MTech.

Water loss by deep percolation constitutes a major part of the total water loss from the rice fields. Puddling is widely carried out in rice field to create favourable soil condition for the growth of rice plant and to reduce the loss of water through percolation. An experiment was conducted in sandy loam soil to determine the effect of different tillage methods on percolation loss of water and to evaluate their effect on grain yield.

The treatments choosen for the study were puddling with power tiller, puddling with tractor cage wheel, puddling with animal drawn puddler (TNAU helical blade type), compaction using roller and puddling with country plough along with planking (control). The experiment was laid out in randomized block design with five replications. Seedlings of short duration rice variety ‘triveni’ were used for transplanting. The daily water loss from the experimental plots was measured using field hook guage. The water loss through percolation was obtained by subtracting the evapotranspiration from the total water requirement.

The mean water requirement was highest in the plots puddle with country plough (1609.3mm) and was lowest in the plots puddled with tractor cage wheel (1510.3mm). The percolated water constitute 62 per cent and 64.34 per cent of the total water requirements in the plots puddled with tractor cage wheel and country plough respectively. The lowest mean percolation of 936.12 mm was recorded in the plots puddle with tractor cage wheel. It was followed by puddling with power tiller (949.92 mm), compaction using roller (966.02mm), puddling with animal drawn puddler (1025.02mm) and puddling with country plough (1035.12mm). However, the treatments did not differ significantly regarding the loss of water through percolation. The percentage variation of the percolated water for the different treatments over the control was maximum (17.66 per cent) during the vegetative phase. The variation from the control decreased during the latter two stages and was minimum during the ripening stage (3.89 per cent). The plots puddle with tractor cage wheel recorded the highest yield (11.26 kg/plot) compared to other treatments. The water use efficiency varied from 15.68 kg/ha-cm (puddling with country plough) to 18.64 kg/ha-cm (puddling with tractor cage wheel). The yield and water use efficiency also did not differ significantly among the treatments. The reason for the insignificant among the treatments regarding the loss of water through percolation, yield and water use efficiency could be attributed to the sandy loam nature of the soil since the response of rice plant to various tillage methods depends up on soil texture. It is known that the surface soil aggregates play a major role in controlling the infiltration rate of soil. Since the soil in the experimental field consists of 10 per cent gravel, 65 per cent sand, 12.5 per cent silt and 12.5 per cent clay, the amount of finer particles available for clogging of pores and surface seal development are less in these type of soil, which might be the reason for the treatments not showing any significant variation in the water loss through percolation. From the study undertaken, it was concluded that different tillage methods have no effect in light textured soil in controlling the loss of water through percolation.