COMPARISON OF SOIL SOLUTION CHEMISTRY IN ZERO TENSION AND CERAMIC-CUP TENSION LYSIMETERS

The chemistry of soil solutions collected from plastic 0-tension and ceramic-cup tension lysimeters was compared. Except for NO3-, there was no systematic difference in the chemistry of major cations, anions, pH or Al speciation of the solutions collected by the two types of lysimeter. Although there were some differences at both 25 and 75 cm depths, on such occasions the difference at the other depth was either in the opposite direction or non-significant. The concentration of NO3- was significantly lower in the 0-tension lysimeters and, although the mechanism is not clearly understood, this may be due to uptake by micro-organisms feeding on fine organic matter particles in these solutions. The choice of lysimeter can be based on the objectives and constraints of the research project, rather than on the fact that the soil solution is more representative with one type of lysimeter than another.