Database Research Summaries
2018 Impact of Best Water Management on Soil/Water Quality and Soybean Production

calendar_today Year of Research: 2018
update Posted On: 12/06/2019
group Xinhua Jia (Principal Investigator, North Dakota Soybean Council)
bookmark North Dakota Soybean Council

Research Focus

The focus of this project is to study the impact of drainage water management  and sub-irrigation on soil/water quality and crop yields in the Red River Valley.


  • Evaluate water quality differences among different drainage water management (DWM) practices (surface drainage, tile drainage with gravity outlet, tile drainage with flow control, and sub-irrigation) using measurable parameters, including nutrients and salt contents in surface and subsurface outflow.
  • Measure the soil chemistry changes due to DWM and sub-irrigation (SI) practices via soil sampling and analysis around the tile drains.
  • Assess the DWM and SI impacts on crop yield through vegetative index and soil salinity mapping (SBARE).


  1. Six farm fields were used–four in Clay County, MN, and two in Richland County, ND, to monitor the nutrients and salts coming out from tile drainage outlets. The nutrients and salts in the six fields were checked and their changes were compared due to tile drainage. Crop yields were also compared in the six fields to better evaluate the tile drainage impact.
  2. Results indicated that nitrate nitrogen concentration in the tile drainage water (6.23 ppm) was five times higher than that in the surface drainage ditches (1.16 ppm).
  3. Higher amount of salts were found in tile drainage flows, when compared to the surface ditch water. With good water management practices in the field, the nitrate and salts can be retained in the field in late spring and summer, and improve the water quality in the surface water environment.
  4. The soil salinity changes were monitored in the field using soil sampling and salinity maps. Results clearly indicated that soil salinity was reduced with tile drainage. Soil sampling around the tile drains, however, indicated soil salinity had increased in one location, probably due to over irrigation.


Soybean growers will benefit on how to manage drainage water to reduce detrimental effects on the environment.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.