Research Highlights

Research Highlights
Exploring Tools to Improve Soybean Water Use Efficiency

Large plots under irrigation host trials comparing irrigation timing and other factors to optimize irrigation programs. Data gathered from these trials is helping to create a tool farmers will be able to use for irrigation decisions. Photo: Avat Shekoofa

By Laura Temple

Water often becomes a yield-limiting factor for soybean production. The plants especially need adequate water during pod fill to give the seeds good size and weight. 

“Water is a critical issue for agriculture,” says Avat Shekoofa, a crop physiologist and associate professor of plant sciences for the University of Tennessee Institute of Agriculture. “Farmers need information so they can learn how to help crops use available water as efficiently as possible.” 

Her ongoing research strives to do just that. The Tennessee Soybean Promotion Board invests soy checkoff funds in large plot irrigation research. Previously, her work found that delaying the start of irrigation supports yield and profitability.

As this research continues, Shekoofa and the team are exploring other inputs that could influence water use efficiency. They also are working with economists to develop a decision tool incorporating this data to help farmers determine when to irrigate soybean plants.

Could a Biofungicide Influence Water Use? 

While discussing crops with farmers, Shekoofa constantly listens for new opportunities to improve water use efficiency.

“Some farmers have shared anecdotes about a biofungicide they applied at planting to help with disease control,” she says. “Under drought conditions, they observed improvements in plant growth in rainfed fields where they used this product to manage diseases.”

Large plots under irrigation host trials comparing irrigation timing and other technologies to optimize soybean irrigation programs. In 2023, trials included a biofungicide proven to support corn growth under dry conditions. Photo: Avat Shekoofa

Other research showed that this at-plant fungicide product supported corn growth and yield in dry conditions. Based on these results, Shekoofa added the biofungicide to the soybean irrigation study in 2023 to find out if soybean plants experience a similar result. 

“By mid-season, we saw no significant stand differences,” she reports. “However, we will observe how soybean plants treated with this biofungicide respond under rainfed conditions and the two irrigation regimes in this study.”

As a crop physiologist, she observes how plant growth responds to different environmental factors. She hopes to learn if this input could influence soybeans to reduce water use or allow plants to better take in water. She will also monitor soil moisture as not to overirrigate. At the same time, she will pay attention to season-long disease management.

Decision Support Tool Development

Rainfall, weather conditions, crop rotation, soil moisture and many other factors impact soybean water needs. According to Shekoofa, the research team has gathered this type of information through the large-plot irrigation study since 2017. 

“To make all this data more meaningful and accessible to farmers, we have made notable progress on developing a tool to help farmers decide when to irrigate,” she says.

Building on years of historical weather information, five years of environmental and water data, as well as crop rotation records, they are creating a model to predict soybean water needs. They’ve worked with ag economists to account for not just yield, but system cost, as well. 

“We’ve learned that irrigation can start later and still maintain yields, which saves costs and water, and also limits the over-watering issue,” Shekoofa explains. “Our decision tool will account for these learnings so farmers can irrigate as cost-effectively as possible.”

As the team learns more about other potential ways to improve water use, that data will be incorporated into the decision tool. Soon a test version will be available for farmers.

“We plan to continue gathering data, so that when the tool is ready, farmers can confidently initiate irrigation timing to optimize both soybean yield and profit,” she says.

Published: Oct 30, 2023

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.