Influence of multiple passes and speed ratios of rotary tillage on soil physical properties

摘要

A study was conducted to evaluate the effect of multiple passes and different speed ratios of rotary tillage implements on physical properties of sandy loam and sandy clay loam soil (at moisture content of 9.86 % d.b). The soil bulk density, cone index and soil mean weight diameter decreased after the rotary tillage treatments were applied. The bulk density and cone index reduction was higher under vertical rotary ploughing than in rotary tilling irrespective of soil type. The lower bulk densities of 1.337 Mgm3and 1.342Mgm~3; 1.285Mgm~3and 1.32Mgm~3were observed in vertical rotary ploughing at 10cm and 20cm depths under sandy loam and sandy clay loam soil, respectively. The minimum cone index of 0.382MPa, 0.747 MPa, and 1.325MPa; 0.246MPa, 0.685MPa and1.032MPa were observed after vertical rotary ploughing at 5cm, 10cm and 15cm depths for sandy loam and sandy clay loam soil, respectively. The minimum mean weight diameter of 4.97mm and 5.4mm were obtained under vertical rotary ploughing for sandy loamand sandy clay loam soil, respectively. The structure index values of 1.61 and 1.43; 1.426 and 1.324 were obtained for sandy loam and sandy clay loam soils under vertical rotary ploughing and rotary tilling, respectively. Hence, in the view of thorough soil pulverization and cost economics, two passes of rotary tilling at lower speed ratio (12), or vertical rotary ploughing at lower speed ratios (17 and 12) may be considered as optimum range of operational variables.