Portable technology used to evaluate soil fertility

Frances Gould, Benedict, Linda F., Morgan, Johnny W.  |  11/11/2013 9:12:58 PM

Beatrix Haggard, LSU AgCenter agronomist, explains a scanning device to analyze plant tissue to determine nutrient needs. She said the price, more than $30,000, means the gadget will be used mainly by consultants and researchers.(Photo by Linda Foster Benedict)

Portable X-ray fluorescence spectrometry is normally a process used by those in the metal industry, but an AgCenter study is using the equipment to look at fertility issues in corn and soybeans.

LSU AgCenter soil specialist Beatrix Haggard is taking samples of young corn and soybean plants as a first step in calibrating this portable equipment to correspond to results from the equipment in labs on the LSU AgCenter campus in Baton Rouge.

"What we’re doing is looking at how we can get vital information to growers in a matter of minutes that currently can take up to a month," she said.

This year most of the work involved gathering data for calibration so she can be sure the field results correspond to the lab findings, she said. "This is the first year of what will probably be a four-year study."

The machine uses X-rays to scan plant samples, and the color of the reflected light indicates the amount of the elements being analyzed.

"Soil scientists have been using this technology for the past 10 years in soil," Haggard said. "They have been using it for environmental remediation; looking at heavy metals like arsenic and lead in the soil."

This machine has never been used with plants, she said, but it is commonly used in steel manufacturing to look at impurities in metals like gold and silver.

"Some dried, ground plant samples have been scanned," she said. "But not fresh, green samples from the field." This is why this first year of the study will require extensive calibration.

When plant samples are sent to the lab, they are dried, ground and then analyzed. This has to be taken into account when analyzing fresh samples in the field because of the moisture differential.

"You get different variations by slight amounts, so we’re trying to correct for that," she said.

The equipment used in the study is not something that the average farmer will go out and buy because the price is prohibitive, Haggard said. "At $37,000 per unit, this will more than likely be something that would be used by LSU AgCenter specialists and crop consultants."

The analysis will allow growers to know immediately what may be wrong with plants and what needs to be done to correct the problem.

Haggard said the key to the process is to get the analyses done while the plants are young so fertilizer applications can be made in time to improve yields of the current crop instead of providing information for the next year, as the situation is now.

"This is the first step in this study," Haggard said. "The second part of the research is looking at a variable-rate application for residual nitrogen across soil types.

Johnny Morgan

(This article was published in the 2013 Soybean and Grain Research & Promotion Board Report.)

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