Soil fertility studies aim to save farmers money

Frances Gould, Schultz, Bruce  |  10/22/2014 12:07:52 AM

Autumn Acree, an undergraduate summer intern, scans ground corn leaves with the X-ray fluorescence device to evaluate the status of elements in the plant. (Photo by Beatrix Haggard)

Close-up of the screen of the X-ray fluorescence reader.(Photo by Beatrix Haggard)

LSU AgCenter soil specialist Beatrix Haggard is working on soil fertility projects to help corn and soybean farmers determine the nutrient levels they need for their crops.

She is looking at soil nitrogen levels on-farm to see if the element moves down within the top 2 feet of soil after heavy winter rainfall. Her study focuses on fields where soybeans have been followed by corn and on fields where corn is grown continuously.

She expects that nitrogen levels will be higher in fields where soybeans are grown because of soybeans’ nitrogen-fixing capability and ability to break down at a faster rate.

Haggard is also evaluating the use of enhanced-efficiency nitrogen fertilizers.

"These products help to slow the transition of nitrogen into forms that are more prone to loss in the soil system," she said. "They are being evaluated for both liquid urea ammonium nitrate and urea in corn production systems on Sharkey and Gigger soils."

The project also is investigating the use of a handheld X-ray fluorescence device that can measure levels of micronutrients – including potassium, manganese, zinc and iron – in living plant material in the field. "We’re still in the early stages of that work," she said.

The readings from the device are being compared to the results of laboratory analyses of plant tissue to get a more accurate determination of the nutrient levels. Eventually, she said, the device could be used as a diagnostic tool to scan a field and map nutrient deficiencies.

"Our hope is we can catch problems early enough in the season so nutrients could be applied at the critical stage of a plant’s growth," Haggard said.

A second project is looking at the optimum use of potassium fertilizer.

A large-scale on-farm test is in its first year in corn on a Caddo Parish farm. A similar trial was evaluated in Tensas Parish in 2013. Yields will be compared at zero, 60 and 120 pounds of potassium per acre, she said.

At the Macon Ridge Research Station, different potassium rates are being used on research plots for soybeans and corn, and the applications are being made in fall and spring to see if the seasonal difference affects a crop.

Potassium also moves through the soil, she said, so the project should reveal the extent of movement. Soil samples are being taken before fertilizer is applied for both the fall and spring treatments. Bruce Schultz

This article was published in the 2014 Louisiana Soybean & Grain Research & Promotion Board Report.

 

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