The measurement and the understanding of water and chemical fluxes in the unsaturated zone pose a challenge today. Several techniques are used at different scales to determine these fluxes. Often there is a lack of precision between measurements made at different scales. Our motivation for this newly proposed session is that during the last couple of years lysimeter technology has made tremendous progress with respect to the accuracy of measurements, instrumentation, data acquisition, and the avoidance of typical lysimeter errors. The best available large lysimeters nowadays are contain undisturbed monoliths, are continuously weighed with high accuracy, have a suction control at the lower boundary, and avoid any island effect by an perfect embedding into the surrounding environment. By that, large lysimeters can nowadays be used as precision measurement tools for validation of many coupled processes like evaporation, transpiration, and solute transport. The session should aim on documenting the state-of-the-art in lysimeter technology. Contributions addressing methods of measurement and their impact on flux determination focussing on lysimeters are also sought. Experimental as well as modeling contributions related to flux determination and interpretation are welcome.