Drained vs. Undrained fields

Thus far we have talked quite a bit about our subirrigated corn fields, but we also have two soybean fields (one that is subsurface drained and one that is undrained) which have provided some interesting comparisons between drained and undrained fields.

Some key points to note about the two soybean fields are:

• Similar soil series amongst two fields
• Same preceding crop (corn)
• Same variety of soybean is grown in both fields
• Relatively same location (two fields are about 1/2 mile apart)

Even though we are still in the process of collecting/analyzing data we can still visually see differences between the subsurface drained and undrained fields.  Below are pictures of the undrained and subsurface drained fields.


Undrained soybean field.  Water logged soils at the beginning of the growing season may have been a contributor to the stunted growth/development of the crop

Subsurface drained soybean field.

 

 

A person can easily see, from the photos, that the subsurface drained crop (bottom photo) is much taller/fuller than the undrained crop (top photo).  Hence, supporting the use of subsurface drainage in the Red River Valley.

Subirrigation

The subirrigation system has been running for almost two weeks and our team is busy attaching various sensors to help estimate irrigation amounts/efficiencies.  The subirrigation system uses the pressure head created in the tank to push the subirrigation water uphill, in the main, and then uses the downhill gradient of the laterals to move the water by gravity.  Below are a couple pictures of the subirrigation system.

Subirrigation system.  Far right- control box, center-tank, left- manifold.

Subirrigation manifold.   The two white PVC lines supply water to two individual sections at the research site.

Thus far, a variable rate current sensor, time-logged cameras, and flow meters (attached to the manifold and individual PVC) have allowed us to better determine when the irrigation system is running, the amount of water being delivered to the system, and the amount of water being delivered to each section of the field.

Below is a picture of a graduate student, Kyle H., preparing a section of PVC, with a pre-attached flow meter, so that we can better estimate the amount of water delivered to a specific section of the field.