How much of your applied nitrogen was used by the corn, or not-used by the corn and may still remain in the soil? If any remains, the rain you are hoping for may leach the N out of the soil and it is lost to you. Many producers will be planting a cover crop this fall to collect the N and recycle it to the next crop when the cover crop is plowed under. Nafziger says the soybeans following corn will use the nutrient, but he said it is hard to determine what left over nitrogen will be hanging around for use by second year corn. That is supported by University of Wisconsin research (pdf), which addresses cover crops after a drought, “One benefit of planting cover crops after corn silage, small grain, or a processing vegetable crop, or after a manure application is that the cover crop can take up residual nitrate and reduce the risk of nitrate leaching between harvest and planting. Other benefits of cover crops include reduction in soil erosion and weed suppression.” While one federal program to finance cover crop planting expired last week, others have been announced, which may be available at FSA or NRCS offices.

There are myriad cover crops, from grasses that establish quickly and trap nitrates to brassicas, such as radishes, turnips and other that have other benefits. The N taken up by a cover crop is cycled back into the soil during the decomposition of the plant biomass. The release of N into the soil is, in-part, a function of the carbon to nitrogen (C:N) ratio of the plant material, according to the Wisconsin research. For more information about planting cover crops and their benefits, consult the Midwest Cover Crop Council.