Saline soils, plant growth problems linked to tillage practices

Research on saline soils underway, but at least one cause points to over-tilling

soil tiller equipment for farming

Here in the Red River basin, most fields in crop production are tilled one or more times each year, whether with cultivators, disks or deep tillers. The resulting fields look well cared for — good farming is often associated with well-tilled fields.

In many places in the basin, however, farmers are noticing areas of fields not producing well in recent years.

Could these two phenomena — tilling practices and plant growth problems — be connected?

Turns out the answer is yes. Tilling is a primary way salts trapped in deeper layers of the basin’s soil rise to the surface. The resulting salt-ridden or saline topsoils cause decline — often dramatic — in crop production.

How does tilling cause salts to rise? Well, salts tend to follow water in the soil — they go where the water goes. Tilling causes water to rise in the soil, and the salts rise with the water. Because tilling also dries out the layer(s) of soil it impacts, the salts that have followed the water upwards get stranded in upper layers.

When the phenomenon gets repeated year after year, enough salts make their way up to root level and above to cause loss in the soil’s production capabilities.

And this appears to be what is happening in the basin, where areas of saline soil in crop production fields are increasing with every year. In the North Dakota portion of the Red River basin alone, according to a 2007 mapping, an estimated two million acres have become, or have the potential for becoming, saline.

Once the salts have risen, solutions do not come easily. The movement of salts in the soil can be a complex phenomenon, and, even with best efforts, producers continue to depend on tilling practices. As one researcher from North Dakota State University (NDSU) put it at a recent field demonstration on saline soils, “salinity wipes the easy button off the map.”

Agencies are ramping up efforts to respond to the growing problem of saline soils. For Canadian producers, Manitoba Agriculture, Food and Rural Development is a source of information for managing salinity. For U.S. producers, the Natural Resources Conservation Service offers information, together with technical and financial assistance through its Environmental Quality Incentives Program.

Research on saline soils is also underway. Of particular interest is a long-term study undertaken by NDSU Extension that is applying various practices to saline-impacted soils under real farming conditions in order to keep economics in the equation while improving soil health.

Soil health is also a priority for the Red River Basin Commission (RRBC). A newly established RRBC work group on Soil Conservation/Soil Health has begun tracking and reporting practices from around the basin that further soil health, with the goal of improving soil health in the basin by linking efforts and information.

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