Coefficient Determination of Specific Draft Equation for Moldboard, Disk and Chisel Plows



Drafts of major primary tillage implements were measured in a clay loam soil using a tension loadcell. Implements consisted of a moldboard, a disk and a chisel plow each equipped with one tillage unit. A photoelectric speed sensor was used for actual forward speed measurements. During the study, the effects of forward speed and tillage depth on draft requirements were investigated. A general regression equation was developed to predict the specific draft of these implements as based on the Standard ASAE, D497.5. Results of statistical analysis indicated a significant increase in draft for all the three implements with an increase in depth of operation. The values of specific draft for the three tested tillage implements were significantly affected by forward speed. Coefficients of specific draft equations were determined through regression analysis. Specific draft equation coefficients (A,B and C) were obtained as: 256.26, 2.28 and12.11 from moldboard plow; 152.28, 3.79 and 9.66 for disk plow; and 26.9, 12.18 and 0.13 for chisel plow respectively. High values of R-square (R2) for specific draft equations in the case of each implement showed that the models are able to present a good prediction of the implements' required draft.