Trial Type
Soil Health (Tillage, Residue Management., Cover Crops)
General Stats
Soil Stats
Methodology
Salt affected soils are a problem in South Dakota. 7.5 million (M) of SD’s 49 M acres are impacted by salts. Salt problems are classified as either too much total salts (saline) or too much sodium (sodic). Seed germination is hindered in both saline and sodic soils. Sodic soils face the additional problem of erosion use the dispersive effects of sodium. One method to remove the salts that SD farmers are using is installation of agriculture tile drain. Research objective was to evaluate the functionality of tile to remove salts and, specially sodium from the soil.
Tile was installed in the study field in 2017 fall in a Brown County, SD field with salt affected soils (Figure 1 & 2). Sampling points were established in spring 2018. Four-in diameter soil cores were collected to 3.5 ft deep, tile installation point. Cores were divided horizonal sections and analyzed for total salts and sodium content.
Results
Annual rainfall at this site was 16 and 26 inches in 2018 and 2019, respectively.
At the shoulder position, surface soil (0-3 in), EC and sodium levels were low, EC = 1.9 and 1.8 and 29-38 ppm Na, 2018 and 2019. However even though the corn and soybean yields were not impacted by salts at this location, total salts and sodium increased in the subsurface horizons above and at the tile line.
Progressing down the slope in the field to the backslope position, EC and sodium in the surface soil decreased from 2018 to 2019. However, the EC and Na in the subsoil horizons increased. At the toeslope position, the EC and Na values do not change between years or depths.
These results suggest that salt and specifically Na concentrations have not decreased in the the 2 years that the tile has been installed. Some salts moved out of the surface horizon at the backslope position and may allow for row crop seed germination in years where water table is lower. However, the subsoils still contain significant amounts of sodium and if row crops are planted in these areas, surface salts will return if ground water tables remain high.
