Commodities started Friday with cautious steps.

Asian share markets rose, continuing to react to Thursday's US jobs data, showing a bigger-than-expected drop in new unemployment claims and a bigger-than-expected rise in private sector positions.

But commodity investors looked ahead to the next set of US employment statistics, non-farm payrolls data, due later, which are closely-watched and notoriously difficult to predict.

London copper eased, setting course for a fourth successive weekly decline, and Brent crude was a touch lower as of 09:00 UK time (04:00 Chicago time).

The dollar hardly helped by strengthening 0.2%, making dollar-denominated exports, such as many commodities, less affordable to buyers in other currencies.

'Bigger picture negative'

Agricultural commodity markets got off, generally, to a soft start, an exception being cotton, which edged 0.2% higher to 70.38 cents a pound for December delivery, proving again its ability to defy negative news.

This time, this came from the International Cotton Advisory Committee, which edged its estimate for world cotton inventories at the close of 2012-13 680,000 tonnes higher to a record 16.39m tonnes, citing better hopes for production and worse ones for consumption.

"The bigger picture remains negative," Luke Mathews at Commonwealth Bank of Australia.

Cotton prices fell overnight in China too, with Zhengzhou futures for January shedding 0.3% to 19,505 yuan a tonne.

However, there was some thought that, technically, New York cotton had been oversold in dropping to a one-month low earlier in the week.

Wasde approaching

But in Chicago, it was corn's late decline in the last session which set the tone for this one, with prices hardly helped by FCStone estimates for US crops, ahead of the US Department of Agriculture's latest Wasde report next week.

The broker estimated the US corn harvest at 10.881bn bushels, on a yield of 124 bushels per acre, compared with current USDA figures of 10.706bn bushels and 122.0 bushels per acre respectively

For soybeans, FCStone pegged output at 2.959bn bushels on a yield of 39.1 bushels per acre, compared with USDA estimates of 2.86bn bushels and 37.8 bushels per acre.

Further estimates are expected later on Friday from Informa Economics, which has also tended to be on the more optimistic side of the market for this year's crops.

Demand setbacks

Furthermore, there was still some surprise at the strength of Brazilian corn export data on Thursday, showing a record for a third-successive month, this time of 3.66m tonnes.

The shipments took the total so far in 2012 above 13m tonnes, already an annual record high with two months of shipments yet to come.

Nor were ideas on the US export front helped by Israel booking only 50,000 tonnes of corn from a 90,000-tonne tender, and that expected to come from Ukraine, another blow to ideas of demand turning yet to the US as supplies elsewhere wane.

And the support corn prices have got from the domestic market spurred on Thursday by strong ethanol production data - took a dent too with a drop of up to 17 cents a bushel in the basis at Mississippi and Illinois river terminals thanks to a shortage of barges, which has reduced merchants' need, or appetite, for paying up for now.

'Ukraine sold out'

More will be known later on the export market when the USDA unveils weekly export sales statistics expected to show corn shipments at 100,000-350,000 tonnes, compared with 142,400 the previous week.

For soybeans, sales are expected at 550,000-700,000 tonnes, beating the 522,200 tonnes last time, and for wheat at 350,000-500,000, allowing a reduction from the 571,900 tonnes the previous week despite ideas of US supplies growing in competitiveness.

Richard Feltes at RJ O'Brien said: "Cash sources advise us that Russia is not offering wheat for January and that Ukraine is effectively sold out," boosting hopes for European Union and US sales.

Soymeal conundrum

Brian Henry at Benson Quinn Commodities flagged dynamics in markets for soymeal, of which sales of 125,000-225,000 tonnes are expected, in line with the previous week's 176,700 tonnes.

"The EU continues to show interest. There is plenty of interest in South East Asia, while destinations in North Africa and Mexico are also shopping soymeal."

However, China's shipments, at 875,000 tonnes, are running at some twice year-ago levels, questioning the country's need itself for the huge quantities of soybeans it is importing.

 "US soybean prices have gained plenty of support from soymeal exports, which makes continued soymeal offers by the Chinese longer term bearish the US soy complex," Mr Henry said.

'Better chances for moisture'

Furthermore on the negative side, there are ideas of an easing up in the weather extremes – to wet in northern Brazil, too wet in the south and Argentina – which have hit sowings, leaving Argentine farmers alone some 2.3m hectares behind on corn and soybean plantings.

Weather forecasts "indicate better chances for moisture in dry regions of northern Brazil and perhaps a drier trend in southern Brazil and northern Argentina", Mr Henry said.

And the USDA attaché in Buenos Aires eased some of the gloom over corn in saying that the rain, while hampering Argentine sowings short-term, at least boded well for soil moisture levels to get them through summer heat.

Corn for December eased 0.1% to $7.50 ½ a bushel, while November soybeans lost 0.7% to $15.48 a bushel.

January soybeans lost 0.7% to $15,48 ¾ a bushel.

Wheat estimate cut

The attaché was more downbeat over wheat, cutting the production estimate to 10.8m tonnes, below a USDA forecast of 11.5m tonnes, if remaining above estimates from the Buenos Aires grains exchange at 10.1m tonnes, and the Rosario grains exchange at 10.0m tonnes.

And Societe Generale, forecasting further wheat prices "upside",  put in a caution that the poor start for US winter wheat, at its worst condition at this (early) time in the growing season since at least the 1980s, probably would have some bearing on final yield expectations.

That helped Chicago wheat at least to remain steady at $8.68 ½ a bushel for December delivery.