http://extension.colostate.edu/topic-areas/agriculture/irrigation-scheduling-the-water-balance-approach-4-707/

Regards

Please shed a bit more on the design, are the pipe vertical and perforated and to what depth, do you have water in the pipe? what devices do you have for soil water measurements. 

Sir, my experiment is in 1500 m2, I can not shed. The length of perforated pipes are 10,15,20,25 cm in different plot and I have installed tensiometer, in all plots for measuring the soil water potential.

Ok if you have installed tensiometers at different depths which I suppose one or two be below the maximum rooting depth of rice at maturity. You will monitor the soil water potential profiles regularly during the rice growth period till maturity/harvest. You need to measure also the soil moisture profiles at the same time you are measuring soil water potential profiles at corresponding soil depths. These 2 sets of data soil water potential and soil moisture profiles will provide you good data to calculate the soil water balance for the root-zone. However if you do not have soil moisture profiles, you can determine the soil moisture characteristic of the soil to establish the relationship between soil moisture and soil water potential using e.g. the van Genuchten equation (1980), you can use Rosetta or RETC Software or use any non-linear curve fitting approach to fit this equation and determine curve fitting parameters. Using this equation, you can convert your soil water potential into soil moisture data. Using this data you can solve the soil water balance equation. Will check for typical such examples... 

Thank you very much for given me your precious time sir. I will again concern you to discuss about my experiment.