Effect of method and times of puddling on some soil physical properties and rice grain yield

To optimize the puddling operation in paddy land preparation، the effects of puddling methods and times on some soil physical properties and grain yield and yield components of rice variety Hashemi were evaluated in this research. The experiments were conducted in a split block design in three replications with two factors، puddling method in four levels (power tiller conventional puddler، power tiller rotary puddler، power tiller cono-puddler and tractor-mounted rotivator) and puddling times in four levels (from once to fourth) in a silty clay soil. Results revealed that the minimum bulk density (0. 801 g. cm-3) and maximum penetration depth of falling cone (13. 31 cm)، weeding efficiency (60. 57 %) and puddling index (54. 53 %) was related to puddling with tractor-mounted rotivator and the maximum bulk density (0. 872 g. cm-3) and the minimum of weeding efficiency and puddling index (51. 52 and 44. 50 %، respectively) was belonged to power tiller conventional puddler. Increasing of puddling times from once to fourth، decreased the bulk density from 0. 882 to 0. 795 g. cm-3، but increased the penetration depth of falling cone from 9. 04 to 12. 39 cm and also weeding efficiency and puddling index from 51. 78 to 56. 54% and from 45. 21 to 51. 23 %، respectively. The grain yield in puddling with tractor-mounted rotavator and power tiller rotary puddler (3429 and 3401 kg. ha-1، respectively) were significantly (P<0. 01) higher than those of power tiller conventional puddler and power tiller cono-puddler (3346 and 3332 kg. ha-1، respectively). The grain yield increased from 3322 to 3408 kg. ha-1 with the increasing of puddling times from once to fourth، however there were no significant differences between twice، thrice and fourth puddling. In total، results of this research revealed that twice puddling with power tiller rotary puddler or tractor-mounted rotavator can be considered as a proper treatment for puddling operation in silty clay soils similar to experimental site.