Central Soil Salinity Research Institute, Karnal, Haryana, 132001.
* G.B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U.P., 263145.
Column studies havebeencarriedout with threemodesofleaching, i.e. steady, transient (ponded) and transient (controlled application) simulating three different field situations. In controlled application, 3 cm and 1 cm water has been applied each day. When aimofleachingistoleachdown thesaltswith minimumdrainage volumestransientleaching (controlled application) with application of 3 cm water each day gave the best results. In the simulated conditions of the experiment, reduction in application rate to 1 cm ([1 did not improve leachiJ:lg. In cases where the aim during leaching is to minimize fresh water requirement, then saturated leaching appears to be the best as more salts are leached with equivalent amounts of fresh water applied in saturated than transient (ponded) or in transient (controlled application). For practical applications, it is recommended that initially saline water could be applied to saturate the soil profile which could be followed by application of fresh water. Such applications of saline water could also be made before the onse~ of the monsoon season so as to improve leaching of the profile by the incoming rainfall. Steady state leaching is calculated better by numerical model in which number of soil layers could be varied compared to the analytical solutions of Dieleman or modified BurnS, whue soil profile is assumed to consist of one layer.
Steady and transient leachiflg, saline soils, la~erwise equilibrium theory. conjunctive use, drainage volumes)
