MANAGING SALINITY WITH COVER CROPS: A WHOLE SYSTEM RESPONSE

By Dr. Caley Gasch, NDSU Soil Science - Research; Jason Harmon, NDSU Entomology Department; Dr. Tom DeSutter, NDSU Soil Sciences Department; Dr. Abbey Wick, NDSU Soil Health - Extension Salinity affects about 13% of North Dakota’s land area, and almost every farmer in the state works in fields that have salt patches. These salt patches suffer poor soil health, and many cash crops are not adapted to the salty soils. As a management strategy to improve salty soils, we wanted to try incorporating a cover crop into a corn-soybean rotation. Cereal rye is a nice option because it is popular, it over-winters, and it is more salt-tolerant than corn and soybeans. Our expectation is that the cereal rye will use excess water, improve soil structure, enhance drainage in the salty areas, and ultimately improve the health of the salty soils so that they can support a cash crop. However, we don’t know if adding cereal rye into this system will create problems, such as competition with the cash crop, or by providing habitat for unwanted insect pests. We developed a soybeans won’t grow. Other plant species that are more field study to address these ideas, where we hope to (1) identify if cover crops offer a practical management strategy to improve corn production on salty land and to (2) provide general education and guidance on managing saline soils.

For two years, this study has been monitoring soil properties, plant growth, and insects in four fields that have salt patches (see figures with list of measurements and plot design). The fields are managed for a cornsoybean rotation, and are located near Jamestown, Aneta, and Northwood. In 2017, the Aneta and Northwood fields hosted corn, and in 2018, the Jamestown fields hosted corn. Across each field, we broadcast cereal rye (at 40 lb/ac) into the corn in mid-to late-July, and then terminate it the following spring before planting. Throughout the growing season, we monitor the soils for biological activity and water content, insect abundance and identity, and plant the cereal rye, at the applied rate, does not negatively affect corn growth (in terms of water use, fertility, or diseases and pests). There were no insect pests (such as cutworm) of concern that were associated with the incorporated cereal rye. We also haven’t seen any drastic changes, or improvements in the soil during the first two years of the study. We’ll be watching for the development of soil structure under the cover crop, which is a nice indicator of improved soil health. Unfortunately, the negative impacts of the salts seem to overwhelm any benefit of the cover crop, when applied at the 40 lb/ac rate. Based on these observations, we will be increasing the rye application rate to 80 lb/ac for the next two years of the study to see if a higher rate causes any changes.

We will continue to monitor these fields for another two years, and we will detect any soil structural benefits provided by the cereal rye. Based on these results, we recommend considering a higher rate of rye application, especially in areas where corn and growth.

salt tolerant (such as wheat, barley, or alfalfa) and low input are also options to consider for salty patches. We are confident that by increasing plant activity in saline soils (using salt-tolerant species), we can improve productivity and profitability in those problem areas in the long-run.

This work is ongoing, but our findings so far indicate that Gasch collecting samples for soil health testing