Minnesota Corn Growers Association
Written by Jonathan Eisenthal
Knowing exactly how much moisture an irrigated farm field needs, and when it needs it, is a surprisingly complicated matter.
With research funded through farmers’ investment in the Minnesota corn check-off, University of Minnesota researcher Vasudha Sharma wants to help farmers improve the accuracy of the tools they use to plan the timing and volume of irrigation.
“Learning what is happening under the ground is so exciting,” said Sharma. “When we see a field, we think, it’s flat and uniform, and a soil sample from anywhere would represent the whole field. But that’s not the case. Everything is different underground. There are so many factors that come into play.”
Sharma, who is an Assistant Extension Professor in the University’s Department of Bioproducts and Biosystems Engineering, is making tests and comparisons in two dimensions of irrigation: improving the accuracy of models that help farmers schedule irrigation, and also testing the relative quality and utility of different moisture sensing equipment. In addition, she is looking at how different methods of scheduling irrigation prevent the wasting of water, and how they can reduce the leaching of nitrates out of the farm field.
Sharma is comparing results at two Minnesota locations: one farm in the Bonanza Valley region near Paynesville, and the other at University research plots in Becker.
The Irrigation Management Assistant Tool is an online irrigation scheduling tool developed in 2015 for use in Otter Tail, Becker, Wadena, Hubbard, and Todd Counties. It takes data like temperature, humidity, winds, solar radiation and rainfall amounts from 12 weather stations in those counties. Sharma is testing the accuracy of the tool, and refining it with more data in the hopes of expanding it and making it available anywhere in Minnesota where farmers irrigate.
Her research compares the Irrigation Management Assistant Tool with the more traditional “Checkbook Method,” which tallies moisture in, versus moisture taken up by the crops, in order to estimate irrigation need. Both tools are water balance models that usually don’t require in-field moisture monitoring. They use weather and crop data to come up with their recommendations.
Sharma compares these two modeling methods to direct moisture sensing. She is looking at the range of equipment available, from the economical Watermark sensors to the more accurate and costly Acclima TDR sensors, to help producers make choices based on their needs.
The data from Sharma’s research is also being incorporated in a more comprehensive planning tool called Environmental Policy Integrated Climate (EPIC) computer model. University of Minnesota Professor David Mulla and his team are working on making this model more accurate by incorporating Sharma’s research data into the model. This model will help accurately quantify crop water consumption and nitrate-leaching losses from agricultural fields on regional scales.
Dr. Sharma is finishing up the second year of the project, and plans to spend the next few months assessing the data in order to publish the results. Because each of the methods offered different irrigation recommendations each growing season, she feels certain that the data will yield useful conclusions.
Sharma’s project is one of many supported by the Minnesota Corn check-off. Through their investment in the check-off, the state’s corn farmers support $2.6 million in research annually. Learn the many ways the check-off is working on your behalf by clicking here.