Soil physical properties and root dynamics as affected by tillage and water regimes in rice cultivation

The sustainability of rice production in traditional ways under intensive puddled condition is increasingly threatened due to fresh water scarcity and soil degradation by intensive puddling in many areas. Repeatedly imposing wetting and drying cycle and conservation tillage can improve soil physical environment and root growth. This study investigated the combined impacts of alternate wetting and drying (AWD) irrigation and reduced tillage on the physico-chemical properties, root growth dynamics and yield of rice. A field experiment was conducted with two water regimes- continuously flooded (CF) and AWD; and three tillage intensities- conventional, reduced and zero tillage. A rice variety BRRI Dhan 87 was grown. Different root parameters and yield parameters were measured. Soil physical changes and nutrient availability were determined. The root length (20%), root dry mass (70%) and yield (20%) were significantly greater in reduced tillage compared to zero tillage. However, there was no yield difference in conventional and reduced tillage. The penetration resistance of soil was not differed between AWD and CF treatment with similar yield. The nitrogen content in soil (0.30%) and plant (2.93%) was greater in AWD fields with reduced tillage than CF system. The results of this study suggested that combination of AWD and reduced tillage improved soil structure and nutrient availability which positively influenced yield of rice.