oontrol, but are of limited value for other agricultural applications, except in sandy soils where the soil-water suction remains within the available range of operation. Another inconvenience of the tensiometer is that it often stimulates root growth in the vicinity of the cup (higher soil-moisture) which decreases the representativeness of the measurement. 2.8.222 The psychrometric method This indirect method of measuring the soil-water potential uses a small chamber of porous material which is buried in the soil. The equilibrium air humidity inside this chamber is taken as a measure for the soil-moisture potential. To obtain the air humidity inside the chamber, Peltier psychrometers are used. (See section 2.2.224) To convert the obtained air humidity values to soil-moisture potential, calibration curves have to be established empirically. As this involves
