Water Percolation Dynamics as Influenced by Submergence Levels and Depth of Puddling in Rice Fields

The water percolation dynamics, as mean infiltration rate has been expressed in terms of an ANOVA model with the main additive components being depth of puddling, submergence levels, days after puddling and their interactions. After testing the adequacy of various components the model has been further modified so that it consists of only the main factors (apart from the residual) which account for 88.2 per cent of the total variation. All the interactions between these factors were not significant. The depth of puddling seems to be the most important, as it alone decreased the infiltration rate by 61.7 per cent. Of this a 53.3 per cent decrease was effected by puddling (at any depth). A further 46.7 per cent decrease was due to changing the depths of puddling from 10 to 20 cm. The exponential relationships of mean in filtration rate with the levels of these main factors have been obtained after first ruling out the possibility of linear relationships. Over 97 per cent adequate exponential relationships were obtained and the appropriate tests of significance of regression coefficients have been carried out. For a unit increase in the depth of puddling the mean infiltration rate was found to decrease significantly at the rate of 4.5 per cent. Oil the other hand. the unit increase in submergence level caused an increase in percolation rate to the extent of 3.1 per cent which of fset the reduction in percolation achieved by the depth of puddling. However, this of fset was balanced by the progress of the days after puddling. A progress of unit day decreases the percolation rate atJ highly significant rate of 2.2 per cent.