Have you ever wondered why nitrogen is so hard to manage? As you can see in the nitrogen cycle diagram below, the nitrogen that is available to plants is affected by many factors including weather and soils. These factors are complicated, and many are beyond the control of the farmer.
To control the uncertainty created by weather and soils, most farmers and agronomist use a little or sometimes a lot more nitrogen than is needed. Not only is this hard on the pocketbook, but it also causes severe environmental problems. Last year, I attended state level workshops where regulations were discussed to limit these environmental problems. Many of the potential regulations that were discussed would be difficult for farmers to live with.
Recently, there has been a lot of effort made to create new methods of managing nitrogen. Several companies and institutions including Corteva and Cornell (Adapt-N) have created models that model the most important parts of the nitrogen cycle shown above. Models have their place but collecting and integrating real-time data with enough accuracy and resolution is challenging.
For the past several years, we have been working with UNL to develop a method that uses the corn plant as a model. The corn plant is able to collect and analyze nitrogen data in real-time because it integrates actual genetic, environmental, and management factors that affect the nitrogen needs of the plant. We then use imagery to interpret the plant models.
Interpreting what a corn plant says about its nitrogen status versus other stress factors is the main challenge with imagery. The solution deciphered was to use the NDRE crop index (red-edge and near infrared reflectance off the crop canopy) to generate a nitrogen-calibrated sufficiency quantity called the sufficiency index (SI). NDRE is very sensitive to changes in crop nitrogen status and the way the SI is calculated from it allows for proactive recommendations that help you apply N before the crop experiences any stress.
Last fall Jackson Stansell created a business, Sentinel Fertigation, to market and scale up this image-based nitrogen management method. We are offering this method on a limited number of acres at $6.00/acre this year. Our goal is to work with enough farmers that we discover the tangible value and best practices for implementation at production scale.
With the high levels of carryover nitrogen in the soil from last year (due to warm dry weather), this will be a good year to give it a try.
