Chlorosis in soybeans
Iron deficiency chlorosis is a serious issue in soybeans and can drastically cut into yields. High soil pH levels set the stage for chlorosis, and high soil moisture levels and high salt concentrations all can make it worse. Under these conditions, soybeans can’t access iron from the soil and the leaves of young plants turn yellow.
You won’t see the chlorosis until the plant reaches the trifoliate stage of growth. And once it’s visible in the leaves, there is no fertilizer you can apply that will bring it back to a lush green and reach its full yield potential.
Dave Franzen is an Extension soil specialist at North Dakota State University. He says everything that you can do to remedy the problem has to be done before planting.
"If the weed pressure isn’t that horrible, planting little bit wider rows is ok but of course we also have to fight the weeds now. Certainly, keeping the seed population higher helps out," says Franzen. "And then, there’s certain kinds of iron fertilizers that can be used with the seed at planting time that have been effective."
Chlorosis isn’t uniform across a field. Even small changes in topography can affect it, so carefully select the area where you plan to plant beans. The seed variety you choose is also very important.
"In areas where this is prevalent, which is certainly eastern North Dakota, northwestern Minnesota, there’s been a lot of effort in the last two decades in screening varieties for chlorosis tolerance and they’ve made great headway," he says. "And so, after field selection, the next thing that the grower needs to do is to check out the tolerance of varieties to this problem."
Work with a trusted crop advisor who has experience with these tolerant varieties.