COMPARISON OF TILLAGE SYSTEMS FOR PRIMARY PLOWING IN SUGARCANE CULTIVATION IN THAILAND

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1 1 COMPARISON OF TILLAGE SYSTEMS FOR PRIMARY PLOWING IN SUGARCANE CULTIVATION IN THAILAND Khwantri Saengprachatanarug a and Saree wongpichet a a Department of Agricultural Engineering,Faculty of Engineering, Khonkaen University, 123 Naimaung, Maung, Khonkaen, 40002, Thailand khwantri@kku.ac.th, serwong@kku.ac.th Abstract The sugarcane cane germinates and glows during dry season (Dec.-Mar.) depending on moisture retention in soil. This study aims to develop the prototype of the un-root tillage plough for sugarcane cultivation and evaluate it under sandy soil and heavy clay condition. The first system used the specific developed plough, while the second system used the trash elimination disk plough and 7-disk harrow which is Thai farmer's common practice. The field tests were done to collect and compare the physical properties of soil, field capacity, draft force, and operation cost of each system. The results show that; the soil after using first system had the higher specific retention than that of the second system for both sandy soil field and heavy clay field for all measured depth. The first system had the higher field capacity and higher field efficiency than the second system by 1.19 acre/day and 1.09% respectively for the sandy soil field, lower by 1.56 acre/day and 1.57% respectively for the heavy clay field. Moreover, the first system had 469 USD/yr lower cost than the second system for sandy soil field, but had 33 USD/yr higher cost than the second system for the heavy clay field. Keywords: specific retention of soil, primary tillage, field capacity, draft force 1. Introduction Sugarcane is an important economic crop of Thailand. Referring to reports, there are approximately 1.62 million ha in Thailand, with an average yield of tons/ha and total sugarcane production of million tons (OCSB, 2014). A major problem for sugarcane cultivation is the shortage of labor, especially in the soil preparation and planting seasons (Tangwongkit et.al, 2003). Since the sugarcane cane germinates and glows during dry season (Dec.- Mar.) depending on moisture retention in soil, the tillage process is the first important process to increase yield. The main obstacle of primary tillage, which is called un-root process among farmers, in sugarcane field, is sugarcane leaves and sugarcane top that left covering the soil surface. Due to the dry weather, the decomposition of these residuals was very slow (Tangwongkit et.al, 2003). Hence, a "trash elimination disk plough" was invented in 1999 and has been widely used in primary tillage for sugarcane by Thai farmer until now (Sugarcane support division 4, 2014). However, the soil clod and sugarcane stump after using this kind of plough still have large sizes, the seven disk harrow was commonly used to chop the soil clod and sugarcane stump after the un-root process. At present, as the labor cost was raised, most of farmers have to bear a very expensive cost in order to finish soil preparation and plantation in time, otherwise they need to delay the planting (Garrison et al., 2000). Thus, the prototype of the un-root tillage plough was designed with the attempt to decrease time and labors consumed in this un-root process. This study aims to develop the The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the International Society for Terrain Vehicle Systems (ISTVS), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ISTVS editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ISTVS meeting paper. EXAMPLE: Author's Last Name, Initials Title of Presentation. The 13th ISTVS European Conference, Rome, Italy. For information about securing permission to reprint or reproduce a technical presentation, please contact ISTVS at (72 Lyme Road, Hanover, NH USA)

2 2 prototype of the un-root tillage plough for sugarcane cultivation and evaluate it under sandy soil and heavy clay condition. 2. Materials and method The un-root tillage plough (Fig. 1(a)) was designed to equip through a 3-points hitch to the 80 hp tractor, which is the common tractor size in Thailand. The machine consisted of 4 disk blades and one flat disk blade. Each blade was connected to the frame by independent liver which pressed by double spring. Thus, each blade can operate vertically independent. Two disk blades facing to the right side of tractor, while the other two disk blades facing to the left side of the tractor. At the first row of ploughing, the disk blades that facing to the left side and the right side making a single furrows by moving soil to the left and the right side of travelling direction respectively. After that, by controlling the left wheel of tractor in the first furrow, the left side disk blade will operate a primary tillage, while the right side disk blade will operate a secondary tillage as they will chopped the soil clod and sugarcane residue that once ploughed by the left side disk blade in the former run of the equipment. The flat disk blade was equipped at the rear for direction control of the plough. The disk angle and tilt angle of the disk blade were set at 38 degree and 24 degree respectively. The trash elimination disk plough (Fig.1 (b)) consisted of 4 disk blade facing the right side and one flat disk blade at the rear. the first and third order disk blade had the disk angle of 28 degree and tilt angle of 8 degree, while the second and forth order disk blade had the disk angle of 38 degree and tilt angle of 27 degree, respectively. The first and third order disk blade was designed to chop and separate the sugarcane residual, so that the second and forth order disk blade can cut into soil surface and turn the soil to cover the residual. Refer to Thai farmer's common practice, after the primary tillage by the trash elimination disk plough; the seven disk harrow was used to chop the soil clod and residual especially the sugarcane stump. Thus, the experiments were set up to compare two tillage system. The first system used the un-root tillage plough, while the second system used the trash elimination disk plough and 7-disk harrow. All equipments in both first and second system were equipped to 100 hp tractor for the experiment. Front Top (a) Un-root tillage plough (b) Trash elimination disk plough (c) Seven disk harrow Fig. 1 (a) Un-root tillage plough, (b) Trash elimination disk plough and (c) 7 disk harrow

3 3 2.1 Soil physical properties measurement The experiment fields had two locations; the sandy soil field located in Khonkaen province, on the other hand, the heavy clay field located in Chiyabhume province. Each experiment field was divided into 6 plots so that the first and second tillage system can be tested for 3 replications. Thirty sample of soil were taken per experiment plot before and after tillage. The specific retention of soil [% vol.] was measured through the soil sample at 0, 10, and 20 cm depth. Moreover, soil hardness [kgf/cm 2 ], field capacity [%], permanent Wilting Point [%] and bulk density [g/cm 3 ] were measured. After tillage, 100 samples of soil clod were taken per experiment plot. Their diameters were manually measured and recorded. 2.2 Draft measurement The draft measurement system (Fig.2) was equipped with the tractor (6610, Ford, 82 hp) and tested machine to measure draft force in real time. The system consisted of 3-points hitch strain gauge based sensor (Akari et al., 2011), a data logger (NR-500, Keyence co.,ltd, Japan), a computer (eeepcx11, Asus, Taiwan) and a Video camera with GPS logger (Contour+2, Contour co.,ltd, USA). The sample rate of draft force and GPS location was setup equally to 1 Hz. Then the draft forces were plotted with the traveling distance of the machines. Data logger and computer Video camera with GPS logger Draft sensor (3-point hintch) Fig. 2 Draft force measurement during the field test 2.3 The performance test The performance test was done on the same field with the test mentioned above. The times taken in each field activities were collected. Figure 3 shows the schematic of the field which had a field width (, W) and length (, L) of 20 m and 200 m, respectively. The field width was separated into 6 blocks equally for 2 tillage treatments with 3 replications per treatments. Five (5) samples were taken for the forward speed per row, V 0 -V 5, every 20 m at the middle of the field length. The theoretical field capacity, C T, was calculated from the working width of the plough and average speed using Eq.1. The effective field capacity, C ef (ha/hour) and field efficiency, E f (%) were calculated according to Eq. 1 and 2 respectively. Depth was measured at 30 samples per replication. The fuel was filled in tractor fuel tank at indicated level at the beginning of the test and was refilled after each test. Considering the refilled amount of fuel, Fuel consumption (L/acre) was calculated for each replication.

4 4 C T w V 1 Where; w = working width of the plough and V = average plough speed A C ef 2 T Where; A = planting area (acre) and T = total time consumed (8 hours-day) Cef E f C T Where; C ef = Effective field capacity (acre/day) and C T = Theoretical field capacity (acre/day) Fig. 3 Schematic of performance measurements in experiment plots 2.4 Cost assessment According to the record of sugarcane farmer in Thailand (OCSB, 2014), farmer who own 100 hp tractor would planting sugarcane on the average area of 120 acres (300 Rai) per year. Thus, to assess and compare annual cost of two tillage system, the total area of 120 acres was assumed. Fix cost and variable cost were assessed based on ASBE standard D497.4 using the performance measurement results. The purchased price of the un-root tillage plough, the trash elimination disk plough and seven disk plough was 2523 USD, 2226 USD and 1484 USD respectively. The capital recovery factors and shelter costs were calculated for the fix cost, while the fuel costs, labour costs, lubricant costs, consumable parts costs, maintenance costs were calculated for the variable cost. 3. Results and discussion 3.1 Soil physical properties The sandy soil field before tillage had the specific retention of %vol. After tillage, the plot applied with the first system had the higher specific retention than the second system for all measured depths (Fig.4 (a)). On the

5 5 other hand, the heavy clay field before tillage had the specific retention of %vol. The plot applied with the first system also had the higher specific retention than the second system for all measured depths (Fig.4 (b)). The difference between 2 systems was larger in the sandy soil field. Figure 5 and 6 show the example of experiment plot before and after tillage of the sandy soil field and heavy clay field respectively. The physical properties of soil before and after tillage were shown in Table 1. The bulk density of the plot of the first system was lower than that of the second system for the sandy soil field, while there is no significant different between two system in case of heavy clay field. Considering size of soil clods after tillage, the diameters of soil clods after tillage with the first system were slightly smaller than those of the second system. However, for the heavy clay field, the size of soil clod was still large and the operation of disk harrow might be needed. Refer to the results; the first system can create more void in soil especially in sandy soil field. Specific retention S [%vol.] Specific retention S [%vol.] Depth d [cm] Depth d [cm] Un-root tillage plough Trash elimination disk plough No tillage (a) Sandy soil field (b) Heavy clay field Fig. 4. Specific retention of soil at 0-14 cm depth for (a)sandy soil field, (b) heavy clay field (a) Before tillage (b) First system (b) Second system Fig. 5 Sandy soil field before and after tillage

6 6 (a) Before tillage (b) First system (b) Second system Fig. 6 Heavy clay soil field before and after tillage Table 1. Physical properties of soil measured before and after tillage. Before tillage After tillage Soil properties sandy soil field heavy clay field 1st system 2nd system 1st system 2nd system Soil hardness [kgf/cm 2 ] Field capacity [%] Permanent Wilting Point [%] Bulk density [g/cm 3 ] Soil hardness [kgf/cm 2 ] Bulk density [g/cm 3 ] Average clod diameter [mm] Draft force Figure 7(a) and 7(b) show example of the draft force of the tested machines measured during tillage in the sandy soil field and heavy clay field respectively. Fluctuation of draft was observed for all machines. The draft force of the un-root tillage plough and trash eliminate disk plough was fluctuated in the similar range in the sandy soil field, while the un-root tillage plough had higher draft than the trash eliminate disk plough in heavy clay field. Since the heavy clay had the higher soil strength and cohesion than the sandy soil, the wide disk angle of the un-root tillage plough might cause high draft force in this case. Table 2 shows the statistical analysis of draft of all experiments. Table 2. Draft forces of the tested equipments. sandy soil field heavy clay field Draft forces 1st system 2nd system 1st system 2nd system Un-root tillage plough Trash eliminate disk plough 7 disk harrow Un-root tillage plough Trash eliminate disk plough 7 disk harrow Average draft [N] 14,641 15,958 8,194 23,688 17,952 11,259 Maximum draft [N] 23,571 28,756 15,336 33,176 29,326 17,817 Minimum draft [N] 1, ,778 4,187 6,823 1,681 Standard deviation[n] 3,254 3,990 2,233 4,438 3,254 1,753

7 7 (a) Force [N] (b) Force [N] 35,000 30,000 25,000 20,000 15,000 10,000 5, ,000 30,000 25,000 20,000 15,000 10,000 5, Distance [m] Unroot-tillage plough Trash eliminate disk plough Seven disk harrow Fig. 7 Example of the draft force of the tested machines measured during tillage in (a) sandy soil field and (b) heavy clay field 3.3 Machine performance Table 3 shows the performance of the first and second tillage system measured from the field tests. The tillage depth of the first and second system was similar for both sandy soil field and heavy clay field. Since Thai farmer commonly works for 8 hours per day, it was used for calculation of the field capacity. For the sandy soil field, the first system had the field capacity of 5.93 acre/day and the field efficiency of 85.16%, while the second system had the field capacity of 4.74 acre/day and the field efficiency of 84.07%. Consequence, the fuel consumption of the first system was lower than that of the second system compliance with lower draft force in this case. The first system had the higher field capacity and higher field efficiency than the second system by 1.19 acre/day and 1.09% respectively for the sandy soil field. On the other hand, for the heavy clay field, the first system had the field capacity of 4.35 acre/day and the field efficiency of 87.07%, while the second system had the field capacity of 5.91 acre/day and the field efficiency of 88.64%. Compliance with higher draft force, the fuel consumption of the first system was higher than that of the second system for heavy clay field. The first system had the lower field capacity and lower field efficiency than the second system by 1.56 acre/day and 1.57% respectively for the heavy clay field.

8 8 Table 3. Performance of the first and second tillage system. Performance sandy soil field heavy clay field 1st system 2nd system 1st system 2nd system Field capacity [acre/day a ] Field efficiency [%] Depth [cm] Fuel consumption [L/acre] a working hour 8 hours per day 3.4 Cost assessment According to the performance results the annual cost of two tillage systems were assessed as shown in Table 4. The annual fix cost of the first system was lower than the second system for both fields. For the sandy soil field, since the first system was operated with the higher field capacity and lower fuel consumption than another system, it had 469 USD lower annual cost than the second system. In contrast, for the heavy clay field, the first system had 33 USD higher annual cost than the second system due to its lower field capacity and higher fuel consumption. Table 4. Cost assessment of the first and second tillage system. Fix cost [USD/year] Variable cost [USD/year] Type sandy soil field heavy clay field 1st system 2nd system 1st system 2nd system Capital recovery factor Shelter Fuel cost Labor cost Lubricant cost Consumable parts Maintenance cost Total [USD/year] 1, , , , Conclusion The prototype of the un-root tillage plough was designed with the attempt to decrease time and labors consumed in the primary tillage of sugarcane fields. The field tests were set up to compare soil physical properties, draft force, performance and annual cost of two tillage system under sandy soil and heavy clay conditions. The first system used the un-root tillage plough, while the second system used the trash elimination disk plough and 7-disk harrow. The results shows that, the first system gave the higher specific retention and the lower bulk density after tillage compare to the second system for both sandy soil field and heavy clay field. However, when considering draft force, performance and annual cost, the first system gave the better results only in the sandy soil field compare to the second system. Thus, it can be concluded that the developed plough was suitable with the sandy soil condition, while needed more improvement to use under heavy clay conditions

9 9 Acknowledgements This study was financially supported by The Thailand research fund and Khon kaen University. The discussions shown in this article belong to the authors, which The Thailand research fund and Khonkaen University do not need to agree with. This study was also supported by Applied Engineering for Important Crops of the North East research group, Khon Kaen University. References ASAE Standard, ASAE D497.4, Agricultural Machinery Management Data. ASAE, St. Joseph, MI, USA. Askari, M., Komarizade, M.H., Nikbakht, A.M., Nobakht, N., Teimourlou, R.F., A novel three-point hitch dynamometer to measure the draft requirement of mounted implements. Research in Agricultural Engineering, 57: Garrison, D.D., Dufrene, E.O., Legendre, B.L., Effect of planting date on yields of sugarcane varieties grown in Louisiana. Abstr. J. Amer. Soc. Sugar Cane Technol. 20:115, Office of the cane and Sugar Board, 2014 [update 2014 Nov 20]. Available from: Sugarcane support divition 4, Sugarcane management manual Tangwongkit, R., Design and development of a no-tilled sugarcane planter model FM.44 (NRCT-KU). Proceedings of 41 th Kasetsart University Annual Conference: Engineering and Architecture (2003)