Precision farming development centre

A rotary tiller is an agricultural implement, popularly used to reduce the amount of time and labour spent in soil preparation. It can also be used to incorporate residue in a sugarcane field into the soil to increase the organic matter content. However, wear of rotary tiller blades is very high, especially in sandy soil, which significantly affects its working life. The objective of this study was to increase the useful life of the tiller blade in order to reduce the idle time required to replace the blade periodically during soil preparation. The objective was carried out by means of hard coatings, where the effect of the coatings on the wear damage and the wear characteristics of the rotary tiller blades were investigated. This study compared two different thermal spray coatings, namely HVOF-sprayed WC/Co and plasma-sprayed Al2O3–TiO2/NiAl, on carbon steel rotary tiller blades. A test was conducted on a 3.2-ha area of sugarcane field after harvesting. The soil condition during the time of the test was dry, hard and sandy. The test blades were arranged in the tiller using a randomized complete block design pattern to compensate for the blade position sensitivity in order to achieve meaningful data. The test result showed that the average wear rate of the uncoated blades was 0.86 cm3/ha, while those of the WC/Co and the Al2O3 coatings were 0.02 and 0.90, respectively. The wear rates of the WC/Co-coated blades were significantly lower than those of the uncoated blades, indicating a great improvement in the wear protection provided by the coatings. The Al2O3-coated blades, however, did not show superiority over the uncoated reference blades. Some chipping of the Al2O3 coating was observed, which greatly contributed to the high wear rate.

Coordinate transformations were used to simulate the kinematics of a rotary tillage, C type blade. Using three-dimensional computer graphics, a Bezier surface of the rear surface of the blade was generated. The error in generating the surface remained below 1·2, 5 and 8 per cent for the x, y and z coordinates, respectively, joining multiple Bezier surface patches. The analysis was carried out at rotor speeds of 180, 200 and 220 min−1 and at tractor forward speeds of 3, 3·25 and 3·5 km h−1 and for two blade orientations: namely, 0° and 20°. The interaction of the blade with soil during its operation was analysed using a scan of trochoidal paths of the leading and trailing edges of the blade (LT scan) computer programmed in language C/C++. Interference of the trailing edges of the blade with uncut soil was eliminated by design changes and checked with LT scans for the range of selected rotor speeds and forward speeds. The rectified surface was manufactured using high carbon steel.

A minimum tillage technique is required for reducing the labor requirements to prepare a level rice seedbed in Korea. Thus this study was aimed at determining the strip tillage characteristics of rotary tiller blades for use in a dryland direct rice seeder. The experiments were carried out in a laboratory soil bin. The USDA textural classification of the experimental soil was sandy loam. Soil hardness measured by cone penetrometer ranged from 245 to 1442 kPa depending on the depth, and the soil moisture content was 34.6%.The effects of rotary blade shape, rotational direction, number of rotary blades around the periphery, with and without soil-cutting disc blades on soil break up and torque requirements were investigated. Three different types of rotary blade were used, two general purpose rotary blades used with tractors and power tillers, and a leveling rotary blade for tractor use in wetland paddy fields. Rotation in the opposite direction to travel and cutting upwards resulted in soil being scattered out of the seeding furrow. A down-cut process is therefore necessary for effective seedbed preparation of a rice field by strip tillage using a rotary tiller. Of the three types of rotary blade, the rotary blade for the power tiller was considered most satisfactory for strip tillage on a basis of its torque requirement and the ratio of soil breaking. The rotor shaft with four rotary blades had the lowest torque variation and torque requirement and ratio of soil breaking was 24.4%. The width of seedbed prepared by the rotary tiller with four blades during the down-cut process was 80 mm which was enough for direct seeding of rice and applying fertilizer. Though a soil-cutting disc blade helped produce a better seedbed furrow, the increased friction between the disc blade and the soil block generated a much higher torque requirement. The soil-cutting disc blade was not necessary for the strip tillage direct rice seeder. Based on the results a strip tillage technique by the power tiller blade with a down-cut process could be effectively used for a dryland direct rice seeder.

Information is required on power and energy requirements for tillage implements. Draught and energy requirement measurements were made with an instrumented tractor for mouldboard ploughing, disk ploughing, disk harrowing and rotary tilling in the Serdang sandy clay loam soil. The effects of travel speed and tillage depth or rotor speed upon the measured draught and power requirements were investigated. Four polynomial draught and power models from orthogonal regression analyses were formulated based on linear and quadratic functions of travel speed and tillage depth or rotary tiller bite length. The predictions by the draught models developed for the mouldboard plough and the disk harrow were within the ranges of draught recommended by ASAE Standards D497.3. A comparison of the draught model for the disk plough and power model for the rotary tiller with the ASAE Standards D497.3 could not be made simply because these guidelines are not listed therein. Four linear fuel consumption models from regression analyses were also formulated based on drawbar power or PTO power as well as equivalent PTO power. Fuel consumption rates predicted by ASAE Standards D497.3 were found to be 17–33% overestimates of the values predicted by the statistical models developed from measurements. However, fuel consumption rates reported by OECD Tractor Test were found to be 94–109% of the values predicted by the models developed. From 37 to 52% of the measured fuel consumption for the various ploughing operations was required to propel the tractor, and the remainder was used for the actual task of working the soil. Finally, average draught, fuel consumption, wheel slip, drawbar power, tractive efficiency and overall energy efficiency for draught implements as well as average PTO power, fuel consumption, wheel slip, wheel power and specific energy for powered implement are presented. The disk harrow was the most energy efficient implement in terms of fuel consumption and specific energy, followed by the rotary tiller, disk plough and mouldboard plough. These obtained results will be helpful to develop comprehensive information on power and energy requirements of tillage implements for the formulation of Malaysian agricultural machinery management database.

The operation of a power tiller involves walking behind the machine on a tilled or puddle land continuously for hours. Physical efforts required for the operation of the machine combined with exposure to varying degrees of solar radiation, dusty environment, monotonous nature of the job and the severe hand vibrations cause a lot of stress on the operator resulting in physiological and psychological fatigue after the daylong operation. To reduce the time-integrated workload on the operator, administration of a suitable work-rest schedule seems to be a feasible solution. An experiment was therefore, conducted with five subjects to study the influence of four work-rest schedules on physical workload during power tiller operation. Computerized heart rate monitor was used for continuous recording of heart rate data throughout the working day. Psychophysical measurement technique was used to quantify the overall discomfort as well as body part discomfort. The study indicated that the work-rest schedules did influence the physiological and postural workload as evidenced by the differences in working heart rate and postural discomfort. On the basis of the physiological and psychophysical results of the study it was concluded that duration of work bouts during rotatilling operation by power tiller should not exceed 75 min otherwise the operators may develop symptoms of physiological fatigue which may subsequently result in accidents and injury. Work schedules having smaller work bouts involved lower cardiac cost but subjectively felt more fatiguing on the basis of leg discomfort and upper arm discomfort. Rest pauses of 10 min duration were found insufficient for getting recovered from the fatigue developed during the previous work bout. To avoid excessive postural discomfort the minimum duration of rest pauses should be of 15 min. The duration of the lunch break should be more than 45 min and it should preferably be scheduled during the periods of maximum ambient temperature i.e. between 13:00–14:00 h.An appropriate work-rest schedule for power tiller operation may serve as a guideline for making safety standards and norms for power tiller operation and in similar circumstances in other industries.