Operational performance of crop residue cutting discs in the no-tillage system

Abstract

The objective of this study was to evaluate the operating performance of crop residue cutting discs with distinct cutting edges in the no-tillage system, in relation to the travel speed of the tractor/tool holder set. The experiment was carried out in an experimental area, the soil classified as Paleudalf. The experiment consisted in a factorial arrangement of 4x4, totaling 16 combinations of treatments and three replications, composed by the interaction of the factors: crop residue cutting discs (plain flat disc, wavy disc, rippled disc, and helical wavy disc coulter) and travel speed (1.11; 1.67; 2.22 and 2.78 m s^-1). It was used a mobile tool holder structure for the coupling of the active organs, which was pulled by a farm tractor. For the collection of data on traction force and hourly fuel consumption, it was used electronic instrumentation; as for the measurement of the soil mobilization variables, it was used a microprofilometer. The cutting disc factor showed significant influence on all the variables. The travel speed factor only did not provide significant difference for mobilized soil area. The average requirement of traction demand for the wavy disc, rippled disc, helical wavy disc coulter and plain flat disc was 1.35, 1.27, 1.25 and 1.15 kN, respectively, being increased with the increase in speed. The use of discs with edges that provide larger contact area with the soil, in addition to increasing the traction force demand, makes the process more sensitive to sudden increases in speed, possibly caused by soil impositions. The wavy cutting disc showed the highest hourly fuel consumption. As for the mobilized soil area, it was proven the greater mobilization (42.84 cm²) for the wavy disc and the lowest (20.62 cm²) for the plain flat disc. For all the variables in the study, the highest values were obtained when using the wavy cutting disc and the lowest values when the plain flat cutting disc was used.