How better metrics, efficient hybrids could improve Nitrogen management with Dr. Ignacio Ciampitti
The perplexing and important problem of Nitrogen management in agriculture has attracted some of the brightest minds to the field of agronomy. Dr. Ciampitti, a professor in Kansas State University’s Department of Agronomy, is one of them.
During an academic career that has spanned nearly two decades, Ciampitti has focused his efforts on integrating field, statistics, remote sensing and modeling research for understanding plant responses. He has authored or co-authored close to 200 refereed journal articles in the last 10 years and currently oversees a lab of graduate students, post-doctoral researchers, and research staff.
Ciampitti shared some of his recent research on Nitrogen management in corn at the University of Nebraska—Lincoln’s Nitrogen Use Efficiency workshop held in early August. Ciampitti shares a similar mission with Sentinel Fertigation: he’s passionate about developing new tools and strategies to help producers use Nitrogen more efficiently to improve environmental stewardship and profitability.
Nitrogen is essential for healthy crop growth and is often one of the costliest inputs for farmers each growing season. But the Nitrogen cycle is complex and poses management challenges, with applied Nitrogen being easily lost in the soil.
Improving Nitrogen management may start with rethinking the way Nitrogen use is measured.
Shifting the framework
For years, Nitrogen Use Efficiency (NUE) has been a primary metric for determining how well corn plants are using the nitrogen fertilizer that is applied. Ciampitti is an advocate for an alternate framework: Nitrogen Nutrition Index (NNI). Although not as prominent perhaps as NUE, NNI has been a useful metric for several decades.
In simple terms, NUE is the ratio of the crop yield to the total input of nitrogen fertilizer. It’s a metric that only provides a limited understanding, very “static” in nature or not good for representing a dynamic biological system, according to Ciampitti.
“... (With NUE) you’re only calculating that one plant is growing more than the other one and that one plant is producing more yield than the other one with a fertilizer N input,” Ciampitti said.
While NUE can be helpful, Ciampitti argues that NNI, which compares current Nitrogen in the plant to what the plant needs to maximize growth, is a more nuanced metric that accounts for various hybrids and management practices. NNI is calculated as the measured N concentration divided by the predicted N critical, ranging from 0.30 to 1.35.
“If you are below number one, you are not maximizing growth so are under deficiency,” Ciampitti said. “If you are above one, you are basically taking up more nitrogen than you need to maximize growth, luxury N uptake.”
By using a more accurate metric in NNI, Ciampitti believes growers can be more precise with their in-season Nitrogen application.
One limitation of NNI, like NUE, is that it is unable to determine the optimal nitrogen content in the plant if other yield-limiting factors are present. Additionally, quantification of NNI requires in-season leaf tissue sampling which is expensive on a per-sample basis and doesn’t allow for a high-frequency or high-resolution measurement of corn nitrogen status. Remote sensing techniques, such as satellite imagery, offer the ability to quantify crop nitrogen status accurately with less labor, higher spatial throughput, and more frequency.
Sentinel Fertigation’s N-Time™ Fertigation Management System is leveraging satellite imagery to monitor crops, provide near-daily nitrogen status updates, and make regular recommendations as to whether the crop would benefit from additional fertilizer. Critically, Sentinel Fertigation’s image analysis algorithms isolate crop nitrogen needs to keep nitrogen applications in balance with other nutrient availability using patent-pending indicator block technology. Integration of this technology with more efficient hybrids to make smarter mid- and late-season nitrogen application decisions offers significant potential for optimizing applied nitrogen to crop nitrogen needs.
A new Nitrogen efficient hybrid emerges
Ciampitti also champions investigation (in collaboration with seed industry partners) of new corn hybrids that use Nitrogen more robustly.
For the past two years, Ciampitti has been conducting research on a new maize hybrid that has yet to be released on the commercial market. The hybrid trait is that the plant enhances N uptake capacity at its vegetative 11 stage allowing the plant to store excess Nitrogen in its leaves (lower part of the canopy). His research team’s focus centered on understanding if the hybrid was doing that and if the Nitrogen taken up during the vegetative phase helped plant resiliency and ultimately final yield. The results of the research are promising.
“What we have seen is the process we have been able to document is around v10 and v12, that plant becomes more efficient in capturing and taking up nitrogen from the soil,” Ciampitti said.
The plant can remobilize the Nitrogen in those lower leaves later in the season. Nitrogen remobilization is “extremely important” to the develop of corn plants, Ciampitti said. Remobilization is when Nitrogen taken up by the plant earlier in the season is moved from lower leaves to upper leaves and the seed. The slight yellowing of a corn plant’s lower leaves indicates that Nitrogen remobilization is underway.
“... That plant puts Nitrogen in the lower portions of the plant, lower leaves, basically uses this Nitrogen as a reservoir,” Ciampitti said. “This Nitrogen basically remobilizes after reproductive stage to flowering, goes to satisfy the demand from the kernels and then kind of improves the amount of Nitrogen that is available to maintain that Nitrogen demand after flowering. And this is being translated in many situations into having a positive impact on yields.”
The hybrid tested by the seed industry partner in multiple environments presented a high probability to increase yields.
Visual provided by Ciampitti Lab.
Research conducted by Ciampitti and others has shown that corn plants are effective at remobilizing Nitrogen.
“The amount of Nitrogen (a plant takes up before) flowering and the remobilization is usually highly correlated, which basically is telling us, at least the way we’re thinking, that corn plants are really good in some way to create and to store Nitrogen,” he said.
But Ciampitti says it’s not just critical that remobilization happens, but that it happens at the right time.
“We don’t want a plant to remobilize the Nitrogen immediately after flowering because we want to make sure the plant maintains the greenness and the productivity of the canopy, the plant health,” he said.
Ciampitti’s lab is continuing to study how corn intakes, stores and uses Nitrogen. He believes that the research will have impacts on the thinking behind late-season Nitrogen application.
For more information on the research being conducted through Ciampitti’s lab, visit ciampittilab.wixsite.com and you can follow more updates on his team at Twitter @CiampittiLab.