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Salinization severely affected a soybean production field near Grand Forks, ND in 2018 due to a persistently high water table. Most of the field had substantial crop loss, whereas the southeast corner sustained healthy soybean growth. This corner with healthy soybeans marked the location of a previous research project that was managed with cover crops, no-tillage and tile drainage that had been decommissioned three years prior. This stark observation presented an opportunity for us to better understand what aspects of soil health and management prior management practices govern resiliency to future soil salinization. This is a great importance for soybean, since they are sensitive to soil salinity.

This project’s goals and objectives were to:
1) Determine why some soil management practices build a soil’s resiliency to salinization using this field as a case-study.
2) Identify soil health parameters linked to soil management areas demonstrating notable resiliency to soil salinization and soybean loss.
3) Use these data to inform recommendations to soybean growers with fields vulnerable to soil salinization.

Soil samples were obtained along transects in 2019 that extended from areas of dead, damaged, or dying plants into areas with living and thriving plants. Transects were placed in various locations that reflected current and prior soil management practices including tillage, cover crops, and subsurface drainage. Soil samples were then evaluated for their fertility, aggregation, and biological communities.

None of the measured soil properties appears to provide adequate information to infer if a soil may be prone to salinization. The outcome of salinization was clearly observed at this site with distinct boundaries (within a few inches) between areas with dead plants as compared to areas with living plants. Visually, soil management zones provided stark evidence that the combination of no-till and subsurface drainage made a positive difference in salinization and crop survival. However, areas with the same or contrasting management histories had the same trends in soil properties. We recommend that producers focus management efforts on soil processes, such as residue cover to limit evaporation and subsurface drainage to maintain lower water tables, as opposed to targeting preexisting soil health properties. This case study demonstrates that the combination of no-till with subsurface drainage can provide crop protection from salinization due to shallow saline water tables.

Results and project updates were presented at the Dakota Innovation Research Technology (DIRT) Workshop, Conservation Tillage Conference, and the international ASA-CSSA-SSSA conference in the winter of 2019-2020.