Leaching a concern if and when drought lets up
The director of the Iowa Nutrient Research Center is concerned history will repeat itself after the drought subsides.
Matt Helmers says a lot of leaching occurred when a return to more normal precipitation followed extreme dryness in 2012.
“In 2013 we saw an increase in nitrate concentration from about 12 or 13 (percent) the previous few years up to over 21 post those dry conditions of 2012. And we’re kind of in some similar conditions now.”
For most of the Western Corn Belt, he tells Brownfield there hasn’t been much water moving through the soil profile below the plant root zone in over a year.
“And in some cases we might have some reduced crop yields, and so all those factors end up that we have likely quite a bit of residual nitrate within the soil profile susceptible to leaching losses once we do get precipitation.”
Helmers says data following the 2012 drought shows cover crops can effectively reduce loss by taking up residual nitrate.