Draft Prediction of Commonly Used Tillage Implements for Sandy Clay Loam Soil in India

Abstract

Draft requirements for prototypes of mouldboard plough, cultivator and offset disc harrow with different widths of cut or number of tools were measured at four levels of depth and four levels of forward speed in three soil compaction levels in a soil bin with sandy clay loam soil at an average soil moisture content of 9.58% (d.b.). Effect of depth was more significant on draft of mouldboard plough and offset disc harrow, whereas number of tynes was the most significant factor for cultivator. Rate of increase of draft with respect to depth was higher as compared to forward speed, cone index and width of cut for all implements tested. Draft values predicted by ASABE model were compared with those obtained from soil bin tests at three compaction levels. Quite often, the measured draft values were found to be about 2.9, 1.7 and 1.65 times more than the ASABE predicted values for mouldboard plough, cultivator and offset disk harrow, respectively. An equation similar to the ASABE model incorporating cone index was developed using stepwise regression analyses to model the draft of tillage implements for the range of soil and operating condition tested. Field tests with commercial models of these implements were conducted to acquire data for draft by developing appropriate instrumentation to validate the developed draft equation. The average absolute variations between the predicted and measured values of draft were within 5.5 % and 11.6% for all the implements tested, and thus validated the developed draft prediction equation.