| dc.description.abstract | The Red River Valley of the North in North Dakota and Minnesota is a region with
unique clay soils. Since 1993, the region has seen increased annual rainfall that has caused
seasonal soil waterlogging, inhibiting crop yield potential. Prolonged waterlogging may
cause debilitating physiological and chemical problems in plants. Subsurface (tile) drainage
is relatively new to the region and offers an option farmers are exploring to help reduce
excess water in the rootzone. The objective of this research was to identify the effect of
subsurface drainage on soybean [Glycine max (L.) Merr.] productivity using various
cultivars and to evaluate differences in soil temperature, soil penetration resistance, and
water table depth between drainage treatments.
Two experiments (2009-2010) were conducted in the Red River Valley. The
experimental area is unique as it has eight tiled units which can each regulate drainage
using control structures. The experimental design was a randomized complete block (RCB)
in a split-plot arrangement with four replicates. The whole plots were drained or undrained
( control structures opened and closed, respectively), and the sub-plots were 29 soybean
cultivars. Soybean cultivars were selected based on iron chlorosis resistance, phytophthora
root rot tolerance, and growing capability in wet soils. Penetrometer readings, water table
depth, and soil temperature were measured weekly.
Soybean yields between drained and undrained treatments were not significantly
different according to the combined analysis. This was due to 2009 being a relatively dry
year and 2010 a relatively wet year. However, in 2010, the non-genetically modified (non-GMO) soybean cultivars and the cultivars chosen for their resistance to Phytophthora sojae
were significantly better on the drained soil. In 2009 and 2010, drained treatments had a
significantly higher soil penetration resistance, indicating that the drained soil is capable of
a higher carrying capacity compared to the undrained soil. The wheat measurement site
had a value of 1,420 k:Pa in the drained soil, while the undrained soil had a value of 1,267
k:Pa. The soybean measurement site had a value of 1,137 kPa in the drained soil, while the
undrained soil had a value of 1,021 k:Pa. Finally, the bare ground measurement site had a
value of 1,077 k:Pa in the drained soil, while the undrained soil had a value of 1,001 k:Pa.
The water table was lower on drained soil compared to the undrained soil early and late in
the growing season, causing the differences in soil penetration resistance. Temperature
was significantly higher only on the drained soil planted to soybean compared to the
undrained soil planted to soybean. The temperature difference was most pronounced in the
spring.
Subsurface drainage is a valuable tool for farmers in the Red River Valley. Despite
the clay soils, cold winter, and shorter growing season, subsurface drainage works and
helps to improve the efficiency of farming large fields in an area that has consistently
battled wet weather for the last ten years. At a time when commodity prices are at a record
high, improving efficiency and productivity with subsurface drainage might be an option.
Overall, tile drainage has the potential to drastically change how farming is conducted in
the clay soils in eastern North Dakota and northwestern Minnesota. | en_US |
