Using one's sense of touch to test the moisture of potting compost is not a good indicator of when plants need to be watered. The MLT tensiometer from the Irrometer Company is a very sensitive instrument that operates at very low water holding capacity soils (coarse sand) and non-soil potting mixes used in the container industry - where soil moisture tension (SMT) needs to be maintained in the 5-15 centibar range with some precision. The instrument is available as a manual gauge or as a remote sensing unit that can be connected to any computerised system. As water is removed from the substrate by the plant (or by evaporation) the SMT increases. By experimenting with a given crop and substrate, the MLT tensiometer provides a grower with a standard measurement which can be translated into sub-optimal moisture levels (at which point plants should be watered), and a danger level beyond which plants will start to wilt and pass beyond recovery. This simple instrument substitutes guess work. The instrument consists of a tube with a ceramic tip that is placed into the substrate at the level where most of the roots are. The attached gauge registers all the suction exerted on it. A range of different versions is available for application in other sectors such as landscaping and for agriculture in general. Fax 001 9096893706 www.irrometer.com