Improving Irrigation Management By Understanding Rhizosphere Processes.

Roots obtain a growing volume in the soil over the course of the growing season and soil physical properties like soil strength and bulk density directly affect their distribution. It is necessary to know the extent of the root system to effectively irrigate crops. Sensor-based irrigation allows farmers to irrigate when plants become stressed. But it is not clear, in what soil depth the soil matric potential needs to be measured for optimal irrigation performance. The objectives of this project are to determine how irrigation and soil physical properties affects soybean root development and to evaluate performance of soybean cultivars under different irrigation regimes.

Literature shows that more stressed soybean plants produce smaller, more numerous roots while healthier plants produce less, but larger roots. In the past, root analysis has been a destructive process that consisted of taking rooting measurements after uprooting the growing plant. In contrast, mini-rhizotron systems consist of cylindrical cameras that can be used to image plant roots in the soil through acrylic tubes. Their advantages include non-destructive root assessment, measurement of the same roots over time, and evaluation of the root structure and architecture.

In 2016, a first experiment with 5 irrigation treatments (0.0cm, 0.9cm, 1.9cm, 2.9cm, 3.8cm) and 8 cultivars indicated different responses of cultivars to irrigation. This year, the experiment will include irrigation strategies, such as the checkbook method, sensor-based irrigation, and irrigation based on growth stages.