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Heavy chaff trails reduce sugarbeet yields

Heavy chaff trails reduced strip-till sugarbeet yields by about 3 tons per acre in a southern Idaho study.

The same project also found that shanking nitrogen into soil instead of using broadcast applications helped prevent stand and yield losses.

“It appears that residue cover, nitrogen application method and N application rate can all impact sugarbeet production,” says Amber Moore, University of Idaho Extension soils specialist.

Moore and colleagues with UI Extension and the USDA conducted the research from 2009 to 2011 near Kimberly.

Beet yields dropped from 30.3 tons per acre in experimental plots having 6.9 tons of residue left behind by combines to 27.8 tons in plots with 10.8 tons of residue.

In plots having 14.8 tons of small-grain chaff trails per acre, for example, the beet yield fell to 27.1 tons.

“We believe that one of the reasons for this is because beets are staying wetter under heavier residue,” Moore says. “Roots don’t do well when soil remains saturated.”

When moisture levels remain high, nitrogen losses could be greater.

“Farmers should consider cleaning up heavier chaff trails, especially in areas having 9 tons or greater per acre to avoid reduced yields,” Moore suggests.

To find out how much residue is present, collect the chaff from several 1-by-1-foot sections that are a good representation of the field. Then multiple the weight of each sample in ounces by 1.36.

Seven ounces of relatively dry chaff collected from a 1-square-foot section, for example, indicates that particular acre contains 9.52 tons of chaff, an amount that will likely reduce yield (7 x 1.36 = 9.52).

Moore recommends either distributing strip-till residue evenly over the entire field using a chaff spreader, or in fields with heavy residue, removing some of it for use as livestock bedding or compost material.

She hopes future studies shed light on the cost-effectiveness of removing excess chaff. “My guess is that it would be financially advantageous, and that’s something we hope to find out.”

Moore points out that some chaff in a field is necessary to realize some of the benefits of strip till.

The report she co-wrote states that growers are concerned that areas with little residue will be droughty and more susceptible to weed growth, while areas with heavy residue may have more fertilizer and herbicide binding, and more soil-borne disease pressure under cooler moisture conditions.

“It’s a matter of finding the optimum level for your area,” she says.

Shanking nitrogen improves yield

The study also examined nitrogen fertilizer application rates and methods.

Generally, N that was broadcasted vs. shanked significantly lowered the number of beet plants per acre and the yield.

“It is possible that the concentrated fertilizer in broadcasted urea granules may cause seedling burn,” Moore says.

The report adds that growers should be cautious of shanking or broadcasting N at high rates (140 pounds per acre or greater) on areas with residue cover of 5 tons per acre or greater.

“We saw dramatic yield losses in these scenarios, possibly due to seedling burn and root stunting,” Moore says.

Waggener writes from Laramie, Wyo.

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FROM FIELD TO LAB: University of Idaho Extension soil specialist Amber Moore and other scientists have determined that the amount of residue cover in strip-till sugarbeet fields and the method and rate of nitrogen application can impact beet yields.

This article published in the August, 2012 edition of WESTERN FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2012.