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Research was conducted on the three dominant agricultural soils of southeast Nigeria to develop some empirical regression relationships for predicting the performances of some selected tractor-hitched tillage implements from the experimental results obtained in the field. Results of the experiments revealed that the optimum speed of plough in clay-loam and loamy – sandy soil was 6km/h with corresponding field efficiencies of 88.11% and 87.55% respectively, while in sandy – clay soil, the plough recorded its optimum speed of 7km/h with field efficiency of 87.78%.The optimum speed of harrow in clay-loam soil was 8km/h with field efficiency of 87.98%. In loamy – sandy soil, its optimum speed was 8km/h with field efficiency of 87.19%; while in sandy – clay soil; it recorded optimum speed of 9km/h with field efficiency of 98.54%. The optimum speed of ridger was 9km/h for all the soils with corresponding field efficiencies of 87.96%, 87.95%, and 89.09% respectively, for clay-loam, loamy-sandy and sandy – clay soil. * Corresponding Author. E-mail. odumaoke@gmail.com Oduma et al.: Simple Regression Relationship.../Agr. Eng. (2020/1). 51-64 52 The optimum speed of rotovator was also 9km/hr in all the soils with corresponding field efficiencies of 89.81%, 87.11%, and 89.40% in clay-loam, loamy-sandy and sandy –clay soil, respectively. These field efficiencies experimentally obtained in the field were compared with the efficiencies obtained from the regression equations using percentage error and the accuracy of the predictions were tested using error root mean square. The comparison of the predicted results with the experimental results revealed that the regression equations broadly did not over or underpredict the experimental results, thus, the prediction errors were within allowable range of ±5%. The coefficient of determination, R 2 for the regression equations developed for predicting the various performance indicators of the tractor – hitched implements vary from 0.7 to 0.9 which show that the variables tested were highly correlated and also an indication that the regression equations were adequate for predicting the performance of the implements.

Simple regression relationships for assessing the performances of selected tillage implements in South-East, Nigeria