We will explore the interaction between water stress and mechanical impedance on plant growth in soils of different structure, mineralogy and management history. We will also explore how root activity changes the soil environment and determine the effect of root activity on the relative magnitude of different physical stresses at a given soil water status. We will also determine how changes in soil structure due to root activity affect the hydraulic and mechanical properties of soil. This will provide collaboration opportunities within WP3 to examine the effects of root stress on nutrient acquisition and cycling and with WP4 to understand the effects changes in soil structure at a larger scale, and with WP5 to understand how soil structure affects microbiological function.

A significant contribution of this WP will be to the understanding of the temporal dynamics of soil structure in the rhizosphere that occur as a result of soil drying to potentials less negative than the wilting point. Access to the long term experiments at Rothamsted and soils of different texture and organic matter content provide an opportunity to approach this problem systematically.