Soil Testing Critical After A Drought Year

Carryover nitrogen in the soil will be likely; deep soil sample to about 2 feet.

Published on: Oct 4, 2012

Planning for next year may not be at the top of your priority list right now, but as harvest wraps up, soil sampling should be near the top of their list.

"This has been among the most challenging growing seasons in 50 years, with rainfall amounts far below average. Irrigation has moderated drought impacts for many Nebraska growers, but at a significant cost," says Richard Ferguson, University of Nebraska-Lincoln Extension soils specialist. "The combination of drought conditions, heavy irrigation, and widely varying yields means that soil testing is more important than ever this year."

Irrigated corn yields across Nebraska are predicted to be moderately lower, 3-8% below average, while dryland yields will be substantially reduced, from 32 to 67% below average. These estimates are based on weather data from 2012, and assume no yield-limiting factors other than temperature and solar radiation for irrigated production, Ferguson says.

Soil Testing Critical After A Drought Year
Soil Testing Critical After A Drought Year

Many areas of Nebraska had high temperatures during pollination, which may further reduce yield from modeled predictions. The big question is how drought will affect nutrient requirements for next year. The net effect of crop nutrient removal on soil nutrient availability will vary from field to field, and with locations within fields.

For very low-yielding, dryland corn fields, expect residual nitrate levels to be high. This will primarily be from unused fertilizer nitrogen. Soil mineralization of nitrogen will have been quite low in dryland fields due to low moisture. Limited crop nitrogen removal and little or no leaching means that unused nitrogen will remain in the soil.

Soil Testing Critical After A Drought Year
Soil Testing Critical After A Drought Year