Zero-nitrogen test strips evaluate Nitrogen Use Efficiency in corn

Discovery Farms is conducting Nitrogen Use Efficiency (NUE) on-farm research in Pepin, Dunn, and Sauk Counties in 2019.  This is the 5th year of evaluating nitrogen on Wisconsin farm fields, cumulatively now on more than 300 corn grain and silage fields. This field project tracks nitrogen (N) supplied to monitored fields relative to season end crop yield and N at harvest.

Climate, corn yield, and N management all factor into NUE. At the end of the season, participating farmers receive a report with their calculated NUE values. Ultimately, tracking NUE of a farming system will help your agronomy team fine-tune pre-season corn N guidelines and associated best management as you identify N details for realistic yield goals.

Our NUE fields are set up with farmers to include zero-N strips, which helps to consider soil productivity with the background N cycling within the soil compared to the rest of the field with full-rate N and management. For a zero-N strip to be most effective it should not receive any N from fertilizer or manure, aside from starter fertilizer that amounts to less than 30 lbs N/ac.

The included picture looks towards the end of a zero-N strip in mid-July 2019. Here, the whole field received starter fertilizer at planting. That becomes the total applied nutrients the zero-N strip will get. Beyond the orange flags, the farmer broadcast spread the rest of the field to supply the remaining full rate N plus phosphorus, potassium, and sulfur when the corn was 6 inches tall.

By including a zero-N strip farmers can see yield differences compared to full rate N and consider the real efficiency of extra yield achieved with extra N and management applied. We will measure the yield in both the zero-N strip and on a strip where the full rate of N was applied this fall to see if there was a yield increase from the full rate of N and management.

Comparing the yield and N uptake in a zero-N strip, relative to the rest of the field, which had a full N rate, allows the farmer to better understand how much N was supplied by the soil itself given farm management and that season’s weather. A zero-N strip is a good assessment for farmers who are wondering if changes in management (such as planting cover crops, increasing crop residue, reducing tillage) are affecting the soil’s ability to supply N. Additionally they provide a true measure of the economic value of N applied in each year, because they can determine the gain in yield from the N applied.

Another benefit of including zero-N strips within project fields is that it provides farmers with a look at background soil productivity and soil quality. Here is a question to ponder: what can you do within a corn growing season to dial in and capture the best N supply and availability relative to the full management products, rate, timing, placement and technology you use? Through this project, we can provide you with guidance and answers to this question.

Read more about Discovery Farms NUE Project here:

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