Data underlying the publication: Maize root system responses in column experiments to different levels of a compacted subsoil layer

Our study focused on gaining insight in root development (growth, morphology), influenced by the compaction rate of a soil layer. By imposing drought stress in the soil layer above the compacted soil layer it was hypothesized that roots needed to penetrate the compacted soil layer to access water in the deeper, wetter soil layer. We used soil columns consisting of three sections: non-compacted soil in the upper and lower sections and various levels of a compacted middle section. The initial amount of water in the upper soil layer was just enough for plant growth until the moment the roots reached the depth of the compacted soil layer.  No watering from the topsoil of the columns was performed during the entire experiment. In search for water the roots had to penetrate the compacted soil layer to reach the well-watered bottom soil layer. There were no limitations for oxygen and nutrients as the soil was relatively dry and ample nutrients were present in the water used. The main driving force thus was the limitation of water in the upper soil layer. The aim of this study was to determine the impact of different levels of soil compaction in the middle section on shoot and
root biomass, root-to-shoot ratio, root diameter and root length density of a maize plant during vegetative growth under these controlled conditions.