Tagged: Nitrogen Use Efficiency
March 29, 2017 at 1:46 pm #892
Hi everyone! I’m Abby Augarten, UW Discovery Farms’ Nitrogen Use Efficiency (NUE) Project Coordinator. Throughout the season, I will be posting updates on the NUE project and reporting on new findings in our data on the WaterWay network. I welcome all questions and encourage comments on NUE and nitrogen management in this discussion forum!
To get us started, here is some background on the NUE project. After completing our second year of the NUE project, we have a dataset of 121 corn grain and silage fields that are representative of Wisconsin’s diverse regions, soils, and farm management styles. NUE assessments assist farmers in evaluating the efficiency of their current nitrogen management practices in order to increase profitability and improve water quality. Looking at a field’s NUE relative to Wisconsin’s range of values helps farmers determine if they can improve their efficiency by altering nitrogen rates, timing or placement.
UW Discovery Farms works with participating farmers to collect data and samples throughout the season. After harvest, all of this data is utilized to calculate our Nitrogen Use Efficiency values and assess how a field’s nitrogen management practices can be further improved.
What do you already know about Nitrogen Use Efficiency and what are some things you would like to learn?
Check back later in the week to read about some of our findings from the 2015-2016 seasons and see what other farmers have to say about NUE!
March 31, 2017 at 9:28 am #902
After conducting two seasons of NUE assessments, UW Discovery Farms has an informative dataset, representative of Wisconsin’s farm systems. As you know, 2015 and 2016 were high yielding seasons. Our data showed yields ranging from 216-246 bu/ac for corn grain and 25-29 ton/ac for corn silage.
Did you witness high yields in 2015 and 2016 and how will this influence your N decisions for 2017?
Click image to enlarge
As you can see in the graphs above, yields were highly variable and did not correlate with an increase in nitrogen supplied. Since the additional nitrogen in higher rates was not realized as additional gains in yield or N removed in the harvest, these fields tended to have relatively lower NUE values. The graph below represents different categories of N rates, and their corresponding yield (blue dots) and percentage of N removed in the harvest (green bars). As nitrogen supplied increased, average yields remained relatively constant and the percentage of nitrogen removed in the harvest (or NUE) decreased.
Click image to enlarge.
Do you think that there is a limit to the amount of N supplied that would result in a yield increase? Or, do you think that these results are specific to high-yielding weather conditions, like those we had in 2015-16?
To read more about our 2015-2016 findings, please find our March 2017 update: “Fine-Tuning Nitrogen Management” (click here!) and visit back on the WaterWay Network!
June 19, 2017 at 9:48 am #1021
Pre-Sidedress Nitrate Test
In a couple of weeks, many farmers will be applying sidedress to their corn fields. As part of the UW Discovery Farms Nitrogen Use Efficiency Project, we run a Pre-Sidedress Nitrate Test (PSNT) on participants’ fields to assess the amount of Plant Available Nitrogen in the top foot of soil. This soil sample is great for any farmer to take on their field; it’s easy and can help determine an appropriate sidedress N rate.
How is it done?
A PSNT sample is best taken 2 weeks before sidedress when the corn is 6-12 inches tall, allowing sufficient time for lab analysis. For one 20 acre area, combine 15 cores (0-1 foot) for one composite soil sample. Keep the samples cold, so that the microbes in the soil won’t continue to mineralize N, and send it off to the lab to be processed. It’s that easy!
A PSNT is incredibly useful, especially for systems that applied manure the previous fall or those that include forage legumes, in order to estimate how much nitrogen was mineralized in the spring. Since N mineralization is highly dependent on weather, relying on book values has its limitations. But a simple Pre-Sidedress Nitrate Test can clarify how much N is available to the plant and what the most appropriate sidedress rate is to increase economic efficiency and reduce the amount of residual N in the soil at the end of the season.
Do you typically take a pre-sidedress soil sample on your farm? Or will you try it out this season? Let us know!
October 19, 2017 at 1:23 pm #1186
Yesterday, Abby and I were in the field doing yield checks and taking harvest samples for the Nitrogen Use Efficiency Project. We are having a great week for field work as I imagine many of you are too!
Share your harvest pictures and stories with us!
November 9, 2017 at 2:26 pm #1195
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