Navreet Mahal, a 4th-year PhD student co-majoring in Soil Science and Sustainable Agriculture, had a busy summer conducting corn stalk sap nitrate analyses on seven research sites in Iowa. The main objective of this project was to evaluate a new test to optimize nitrogen fertilizer inputs.
The stalk sap nitrate test can help farmers make in-season decisions about fertilizer application based on the actual nitrate uptake by the plant. Nitrogen fertilizer is commonly over-applied. Most of the nitrogen taken up by corn comes from soil organic matter and the amount available is highly variable from year-to-year and field-to-field. By knowing how much nitrogen the corn can get from soil, farmers can apply the right amount.
Currently the two most common methods used for making decisions about fertilizer application to corn are the late spring soil nitrate test and the end of season corn stalk nitrate test. The soil nitrate test determines soil nitrate content – not plant nutrient status. The corn stalk nitrate test, done at the end of season, does not allow farmers to make decisions early enough to affect yield during the growing season. It is end-of-season evaluation tool. A stalk sap nitrate test, on the other hand, can provide information about the nitrogen status of corn early enough to make appropriate fertilizer decisions.
Navreet’s research is the result of a collaboration with Dr. Liang Dong’s group from the Department of Electrical and Computer Engineering at Iowa State University. Dr. Dong’s group has invented new soil and plant nitrate sensors that enable the new plant and soil tests that Navreet is developing. Such tools will make testing nitrogen status of soil and plant not only faster but also cheaper.
While more research is needed to develop the test, Navreet looks forward to finishing this season’s fieldwork and start preparing for next season. She is excited to be part of this innovative collaboration between Agronomy and Electrical and Computer Engineering departments and she is especially grateful to her co-advisors, Drs. Michael Castellano and Fernando Miguez for providing this opportunity. Her work will be useful for farmers and will have a practical impact on the crop production and the environment.