Puddling and its effect on soil physical properties and growth of rice and post rice crops: A review

Puddling is an important operation of wetland rice cultivation which facilitates transplanting, weed control and reduces percolation loss of water and nutrients. However, besides these advantages, the puddling creates soil physical condition detrimental to post rice crops. The puddling index (%) of rice soils increased significantly over farmers practice when puddling was done by mechanical puddling implements. The bulk densities (Mg/m3) of surface layers were comparatively higher than the sub-surface layer irrespective of different tillage treatments for puddled rice cultivation. The percent distribution of water stable aggregates (WSA) in various size fraction increased with decreasing size range and the Saturated hydraulic conductivity (Ks) of surface soil measured at harvest of rice crop was significantly reduced by tillage. Increased intensity of puddling increased significantly the depth of puddled layers and crack dimensions however puddling reduced both seepage plus percolation loss of water. The dry matter yield (g/m2) and grain yield (kg/ha) of rice increased with increase in puddling intensity. Rice yields were highest under the traditional puddling techniques using draught animal traction but puddling with a rototiller reduced yield because of insufficient depth of puddling. The dry cultivation may have reduced yield due to increased soil strength of the puddled layer and both are thought to limit root development. The grain yield of rice over the years under no-till mechanical transplanted rice (MTR) was higher than conventional puddled transplant rice (CPTR). The yields of post rice crops are usually very low and well below the potential yield which is commonly associated with the adverse effect of soil physical conditions induced by puddling during land preparation for the rice crop. Root growth into the subsoil is generally limited, resulting in low plant available water for post-rice crops.