields continue to exceed expectations".
And brokers queued up to point out the boost to harvest pace expected from dry Midwest weather.
"It was forecasted that favourable weather could be expected for the next few weeks which would boost the harvesting of the 2013 US corn crop," Joyce Liu at Phillip Futures said.
Furthermore, CHS Hedging reminded of the lack of competitiveness of US corn, saying that Ukrainian supplies "continue to be at a large discount to US corn for those in the world market".
Even the influence of the dry weather in parts of South America at the start of the sowing season for corn and soybeans is turning more neutral, with rains expected for most key areas.
"While there is currently some dryness across western Argentina and northern portions of Brazil, above-normal rainfall in those areas in October should improve conditions, allowing for better soil moisture as planting begins," weather service MDA said.
"Below-normal rainfall is expected across far southern Brazil, however, which may lead to some stress on corn and soybean germination."
Currently in Argentina, "farmers have only planted about 3% of their anticipated 2013/14 corn crop, which is about half the normal planting pace for late September" CHS Hedging noted.
Corn for December added 0.5% to $4.50 ¾ a bushel in Chicago, where soybeans for November gained 0.3% to $13.16 ¾ a bushel, as of 09:45 UK time (03:45 Chicago time).
Record Chinese prices
For wheat, however, the trickle of price positive news kept on coming, with prices in China hitting a record high, reaffirming the country's potential for turning to imports to quell values, which have been elevated by harvest rains which damaged the quality of the domestic harvest.
In Henan, the top growing province, the price of standard wheat hit 2,560 yuan ($420) a tonne, while the best-traded January contract hit a contract high of 2,885 yuan a tonne on the Zhengzhou exchange on Tuesday.
This amid consistent concerns about supplies of quality wheat, given setbacks from harvest rains, which tend to wash out milling quality, in Russia and lower protein levels in US and Canadian supplies.
Furthermore, it is not just dryness in Argentina that is causing concerns for the crop in the southern hemisphere's second-ranked exporting country.
"A freeze in Argentina's key wheat growing regions could ruin Argentina's 2013-14 wheat crop, causing overseas buyers to turn to U.S. wheat instead and supporting US wheat prices," Ms Liu said.
The opinion was not universal.
"The Argentine wheat crop saw temperatures as low as 26 degrees Fahrenheit on Tuesday night, but the majority of the crop is not developed enough to see more than minor damage," CHS Hedging said.
Still, it did not stop Chicago wheat for December gaining 0.5% to $6.61 ½ a bushel, keeping its premium to corn at just under $2.10 a bushel.
Progress was a little less impressive among soft commodities, with arabica coffee for December falling back 0.3% to 117.50 cents a pound in early deals in New York, despite some early strength in Brazil's real against the dollar.
A stronger real makes assets in which Brazil is a big player, such as arabica coffee, more expensive in dollar terms.
However, data from Anacafe showed exports from Central America, Colombia, the Dominican Republic and Peru up 7.7% last month at 241m bags, despite the outbreak of rust in Central America.
Raw sugar for October clung at the 17.42 cents a pound at which it closed the last session, the highest finish in four months, helped by data showing adrop in output in Brazil's Centre South.
'Bargain-hunting by food industries'
Elsewhere, in Kuala Lumpur, palm oil for December edged 0.1% higher to 2,304 ringgit a tonne, given some support by Intertek data showing Malaysian exports up 6.5%, month on month, for the first 25 days of September.
Phillip Futures, while a bear on palm oil prices, did flag "bargain-hunting by food industries and end-consumers whenever prices fall, as they are very under-covered.
"Their entry to the market at low prices [has] provided some support."