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Wet Spring Increases Nitrogen Loss

posted on April 26, 2013


Forecasters are calling for warmer and drier weather this weekend and into next week, offering a welcome reprieve for flood-weary residents – and America’s farmers.

While experts are hesitant to say the drought is “officially” over, mild and dry conditions in the days ahead should allow field work to begin in the Midwest. And some planters likely will run well after dark, until the threat of rain returns late next week.

While planting is at least a couple of weeks behind, cool temperatures and timely April showers have greatly increased soil moisture in much of the Corn Belt.

As usual though, there’s a tradeoff… And believing the rains have washed away precious nutrients, some experts are calling for a thorough examination of nitrogen management plans.

Wet Spring Increases Nitrogen Loss

 Last year, the worst drought in half a century devastated America’s row crops.  Early in 2013, some  believed that dry conditions could continue through this year’s growing season, greatly reducing the amount of nitrogen applied to America’s fields. 

While it is not uncommon for 40 to 50 pounds of nitrogen per acre to carryover from one season to the next, soil samples taken last fall by Iowa State University indicated that some fields could see as much as 100 pounds of carryover. 

However, water samples taken by the Iowa Soybean Association or ISA indicate that wet weather this spring has caused a fair amount of nitrogen loss.

Tony Seeman, Watershed Management Specialist, Iowa Soybean Association:  “We’re seeing a little bit higher concentrations than we typically do primarily related to the drought.  I think it just confirms that leaching is an issue and farmers see it as money going down the river too.  So there might be an opportunity, depending how much it rains between now and planting time, to cut back on rates and save a little bit of money since there is such a bank of nitrogen in the soil.”

 While nitrogen is not usually applied to soybeans, the Iowa Soybean Association does research on corn to provide information to its members who raise both crops in rotation.

Peter Kyveryga, Senior Research Associate, Iowa Soybean Association:  “So the question is if this wet weather continues what is the game plan for the nitrogen management for corn this year.”

 According to USDA, 69 percent of U.S. cropland planted with major field crops --some 167 million acres -- receives commercial and/or manure nitrogen. Corn accounts for 45 percent of U.S. acreage receiving manure and 65 percent of the 8.7 million tons of nitrogen applied by farmers each year.

Peter Kyveryga, Senior Research Associate, Iowa Soybean Association:   “We don’t know what will happen next but definitely it changes the game right now with all the rainfall we’ve gotten over the last 3 or 4 weeks and saturated soil.  Probably we will loose some nitrogen from last year.”

 This season, the Iowa Soybean Association suggests that growers do a late-spring or pre-sidedress soil nitrate analysis in May or early June when corn plants are 6 to 12 inches tall.  The test predicts the amount of nitrogen available before the plants begin intensive uptake of nutrients.  According to the ISA, if the test shows less than 21 parts per million nitrate, the probability is high that the cost of an additional application of nitrogen would be covered through additional yield.     


Tags: corn drought fertilizers Iowa Soybean Association leaching nitrogen soil testing weather