Preliminary Study for the Development of Variable-Tillage Implements for Precision Farming

Using power harrows, soil cloddiness can be altered by adjusting the velocity ratio (λ) of the machinery, calculated from the ratio of the peripheral speed of the tine rotors and the advancing speed. This study aims to gain a greater understanding of soil structure and crop emergence in relationship with the energy needs of the power harrow in various settings. Field tests were conducted on a 5 m working width power harrow coupled with a 230 kW CVT tractor. Tests were performed at constant λ, in particular four different configurations (named Cλ1-4) were performed varying the tractor speed and the tines rotational speed. Through the tractor Controlled Area Network (CAN) SAE J1939 diagnostic port and a datalogger, its speed, engine power, engine speed, fuel rate consumption, and PTO speed were recorded during the tests. In addition, load pins and a torque meter were used to measure the draught force and PTO torque that the power harrow absorbed. Following harrowing, soil samples were sieved, and then granulometric parameters were calculated. Thereafter, the field was sown with maize maintaining constant planter set up all over the field. Then, the crop emergence and phenological stage were manually monitored in the field after few days by counting the number of plants and the number of unfolded leaves respectively. The infield measurements were repeated three times in each parcel. Then, data from tractor-power harrow system, soil granulometry and crop emergence were correlated to find any possible relationship. According to the findings, λ alone does not give useful information on fuel consumption, soil particle size and crop emergence, but it is also necessary to consider the values of forward speed and tine rotational speed with which the parameter was obtained. The results presented in this paper will be useful for the development of new variable-rate tillage implements.