Ideally leaching experiments conducted in columns are of very limited value. And these is particularly so when one tries to simulate puddling in columns. To my mind, no can simulate puddling in columns. If you are using a typical fine textured rice soil in the column and you have filled the column after drying and grinding the soil, you can expect no water movement. Try filling the column as closely as possible as undisturbed soil profile and then try the leaching experiment. Good luck.
I agree to the suggestion by Dr. Bijay Singh. It is very common that leaching is difficulty through disturbed fine textured soil columns. Even for such soils, undisturbed core must be very carefully drawn to have leaching. We faced this problem frequently.
yes I have tried the above mentioned protocol. Using undisturbed puddled soil from paddy field for soil column experiment but still facing the problem. no water movement, no leaching even after 1 week. may be due to the compaction, it change the transport behavior of soil column.
Another to be tried may draw undisturbed soil sores as per study requirement from a dry field, the operate for puddling as done under field conditions or as per the convention of the area. But I do not know whether time will allow you to practice this method.
As a rule of thumb, column percolation tests are not applicable for soils exhibiting a low permeability (kf < 10-6 m/s) which applies frequently to e.g. clayey soils. Typical problems with such soils in column test are clogging, preferential flow, ruptures in the soil or even cracking of the column, mostly independent of disturbed or undisturbed condition of the sample.
Depending on the aim of the experiments, a solution may be to add inert and blank free quartz sand to support percolation in tests using disturbed samples (we have good experiences using 50 % addition of sand with a particle size between 0.6 to 1.2 mm). You have to relate the liquid-to-solid ratio then only to the mass of the sample under investigation.