Making “SENSE” of Sustainable Nitrogen Management

In today’s world it could be easy to think that the idea of “sustainability” is a new concept.  After all, it’s been just in the last couple years that we’ve seen an influx in advertisements and product labels carrying such phrases as “Produced Sustainably” or “Sustainably Sourced”.  But what exactly does sustainability mean?  While the exact definition is often up for debate and may vary between groups, commonly referenced principles of sustainability within agriculture include:

• Maintaining or increasing production using fewer inputs
• Adopting strategies or developing new practices that lessen environmental impact
• Seeking continuous improvement in agricultural productivity across the entire supply chain   

These principles are far from being new concepts to Nebraska’s corn farmers who understand that “sustainability” is more than merely a marketing term.  As stewards of the land, sustainability is a necessity for farmers to meet the increasing food, fiber, and fuel needs of a growing world, while preserving resources for all uses and to be enjoyed by future generations.

While principles of sustainability are not new to farmers, there is always room to improve on what is already being done through new and innovative methods.  This is what researchers at the University of Nebraska – Lincoln (UNL) hope to achieve with Project SENSE.

Project SENSE, or Sensors for Efficient Nitrogen Use and Stewardship of the Environment, is a research project conducted by UNL in partnership with 5 Nebraska Natural Resource Districts (NRDs) and the Nebraska Corn Board.  Project SENSE seeks to increase nitrogen use efficiency in corn production and reduce environmental impact of nitrogen use on groundwater quality by utilizing crop canopy sensors. 

Nitrogen is one of the most important elements for plants, and successful nitrogen management is critically important in optimizing crop yields.  Although nitrogen is naturally found in air and soil, it’s generally in a form that is not directly available to most plants, or not available in the amount that plants need.  Farmers are able to get around this by applying the usable form of nitrogen (nitrate or ammonium) to their fields – an added input expense that doesn’t come without its challenges. 

Two of the biggest challenges a farmer faces are determining the timing of the nitrogen application and the rate to be applied.  Nitrogen applied too early holds the risk of being lost through leaching before the crop takes it up.  Leaching occurs because nitrate is not held well by soil and therefore can be washed below the root zone of plants especially after large rains.  The ideal time to apply nitrogen fertilizer is during the growing season, just before the crop’s maximum demand for nitrogen.  However, waiting too long to apply runs the risk of logistic or weather conditions not allowing application when planned.  In addition, due to nitrogen’s complex behavior of changing between forms and being highly mobile in soil, soil testing for available nitrogen may give a reading that is only valid at the time of testing, leading to application rate recommendations that may be too high or too low for the plant’s needs.    

A key component of Project SENSE is the use of crop canopy sensors to mitigate these challenges.  The sensors are installed on high clearance equipment which allows for application of nitrogen fertilizer during the growing season of corn when nitrogen is most needed and taken up by the plant.  The sensors themselves measure light reflectance off canopy leaves which correlates to the nitrogen status of the crop and is used to generate real-time optimal rates of nitrogen to be applied as the farmer drives through the field.

In terms of sustainability, the ability to apply the optimal amount of nitrogen at the right time clearly has the potential to lessen the environmental impact caused by nitrogen leaching.  However, Project SENSE also demonstrates an often overlooked component of sustainability – economic sustainability.  If a production practice can’t be sustained financially, it won’t be adopted by producers.  The use of sensors to generate the economic optimum rate aims to achieve stable or increased yields while also using less fertilizer, resulting in increased profit.   

In 2015, 17 Nebraska On-Farm Research Network grower sites were implemented as part of the project, and preliminary results are promising.  At each site, the study compared the grower’s normal nitrogen management approach to the Project SENSE nitrogen management approach.  Over all sites combined, Project SENSE resulted in a reduction of nitrogen by 40 lbs/ac compared to the grower’s nitrogen management approach.  Although an average yield loss of 5 bushels per acre was also observed with Project SENSE, the economic savings from the reduced nitrogen application translated to a marginal net return of $7.75 per acre above that achieved using the growers’ standard nitrogen management practices. 

Project SENSE does more than just demonstrate the potential for improved nitrogen use efficiency using sensor-based application, it also challenges farmers to think about nitrogen management differently and encourage the adoption of strategies that are both environmentally and economically beneficial.  In terms of seeking continuous improvement to enhance the sustainability in agriculture production, Project SENSE is one example of how corn checkoff funds are supporting research to meet the challenges faced by Nebraska‘s corn farmers.  

Watch the video below or click here for a 360 experience of Project SENSE from inside the applicator cab...
*Tilt or drag to move around!*

For more on Project SENSE and to see full results, visit Nebraska On-Farm Research Network at http://cropwatch.unl.edu/farmresearch