It is easy to imagine a stack of soybeans.
But how about a negative pile? A bean black hole?
It is possible one might become evident in the next few months, even on Monday, when the US Department of Agriculture releases its monthly Wasde crop report, a key event of the agricultural commodity traders' diary.
While March Wasdes are usually among the lower profile editions, this one could be among the few to reveal negative soybeans, as USDA analysts battle with the challenge of matching large consumption of US soybeans with, apparently, not-so-substantial supplies.
Demand for soybeans continues pretty much unabated.
Forecasts for 2013-14 soybeans in Wasde report, (existing figure)
US ending stocks: 141m bushels, (150m bushels)
Range of estimates: 130m-150m bushels
World ending stocks: 71.46m tonnes, (73.01m tonnes)
Range of estimates: 69.50m-72.90m tonnes
"Don't overlook processing margins for soybeans and corn ethanol which remain well above average levels," Richard Feltes, at RJ O'Brien, said, even if there is some suspicion that the impact of porcine epidemic diahorrea virus (PEDv) on the hog herd might begin to tell on feed demand.
And on exports, well, half way through the 2013-14 season and the US is already overdrawn.
It has sold, or already shipped, 44.17m tonnes of the oilseed, 7.5% more than the USDA forecasts for the whole of 2013-14.
That might not matter so much if there were plenty of soybeans to be found.
The USDA faces a similar picture in corn, where the US has committed to 93% of exports forecast for 2013-14, a record proportion for the time of year.
But as Don Roose, president of Iowa-based broker US Commodities, said "there are still adequate supplies of corn around," which can soak up an increase to the forecast for US exports which many expect in Monday's Wasde.
For soybeans, the picture is not so simple, given that even under current estimates, the US already looks like it will be running on vapours at the end of the season, in August.
The 150m bushels the USDA has pencilled in for domestic soybean inventories for the end of 2013-14 may sound a lot.
Forecasts for 2013-14 corn in Wasde report, (existing figure)
US ending stocks: 1.488bn bushels, (1.481bn bushels)
Range of estimates: 1.431bn-1.656bn bushels
World ending stocks: 156.27m tonnes, (157.30m tonnes)
Range of estimates: 154.80m-158.40m tonnes
"Last year, the USDA did not lower its stocks forecast from February to August from 125m bushels," then considered the pipeline minimum, "and many believe we are in the same situation this year," Rich Nelson chief strategist at Chicago-based broker Allendale said.
So if the stocks figure is not reduced, how will the USDA balance the books?
One way is to stick by its existing forecasts, and there could be cause to believe that the US will sell fewer soybeans than it has committed to, if Chinese buyers ditch purchases and switch to South American supplies as they often do at this time of year.
"The balance sheet is fiercely tight in soybeans, until we see China starting to cancel orders," Mr Roose said.
And that could be around the corner.
"China is now bloated with soybeans. Soymeal basis levels in China are in retreat and ships are backed up to unload soybeans," he said.
At Allendale, Rich Nelson said the USDA "may not be so aggressive" in raising its forecast for soybean exports.
Besides, there is always the potential for considering that some 2013-14 exports can be met from early production from the 2014-15 harvest.
But if USDA officials want to raise their soybean export forecast and keep the stocks, the same they could do so through the, rare, use of a kind of oilseed antimatter, a negative figure for the "residual" column, a rather amorphous element which represents something of a relief valve on the balance sheet.
Forecasts for 2013-14 wheat in Wasde report, (existing figure)
US ending stocks: 570m bushels, (558m bushels)
Range of estimates: 549m-615m bushels
World ending stocks: 183.65m tonnes, (183.73m tonnes)
Range of estimates: 182.10m-185.0m tonnes
"Supply estimates and reported use through May, coupled with the USDA's June 1 stocks estimate, indicate a below-average residual," the department said at the time.
At AgResource, chief economist Bill Tierney, told Agrimoney.com that "what the USDA is saying is that we think the production estimate will be changed down the line to give us more soybeans".
The USDA often changes soybean production estimates in September Wasde reports, the year after harvest.
"Last year, they raised the estimate by 19m bushels, the year before, for 2012, they raised it by 38m bushels," said Mr Tierney, a former principal grains economist at the USDA.
And the rises can be quite large, with the 2007 crop upgraded by 91m bushels in September 2008, equivalent to 3.5% of production.
"This year, 3.5% would be equivalent to 115m bushels. That could be enough to take ending stocks well over 200m bushels."
Not that a negative residual is the only factor on investors' minds heading towards Monday. Array
Range of estimates: 20.8m-24.0m tonnes
Range of estimates: 52.7m-54.0m tonnes
Range of estimates: 65.45m-70.5m tonnes
Range of estimates: 86.5m-90.0m tonnes
"I don't think the market is thinking that there will not be a record South American harvest this year, it just won't be quite as big as had been hoped," Mr Tierney said.
Mr Nelson said: "You might see 1m-2m tonnes taken off the Brazilian soybean crop, but that probably would not affect the market too much."
And then there is the Crimea crisis to consider, and whether the USDA will recognise a boost to US crop exports from concerns over Ukraine's reliability as a shipper, with Russian troops deployed in its south.
"Ukraine's deliveries have not been a problem yet," Mr Roose said, adding that the USDA is "not usually so premature" in making adjustments to balance sheets so soon into an event is difficult to predict.
However, Mr Nelson said that with US export sales strong even last week, before Russian troops entered Crimea, "it looks like even during the early part of the Ukraine, the US was getting more sales from foreign buyers worried about buying from Ukraine".
"We may find that, because of the Ukraine situation, the USDA is a bit more aggressive" when it comes to lifting its forecast for US corn exports.
Not that any such upgrade would leave the US at risk of reporting negative corn.
That is not just because of the ready supplies left over from last year's record harvest, but is a matter of methodology too.
For soybeans, with exports and crush numbers closely monitored, "the balance sheet is known. It forces USDA analysts to do it," in resorting to a negative residual figure, Mr Tierney said.
For corn, "there is the huge feed and residual use element which is not measured", meaning any discrepancies get swallowed up there.
Of course, this leads to its own difficulties, in interpreting, for instance, the level of inventories the USDA reports for main crops every quarter.
But, with a stocks report due in three weeks, that is another story.