Two lysimeters are described. One has most of the weight of the soil container supported by its buoyancy in water, while the remaining weight is supported by a flexible water-filled bag on which it rests. The other has the whole of the weight of the soil container supported by the water-filled bag. In both instruments changes in weight of the soil container are measured as changes in water pressure in the bag. The lysimeters respond readily to weight changes equivalent to o -oi in. of water on an area equal to that of the surface of the contained soil, and variations due to temperature changes can easily be allowed for. The apparatus is simple and easy to build, free from the danger of leaks, and transportable. The components used are cheap and readily available, so that it is practicable to install a number of instruments for adequate replication in detailed studies of water use by crops under a variety of conditions. This has not usually been possible with existing lysimeter installations, mainly because of their cost.