Can soil-supplied nitrogen replace fertilizer nitrogen needed for corn?

By Greg LaBarge

In a couple of situations where we plant corn, the soil may already provide some or all the nitrogen (N) the crop needs.  Two common examples include: when an alfalfa crop is terminated after the first cutting, or when manure is applied sometime during the ten months prior to planting corn. Recently, a study from Virginia showed evidence that long-term cover-cropped fields warrant measuring soil N before finalizing the N rate decision. How should we go about determining the final N rate? The best way to answer this question is the use of a Pre-Sidedress Nitrogen Soil Test (PSNT).

However, another test means spending money and time collecting soil. Are the potential savings worth the cost? A few examples may help understand the potential cost savings.

Spring-terminated alfalfa stands: We have two Ohio trials in which corn was planted into alfalfa stands that were three or more years old and terminated after the first cutting.… Continue reading