Optimisation and Modelling of Soil Pulverisation Index Using Response Surface Methodology for Disk Harrow Under Different Operational Conditions

Abstract The study aimed to determine the optimal pulverisation index of soil for disk harrow by modelling. A mathematical model was developed using a Design-Expert software and response surface methodology. Experiments were carried out in silty loamy soil with three different levels of soil moisture content of 9.25%, 17.56%, and 22.32%, operating depths of 10 cm, 15 cm, and 20 cm, and operating speeds of 3.17, 4.85, and 5.47 km·h-1. The quadratic model proposed by the Design-Expert software was statistically significant (P <0.01), with a strong correlation relationship (R2 = 0.989) between actual and predicted soil pulverisation index values. The adequacy precision achieved at 41.84 showed the models‘ ability to navigate the design space. However, statistical analysis, using the t-test and P-value, showed the actual and predicted values have no significant differences in the pulverisation index of soil. The optimal soil pulverisation index (8.61 mm) was achieved with a desirability of 1.00, at a soil moisture content of 14.43%, an operating depth of 11.64 cm, and a forward speed of 5.30 km·h-1. Model validation confirmed acceptability (R2 = 0.974) and a 99% accuracy in predicting the soil pulverisation index.