Predicting tillage effects on soil physical properties and processes : proceedings of a symposium

The study investigated the performance of three model tillage tools (tines). The experimental tillages were made from flat 8 mm plain carbon steel. They were designated T1, T5, and T20, corresponding to tine widths of 1, 5, and 20 cm respectively. Experiments were carried out in a soil bin filled with sandy clay loam soil at average moisture content 11.5% (dry basis) and 600 kPa average cone index. The plastic limit and liquid limit and plasticity index of the soil are 20%, 31% and 11% respectively. Tests were conducted at forward speeds of 0.28, 1.0, and 2.5 m/s. Depths of operation considered were 35, 70, 150, 200 and 250 mm. Draught measurements were made for the different tines and were also calculated using soil mechanics equation. There was reasonable agreement between measured and predicted draught forces. The effects of depth of operation on draught force of the tines were studied and evaluated. It was observed that draught increased at an increasing rate with depth; the relationship was a curvilinear one best fitted by exponential function. The soil disturbance created as a result was also evaluated and reported in this paper. The parameters used to define soil disturbance of a single tine were: ridge-to-ridge distance (RRD), maximum width of soil cut (WFS), maximum width of soil throw (TDW), after furrow depth (df), height of ridge (hr) and rupture distance ( f ). They all increased as the depth of operation of the tool increased but less proportionately. The critical depth of the tines was also estimated. The results of analysis of variance showed that tool type and operating depth significantly affected draught at 5% level of significance ( p

Performance evaluation of tillage tines operating under different depths in a sandy clay loam soil

Soil bin investigations were carried out to study the influence of some soil parameters
namely: moisture content and cone index, on draught force and soil disturbance of model
tillage tools. The tools were tines in the groups of very narrow tines, narrow tines and wide
tines. The soil under study was a sandy clay loam. It was observed that draught increased at a
decreasing rate as the soil moisture content increased from 11 to 22.5% (db). Polynomial
regression models best described the relationships with high R2 (coefficient of determination)
values. Soil disturbance parameters: ridge-to-ridge distance, width of crescent or width of
furrow at the surface, total disturbed width, height of ridge, and furrow depth were
determined. Tine draught increased at an increasing rate as compaction increased for a cone
index in the range of 150 to 800 kPa with polynomial regression equations best describing the
relationships. The models generated in this study were suitable for predictive purposes.

Draught and Soil Disturbance of Model Tillage Tines Under Varying Soil Parameters

Study the effect of tool geometry and operational conditions on mouldboard plough forces and energy requirement

Fuzzy knowledge-based model for prediction of soil loosening and draft efficiency in tillage.

Very little research has been done to investigate soil loosening as a function of the geometry of the tillage tool and of the original soil properties and moisture content. A field experiment was conducted to observe the effects of the geometric parameters of flat tillage tools on their draft, cutting efficiency and loosening of a moist clay soil. The test tool variables included rake angles to the horizontal of 30, 60 and 90°, widths of 75 and 150 mm and depths of operation of 100, 150 and 200 mm. Measurements were taken of draft, disturbed soil cross sectional profiles and the initial area of soil disturbed by the tools. The resulting draft requirement increased with width, depth and rake angle of the tool. The cross sectional area of soil disturbed did not change appreciably with rake angle, but the significant increase in draft with angle resulted in markedly diminished soil cutting efficiency (area divided by draft). The degree of soil loosening was generally smaller at a rake angle of 60° than at 30 or 90°, and tended to be higher at greater depths of operation. In addition, a larger depth to width ratio generally increased the degree of loosening. Results for the soil studied indicate that the best implement design for low draft, high cutting efficiency and superior soil loosening should have a rake angle of about 30° and should be fairly narrow with a depth to width ratio of 2 or more.

J. Maswaure

Papers

Effect of design parameters of flat tillage tools on loosening of a clay soil