Soil Mechanics Lab

Angeleke Lymberatos and Louis Morgan

The feasibility of growing alfalfa beans in a hydrophilic transparent medium

The third week of working in the soil mechanics lab was certainly challenging- but we made a lot of progress. Several attempts to successfully grow germinating alfalfa seeds in a transparent medium have provided us with valuable feedback. And we made the following inferences from our observations so far

A. Small, narrow container may be better to sustain plant growth in this medium. We have used different sized containers (25x18x18 cm to 7x5.5x9.5 cm) and the plants appear to thrive better in the smaller containers. This may be related to the compactness of the soil- the aquabeads can be compacted better in these small narrow containers. In some cases we added glass marbles to compact the medium even more.

B. The depth of the aquifer is very critical to the plant survival. When the aquifer is too low the plant doesn’t survive. Apparently the plant roots are unable to obtain sufficient quantities of water when in direct contact with the transparent media.

C. The size of the swollen aquabeads was also important as plants thrive better when using smaller beads. This is another important observation as the intact water-infused aquabeads can be up to 1.5 cm in diameter. Most of the aquabeads were used in an intact form in the transparent medium, making these particles somewhat similar to gravel in size (coarse grained) but with a somewhat viscous state. It would be interesting to see where soil engineers would classify these transparent media based on grain size- or Atterberg limits. Maybe we need to crush the aquabeads into particle sizes that better simulate soil particles.

We also germinated some pinto beans and have planted them into the transparent medium. We will see next week if the larger seeds will have a better chance of growing in this media! Otherwise we may need to do further research on soil mechanics on how to create a better simulation of soil!