Change of soil hardness and soil properties due to tile drainage in the Red River Valley of the North

Abstract

Subsurface drainage (or tile drainage) is expected to expand significantly in the Red River Valley of the North, yet its effects on soil quality have not been studied. The objectives of this project are to evaluate the changes of soil hardness and physical properties overlying tile drained and undrained areas. In 2002, tile was installed in the south half of a 47 ha field located in southeastern North Dakota. During the fall of 2007, after soybeans were harvested, soil borings were taken to a depth of 2.1 m and soil samples collected at intervals of 15 cm. Two soil borings were in the undrained portion of the field and four soil borings were in the tile drained portion of the field. Soil properties were measured to determine if there were differences due to tile drainage. Soil hardness, an indicator of compaction, was measured at the site of each boring. The soil samples, taken from 15 cm increments of the soil borings, were analyzed to determine soil moisture content, texture, bulk density and saturated hydraulic conductivity. There was no significant difference of the soil bulk density, moisture content, and soil texture. However, as expected, there was large variability for each of these parameters. There was no significant difference in the saturated hydraulic conductivity, but there was great variability between increment samples. This may be due to the variability of the soil texture at different depths. Soil hardness was statistically significant only in the 0-15 cm interval (the tillage zone).