Draught Prediction of Agricultural Implements using Reference Tillage Tools in Sandy Clay Loam Soil

Abstract

An investigation was carried out to predict the draught requirements of commonly used tillage implements in any field condition from the knowledge of : (i) the draught requirements of reference tillage tools in a reference soil condition; and (ii) the scale factors related to soil properties and implement geometry. In the first step, the draught requirements of three different reference tillage tools: (1) a plough with a width of cut of 0·1 m; (2) a tine with a width of cut of 0·075 m and (3) a disc with a diameter of 0·3 m were verified in the soil bin by operating in a reference soil condition (sandy clay loam soil with average cone penetration resistance of 472 kPa and bulk density of 1170±20 kg/m3) at three depths (0·05, 0·075 and 0·1 m) and four speeds (1·2, 2·2, 3·2 and 4·2 km/h). In the second step, the draught requirements of six different scale-model implements: two mouldboard ploughs (0·15 and 0·25 m width); two cultivators (2 and 3 tine); and two disc gangs (0·34 and 0·37 m width) were measured in the same soil with five different soil conditions (average cone penetration resistance and the corresponding bulk density varied from 470 to 1420 kPa and 1170 to 1680 kg/m3, respectively) at particular depth (0·075 m) and speed of operation (3·2 km/h). The empirical equations for draught requirements of reference tillage tools and hence, scale-model implements were developed using orthogonal and multiple regression techniques. The developed empirical equations were verified in the laboratory as well as in the field conditions. A good general agreement between observed and predicted draught values was found with the average absolute variations of 7·0%, 6·2% and 7·5% in the laboratory as compared to 10·6%, 10·2% and 13·2% in the field for the mouldboard plough, cultivator and offset disc harrow respectively. This methodology produced sufficiently accurate results to enable the draught prediction of tillage implements in different soil conditions by testing only the reference tillage tool in the desired soil type at reference soil condition.