INFLUENCE OF TILLAGE TECHNIQUES AND ORGANIC MATTER ON CARBON AND NITROGEN TRANSFORMATION IN THE RICE RHIZOSPHERE IN AN ALLUVIAL SOIL OF WEST BENGAL

The investigation highlights results of a field experiment conducted in an Inceptisol in the Lower Gangetic Plain of India to evaluate the sole and interactive effect of different degree of puddling through various tillage implements and farm yard manure (FYM) on carbon and nitrogen transformation in the rice rhizosphere over two seasons. Three methods of puddling viz., (1) Light puddling with country plough, (2) Moderate puddling with tractor drawn cultivator and (3) Intensive puddling with power tiller, were employed in specified triplicate plots with and without application of FYM and their effect on organic carbon, microbial biomass carbon, NH4+-N, NO3--N and total nitrogen in the rice rhizosphere soil were assessed. The results of this study revealed that while light puddling induced the highest build up of soil organic carbon, microbial biomass carbon and total nitrogen. Moderate puddling effectuated the highest level of NH4+-N and NO3--N suggesting the highest rate of mineralization of organic-N in rice rhizosphere. Irrespective of puddling intensity, FYM escalated its positive effects. The highest level of NO3--N was induced through the rhizosphere during flowering stage. All the chemical and biochemical attributes of the soil, except NO3 (-) N, were stimulated to the greatest extent during tillering stage. From this research results moderate puddling could be suggested for the best nitrogen availability during the critical growth stages of rice.