Effects of PTO-powered disk tilling on some physical properties of Bangkok clay soil

Abstract

Experiments were conducted to investigate the effects of tilling with a PTO-powered disk tiller on some physical properties of Bangkok clay soil. Tests were conducted at 1, 2, 3, 4 and 5 km h −1 forward speeds and 28° and 33° gang angles. Average moisture content of the soil was 26 g 100g −1. The effects of disk tilling were assessed in terms of changes in bulk density, total porosity, cone index, clod size distribution and soil inversion during the first and second passes. Tests were also conducted in the unpowered mode at a 28° disk gang angle setting during a single pass. The study revealed that the bulk density and cone index were reduced, and the total porosity, content of clods of < 15 mm diameter and soil inversion were increased with an increase in the number of passes and forward speed. At any given pass and forward speed, the reduction in bulk density and cone index, and increase in total porosity and content of clods of < 15 mm diameter, were greater at a 28° disk gang angle setting compared with a 33° setting. More soil inversion was recorded at a 33° than at 28° gang angle setting. A comparison of performance between powered and unpowered modes revealed that, in the unpowered mode, the tilling effects on soil physical properties were less than that obtained in the powered mode.