This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Mathematical model-based redesign of chickpea harvester reel
Aim of study: This paper presents a mathematical modeling approach to redesign the reels of chickpea harvesters for harvest efficiency. Area of study: A prototype chickpea harvester was designed and evaluated on the Dooshan farm of the University of Kurdistan, Sanandaj, Iran. Material and methods: The strategy used for reducing harvesting losses derived from the dynamic study of the reel applied to the chickpea harvester. The machine was designed such that bats of a power take-off (PTO)-powered reel, in conjunction with passive fingers, harvest pods from anchored plants and throw the pods into a hopper. The trochoid trajectory of the reel bats concerning reel kinematic index, and plant height and spacing was determined for redesigning the reel. Main results: This kinematic design allowed an estimation of the reel orientation at the time of impact. The experimentally validated model offers an accurate and low computational cost method to redesign harvester reels. Research highlights: The new chickpea harvester implemented with a four fixed-bat reel, a height of 40 cm above the ground for the reel axis, and featuring a kinematic index of 2.4 was capable of harvesting pods with harvesting efficiency of over 70%; a significant improvement in harvesting performance.
Introduction
The nutritional value of legumes was recognized by the 68th general assembly of the United Nations in declaring 2016 as the International Year of Pulses (FAO, 2016). Chickpeas (Cicer arietinum L.) rank third worldwide among pulse crops, accounting for 10.1 million tons annually. India, Pakistan, and Iran are the largest producers with over 70 %, 10 %, and 5 % of total world production, respectively (UCDavice, 2014; Muehlbauer et al., 2017). Small plants with pods close to the ground impede mechanical chickpea harvesting (Haffar et al., 1991; Bansal et al., 1992; Golpira, 2009; Modares Motlagh et al., 2018; Shahbazi, 2018). As chickpeas are becoming more important in the world markets (The Atlantic, 2019), agricultural breeding programs (Grossman et al., 2012; Kanouni et al., 2014; Jayalakshmi, 2016; ICARDA Communication Team, 2019), and efficient harvesting machinery (Dhimate et al., 2018; Singh et al., 2018) would greatly benefit rural chickpea growers who account for almost 50 % of the total production costs for hand harvesting (Haddad et al., 1988). Hand laborers collect the entire chickpea bush into central heaps for transport to a stationary thresher got grain separation (Paulsen et al., 2015). Harvesting the entire plants including roots takes 6 to 8 man-days to harvest 1 ha (Golpira et al., 2013). During hand harvesting, losses can range from 4 % to 15 % (Haddad et al., 1988). Uprooting the bushes removes the nitrogen-fixing bacteria nodules, increases soil erosion, and decreases the following wheat rotation yield.
Pulse harvesting in developed countries is fully mechanized; either by direct combining, or more often, by mowing and swathing followed by combining (Siemens, 2006). Harvesting the seed at 18% moisture content reduces field losses through the combine harvesters (Fleury, 2015). The key to a successful mechanical harvest begins with good weed control to provide a mostly clean and uniform field that is ready for machine harvest. Since chickpea has an indeterminate growth habit, late-season precipitation after initial flowering and seed set can cause the plants to begin to regrow and flower again which complicates mechanical harvesting. In years where there are significant regrowth and flowering, herbicides are sometimes used to terminate the plants to help make it possible to mechanically harvest the seed (McVay, 2019). Desiccants and pre-harvest perennial weed controllers that aid in the preparation for pulses combining are presented by Saskatchewan Pulse Growers (2020). Smart sprayers can reduce the environmentally harmful effect of herbicides (Carballido et al., 2013; Aravind et al., 2017; Saiz-Rubio et al., 2020).
However, the application of grain combine harvesters for harvesting rain-fed chickpeas cultivated in dry or semi drylands were restricted due to high harvesting losses. As stripping only pods can reduce pulse crop losses (Behroozi & Huang, 2002; Sidahmed et al., 2004; Golpira, 2009; McVay, 2019), accompanying passive fingers with bat type reels (Golpira, 2013; Golpira et al., 2013) should increase work quality of chickpea harvesting. A tractor-propelled harvester was fabricated with a semi-mounted chassis in which several bats of a reel, in conjunction with forward-oriented V-shaped slots, detached pods from anchored plants. The crop was conveyed over the f inger and up the platform deck by the reel to the reservoir tank. Equipping the design with air reels (Golpira, 2015; Yavari, 2017; Modares Motlagh et al., 2018; Zobeiri et al., 2020) were reported for increasing harvesting performance. However, in low-density crops, i.e., rain-fed chickpeas, stripper headers cannot produce a continuous f low of material and cause high gathering losses. Table 1 summarizes existing methodologies, that take advantage of reels to guide crop and reduce shattering losses, for chickpea harvesting.
Literature review on the existing mechanism for harvesting rain-fed chickpeas concludes high shattering losses which are the main contribution of the reels. Several research works, e.g. (Oduori et al., 2008, 2012a,b), developed models to study the interactions between the crops i.e., wheat and rice, and a combine harvester reel. A mathematical-based model of soybean harvester reels, which neglects the effects of the number of bats, was presented by Quick (1972). Reel diameter, number of bats, reel angular velocity, reel kinematic index, crop physical characteristics including plant height and distances in rows, and header height were found to be the most design factors affecting harvesting losses (Beard et al., 1992; Sakai et al., 1993; Hirai et al., 2002a,b; 2004), and therefore design parameters for this research.
The objective of this study was to test a prototype tractor-mounted chickpea harvester for harvest efficiency. Mathematical modeling of the reel provided the reel bat trajectory to minimize losses.
Material and methods
Background
Figure 1 pictures an average plant of Kabuli variety and its simplified model. Data was gathered during ten years of measurement on chickpea plants in the field. Harvesting at 5 cm height would theoretically result in zero-remaining pods on anchored plants. In real field evaluations, however, the situation is more complex because it is influenced by the soil preparation system, the crop planting method, and the plant-harvester interaction. The average height of chickpea plants in non-irrigated chickpea fields was 30 cm. The maximum height of plants is important for ensuring that the traveling direction of the harvested material after interacting with the bats is sufficient to carry the harvested material to the hopper.
Reel modeling
Figure 2 is a schematic drawing of the reel components, with the location of the bats, and how the reel diameter was measured. A Cartesian coordinate system was applied to the positive X-axis horizontally to the right and the positive Y-axis vertically directed upward. The peripheral diameter is assumed to be equal to the reel diameter.
Figure 3 shows the hit points of the reel bat for both low and high crops on a vehicle-fixed coordinate system. The forward speed of the harvester does not affect , but it determines the global position (XR, YR) of the vehicle coordinates.
The spatial curve path of the reel bats, as well as the velocities, were employed to design the optimum reel. Using ground-fixed coordinates, the position of any point on the absolute path of the reel bat can be determined according to the following expressions:
in which
and for vertical position, one could write
where XR and YR are positions of bat edge, meter; is the angular velocity of an arm, Rad/s; HR is the height of reel axis above ground, meter; m is the number of bats; and t is time, s. As the number of bats m grows, α decreases (Fig. 4), and therefore α = t/m . For low crops, if the number of bats increases to infinity (m = ∞), the following situation applies:
and
Figure 3 demonstrates equations 3 and 4 are valid if the crop height is more than the height of the reel axis of rota-tion above the ground (h ≥ HR). For short plants and a given harvester, if h < HR, the solution would be YR = h. Figure 4 shows the boundary situation for one bat in which crop height is equal to the position of the reel’s central axis abo-ve the ground. For other cases with a larger number of bats, α depends on h and HR. The situations demonstrated how important bat number (m) was for chickpea detachment by efficiently capturing and drawing them into the conveyor belt, the principal method for reducing yield losses.
The dynamic study of the reel may be expanded if the spacing between consecutive chickpea plants is varied. For example, in the Kurdistan region plant spacing is 50 cm. The time elapsed between two consecutive chickpea plants as the harvester moves at a forward speed V can be calculated from the following equations:
and
where t is the time elapsed between two consecutive chickpea plants when the harvester moves at V speed, s; and α is sweep angle in time t, Rad. The left-hand side of equations 6 and 7 is the same, and hence one has,
To hit each plant at the optimum position, each α re-quires a bat configuration based on the field parameters. At least 2 bats (integer > 1.8) are required for harvesting rain-fed chickpeas spaced at 50 cm, when forward speed is 3 km/h (0.83 m/s), and the reel rotational speed is 55 rpm.
Table 1.The existing mechanisms, concepts, and accessories for chickpea harvesting
Figure 1.EA working model for a chickpea plant that is favorable from the harvesting point of view.
Figure 2.The reel of the developed chickpea harvester with the coordinate reference frame and the parameters relevant to ma-chine design. HR, height of reel axis above the ground; h, plant height; l, distance between two successive plants; R, reel dia-meter; V, tractor forward speed; w, angular velocity of an arm.
Figure 3.Bat hit points for tall plants (a) and short plants (b). XR and YR, coordinates of bat edge; HR, height of reel axis above ground; h, plant height; m, number of bats; t, time; ω, angular velocity of an arm; α, sweep angle.
Prototype chickpea harvester
The tractor-propelled harvester introduced by Golpira (2013) and Golpira et al. (2013) was redesigned concerning reel and its power transmission mechanism. The tractor-propelled harvester was fabricated with a semi-mounted chassis in which several bats of a reel, in conjunction with forward-oriented V-shaped slots, detached the chickpea pods from the bush. The height-adjustable reel delivers the harvested material into the hopper. The main components of this harvester are: a transversely elongated frame fixed to a platform, protruding fingers extending forward over the platform, a reel driving system, a belt-drive, and two pivoting front wheels (Fig. 5). The designed reel consisted of a rotating shaft with rigidly mounted bats on radial arms that pushed the top of the chickpea plants over the platform. The platform design and characteristics described by Golpira & Golpîra (2017). The wooden bats were fixed by bolts on the steel structure of the reel. Two adjustable screws supported two pneumatic wheels which set the working height of the header from 0 to 150 mm. Moreover, these tires guide the platform on ground unevenness to avoid entering stones into the header. Width, length, and height of the machine are 2200, 1000, and 1000 mm, respectively. The working width of the machine is 1400 mm. Additional screws on the reel allowed for further positioning adjustments. The total weight of the machine was 400 kg.
The pulley propelling the reel was located on one end of its rotating shaft, and a tractor-mounted power take-off (PTO) shaft. A gearbox with a conic gear allowed changing the axis direction 90° without modifying the speed ratio was attached to a variable-speed transmission assembly and a V-belt drive connected to the reel, as shown in Fig. 6. This continuously variable transmission system provided a gentle variation in the reel rotational speed with a maximum reduction ratio of 2.1:1. Alternative speed reduction ratios could be produced through the V-belt drive system up to a ratio of 1:5. This transmission reduced the initial 540 rpm supplied by the standard tractor PTO shaft to the 45-110 rpm working interval needed by the reel.
An essential requirement for satisfactory reel performance is that its kinematic index, defined as the ratio of peripheral to forward speed must be greater than one. When the forward speed of the reel is greater than the forward speed of the harvester, the trajectory of the reel is a trochoid (Miller et al., 1990). The kinematic index of the reel was calculated as follows:
where V is the forward speed of harvester, m/s; λ is the kinematic index; n is reel speed, rpm; and R is reel radius, meter.
The chickpea harvester was tested at a fixed ground speed of 3 km/h. The reel was adjusted so that the bats passed approximately 5 cm above the fingers. The reel distance ahead of the finger was fixed at 5 cm. The tilt angle of the platform, i.e. the angle of the platform to with the ground above a horizontal transverse axis, was adjusted to 0°.
Figure 4.Reel bat hit point for tall crops and a large number of bats. A, bat hit point; HR, height of reel axis above ground; h, plant height.
The trials were conducted on the Dooshan farm of the University of Kurdistan (Fig. 7) in July 2017. Cultivated areas of 93,112 ha and 676 ha of rain-fed and irrigated chickpeas in Kurdistan province (34°- 36° N latitude and 45°- 48° E longitude) produced 33,977 and 884 tons/ year, respectively (Ahmadi, 2016; Managing and Planning Institute, 2016). A one-hectare plot was ploughed, disk-harrowed, and sown with the Kabuli chickpea. Plant and row spacing were 50 cm and 50 cm, respectively. The moisture content of the seeds was measured by drying the chickpeas in an oven at 105 °C for 72 hours. The moisture content recorded in harvesting time was approximately between 12 % and 15 %.
The high cost of field evaluations required a simple experimental design. The machine harvested 10 m field runs from three different points. Weeds were removed before the evaluation. Harvesting losses were estimated by collecting the pods and seeds remaining on the ground from a sample area 1.0 m long × 1.0 m (2 rows), wide. For each 10 m run, three samples separated by 2 m were collected. Samples were threshed, cleaned, and weighed to determine an average harvesting loss. Harvested pods were manually removed from the hopper by hand. Plants were manually harvested and threshed to determine harvestable yield for the f ield. Pre-harvest losses, the pods and seeds that fell to the ground before harvesting, were not included in total yield weight in the denominator. Harvester losses were calculated as a percent of harvestable yield by dividing lost seeds by manually harvested yield and multiplying the result by 100. The methodology for determining header losses was described by Paulsen et al. (2014).
Figure 6.Schematic view of the power transmission system including a gearbox, a continuous variable system, and a belt-driven system to provide configurations of reel kinematic index. D, pulley diameter.
Results
Using Eq. (8) with a reel diameter of 0.7 m, a forward speed of 3 km/h, and a reel rotational velocity of 55 rpm, the kinematic index for the reel was 2.4. Figure 8 shows the trajectory of the reel with four fixed bats, a peripheral diameter of 70 cm, and a forward speed of 3 km/h. The arrows in the curve indicate the direction of the moving pods after being hit by reel bats. The critical height for the chickpea plants was about 40 cm to assure the proper rearward velocity for harvested material to reach the harvester hopper.
Figure 9 shows the trajectory of the front point of a bat for a reel with four (m=4) and six (m=6) bats, and a kinematic index of 2.4 (Eq. 3). The trochoid trajectory of a single bat (m=1) reel was also plotted in Fig. 9 for comparison with the other configurations. Considering fixed-bat reels, a harvester speed of 3 km/h, and the corresponding reel index of 2.4, the harvested material is forced in the negative X direction towards the hopper, which only occurred for 4 and 6 bats. Kinematic indices of 1.1 to 3.4 were suggested for a 1.1 m diameter reel operating over a range of ground speeds where an index of 1.25 to 1.5 is recommended for standing crops (Miller et al., 1990).
The reel bats beat the crop at the moment which its velocity vector has a negative X component. The location of this point can be calculated by setting to zero the derivative of equation (1) for t, as given by equation (9):
Substituting Eq. (4) in (2) determines the critical height of 42.7 cm and 41.4 cm above the ground for six and four bats, respectively. At this height, the velocity component of the reel bats in the X direction is zero, which is essential for reels of combine harvesters to reduce shattering losses. The mathematical modeling of the trajectory described by reel bats provided the recommended height of 40 cm above the ground for the reel axis.
Figure 7.Location of the testing fields in the Dooshan farm of the University of Kurdistan.
Figure 8.The trochoid trajectory of the reel with four fixed bats, a peripheral diameter of 70 cm, and a forward speed of 3 km/h.
Figure 9.Trajectories of the reel with six, four, and one bat for a forward speed of 3 km/h and kinematic index of 2.4. The horizontal dashed line shows a plant height of 30 cm, the maximum height of field plants; m, number of bats.
Discussion
Following the successful prototyping of a chickpea harvester by Golpira (2013) and Golpira et al. (2013), this paper aims to derive an experimentally validated model for reel design. The mathematical model representation of the reel bats’ trajectory suggested a height of 40 cm above the ground for the reel axis. Further, the kinematic analysis of the model concerning spacing between consecutive chickpea plants and spatial curve path of the reel bats configured a four-batted design.
Field evaluation of the prototype chickpea harvester confirmed that fixed-bat reel with a kinematic index of 2.4 harvested rain-fed chickpea pods with 71 % yield efficiency. While losses of more than 29% were also reported for the mechanized harvesting of irrigated chickpeas (Haffar et al., 1991; Siemens, 2006; Jayalakshmi, 2016), comparing harvesting losses of rain-fed and irrigated chickpeas does not make sense as there is a significant difference between the crop properties. More precisely, while the prototype chickpea harvester could be used for harvesting both the irrigated and rain-fed farming, the application of the combine harvester is limited to the irrigated chickpeas, due to the plant height. This means that the proposed method in this paper makes a significant contribution over the literature.
Equipping the header with air reels, knife guards, and duck foot fingers, introduced by (Duckfootparts, 2018; Primarysales, 2018; Awsairbar, 2019), together with evaluating of the flexible and height-adjustable reels i.e., 3D Varioflex header (Biso GmbH, 2019; Eggerding, Austria) and D65 draper header (MacDon Industries Ltd., 2019; Manitoba, Canada) is a forward step toward the mechanical harvesting of rain-fed legumes in dry and semi drylands.
The proposed mathematical model-based design of the reel not only reduced the design time and cost, but also increased harvesting performance of the prototype chickpea harvester. The modified tractor-propelled stripper harvester with reel bats and passive fingers effectively stripped chickpea pods from the bushes in the field.
With a forward speed of 3 km/h and a 1.4 m working width, the theoretical field capacity for the prototype harvester is 0.42 ha/h.
References
Ahmadi K, 2016. Agricultural Statistics. Iranian Ministry of Agriculture Jihad, Deputy of Planning and Economic, Center for Information and Communication.https://amar.maj.ir/[In Farsi]
○
Aravind KR, Raja P, Pérez Ruiz M, 2017. Task-based agricultural mobile robots in arable farming: A review. Span J Agric Res 15 (1): e02R01.https://doi.org/10.5424/sjar/2017151-9573
Bansal R, Sakr B, 1992. Development of a vertical conveyor reaper for harvesting chickpeas and lentils in Morocco. Appl Eng Agr 8 (4): 425-428.https://doi.org/10.13031/2013.26087
○
Beard JE, Wright ME, Mailander M, Miller M, 1992. Effects of design parameters on geared two-link mechanisms. Mech Mach Theor 27 (6): 635-644.https://doi.org/10.1016/0094-114X(92)90063-N
○
Behroozi M, Huang B, 2002. Design and development of chickpea combine. Ama-Agr Mech Asia AF 33 (1): 35-38.
○
Biso GmbH, 2019. 3D Varioflex. www.biso.at.
○
Carballido J, Rodríguez-Lizana A, Agüera J, Pérez-Ruiz M, 2013. Field sprayer for inter and intra-row weed control: performance and labor savings. Span J Agric Res 11 (3): 642-651.https://doi.org/10.5424/sjar/2013113-3812
○
Dhimate AS, Dogra B, Dogra R, Reddy BS, Srinivas I, Adake R, 2018. Mechanization in Chickpea Cultivation-Current Scenario and Scope. Agr Eng Today 42 (3): 1-11.
○
Duckfootparts, 2018. Clears the cutter bar to decrease header loss.https://duckfootparts.ca/
○
FAO, 2016. International year of pulses (IYP). Food and Agricultural Organization of the United Nations.http://www.fao.org/pulses-2016/en/
Golpira H, 2009. Determining some mechanical properties of chickpea to use in the design of its harvesting machines. Agri Sci 19 (2): 24-33. [In Farsi].
○
Golpira H, 2013. Conceptual design of a chickpea harvesting header. Span J Agric Res 11 (3): 635-641.https://doi.org/10.5424/sjar/2013113-3728
○
Golpira H, Tavakoli T, Baerdemaeker J, 2013. Design and development of a chickpea stripper harvester. Span J Agric Res 11 (4): 929-934.https://doi.org/10.5424/sjar/2013114-3393
○
Golpira H, 2015. Redesign and evaluation of a chickpea harvester. J Biosyst Eng 40 (2): 102-109.https://doi.org/10.5307/JBE.2015.40.2.102
○
Golpira H, Golpîra H, 2017. Soft simulator for redesigning of a chickpea harvester header. Comput Electron Agric 135: 252-259.https://doi.org/10.1016/j.compag.2017.02.018
○
Grossman JD, Rice KJ, 2012. Evolution of root plasticity responses to variation in soil nutrient distribution and concentration. Evol Appl 5 (8): 850-857.https://doi.org/10.1111/j.1752-4571.2012.00263.x
○
Haddad N, Salkini A, Jagatheeswaran P, Snobar B, 1988. Methods of harvesting pulse crops. In: World crops: Cool season food legumes. Springer, Dordrecht.https://doi.org/10.1007/978-94-009-2764-3_31
○
Haffar L, Singh KB, Birbari W, 1991. Assessment of chickpea (Cicer arietinum) grain quality and losses in direct combine harvesting. T ASAE 34 (1): 9-13.https://doi.org/10.13031/2013.31615
○
Hirai Y, Inoue E, Mori K, Hashiguchi K, 2002a. Investigation of mechanical interaction between a combine harvester reel and crop stalks. Biosyst Eng 83 (3): 307-317.
○
Hirai Y, Inoue E, Mori K, Hashiguchi K, 2002b. Analysis of reaction forces and posture of a bunch of crop stalks during reel operations of a combine harvester. Agr Eng Int: the CIGR Ejournal IV, FP 02 002.
○
Hirai Y, Inoue E, Mori K, Hashiguchi K, 2002a. Investigation of mechanical interaction between a combine harvester reel and crop stalks. Biosyst Eng 83 (3): 307-317.
○
Hirai Y, Inoue E, Mori K, Hashiguchi K, 2002b. Analysis of reaction forces and posture of a bunch of crop stalks during reel operations of a combine harvester. Agr Eng Int: the CIGR Ejournal IV, FP 02 002.
○
Hirai Y, Inoue E, Mori K, 2004. Application of a quasi-static stalk bending analysis to the dynamic response of rice and wheat stalks gathered by a combine harvester reel. Biosyst Eng 88 (3): 281-294.https://doi.org/10.1016/j.biosystemseng.2004.04.010
○
ICARDA Communication Team, 2019. A chickpea revolution in Ethiopia.https://www.icarda.org/media/news/chickpea-revolution-ethiopia
○
Jayalakshmi V, 2016. Machine-harvestable chickpea varieties for a self-sufficient, food and nutrition secure India.https://www.icrisat.org/machine-harvestable-chickpea-varieties-for-a-self-sufficient-food-and-nutrition-secure-india/
○
Kanouni H, Farayedi Y, Sabaghpour S, Sadeghzadeh-Ahari D, Shahab M, Kamel M, 2014. Saral, new chickpea variety to expand autumn sowing in highland cold areas of Iran. Res Achiev Field Hort Crops 2 (4): 265-276.
○
MacDon Industries Ltd., 2019. D65 draper headers for combine.https://www.macdon.com/en/products/d65-draper-headers-for-combine/
○
Managing and Planning Institute, 2016. Yearly statistics of Kurdistan province: Agriculture, Forestry, and Fisheries. The Managing and Planning Institute, Planning and Budget Organization, Government Department, Iran.https://kurdistan.mporg.ir/Portal/View/Page.aspx?PageId=77ca1d0b-79ec-4f3c-b424-32925714d0ce&t=13[In Farsi].
○
McVay KA, 2019. Chickpea production. Montana State University Extension MontGuides.https://aes-swcrc.agsci.colostate.edu/wp-content/uploads/sites/92/2019/03/MSU-Extension-Chickpea-Production.pdf
○
Miller M, Wright M, Mailander M, Beard J, 1990. A two-link harvester reel. Appl Eng Agr 6 (2): 131-137.https://doi.org/10.13031/2013.26359
○
Modares Motlagh A, Rostampour V, Mardani K, 2018. Design, fabrication and evaluation of a short-legged chickpea harvest machine. Iran J Biosyst Eng 49 (1): 83-94.
○
Muehlbauer FJ, Sarker A, 2017. Economic importance of chickpea: production, value, and world trade. In: The chickpea genome. Springer Int Publ AG.https://doi.org/10.1007/978-3-319-66117-9_2
○
Oduori MF, Mbuya TO, Sakai J, Inoue E, 2008. Shattered rice grain loss attributable to the combine harvester reel: Model formulation and fitting to field data. Agr Eng Int: CIGR J X, PM 06 013.
○
Oduori MF, Mbuya TO, Sakai J, Inoue E, 2012a. Modeling of crop stem deflection in the context of combine harvester reel design and operation. Agr Eng Int: CIGR J 14 (2): 21-28.
○
Oduori MF, Mbuya TO, Sakai J, Inoue E, 2012b. Kinematics of the tined combine harvester reel. Agr Eng Int: CIGR J 14 (3): 53-60.
○
Paulsen MR, Pinto FA, de Sena Jr DG, Zandonadi RS, Ruffato S, Costa AG, Ragagnin VA, Danao MGC, 2014. Measurement of combine losses for corn and soybeans in Brazil. Appl Eng Agr 30 (6): 841-855.https://doi.org/10.13031/aea.30.10360
○
Paulsen MR, Kalita PK, Rausch KD, 2015. Postharvest losses due to harvesting operations in developing countries: a review. 2015 ASABE Annual International Meeting.
Quick GR, 1972. Analysis of the combine header and design for the reduction of gathering loss in soybeans.Iowa State University, Ph.D. Dissertation.
○
Saiz-Rubio V, Rovira-Más F, 2020. From smart farming towards agriculture 5.0: A review on crop data management. Agronomy 10 (207).https://doi.org/10.3390/agronomy10020207
○
Sakai J, Inoue E, Oduori MF, 1993. Combine harvester reel stagger-I. principle of determination of reel stagger based on reel kinematics and crop stem deflection. Ama-Agr Mech Asia AF 24: 27-27.
○
Saskatchewan Pulse Growers, 2020. Pulse knowledge herbicides for pre-harvest use in pulses.https://saskpulse.com/files/newsletters/200713_Pre_Harvest_Options_for_Pulses_2020.pdf
○
Shahbazi F, 2018. Effects of moisture content and level in the crop on the shearing properties of chickpea stem. Agr Eng Int: CIGR J 19 (4): 187-192.
○
Sidahmed M, Jaber N, 2004. The design and testing of a cutter and feeder mechanism for the mechanical harvesting of lentils. Biosyst Eng 88 (3): 295-304.https://doi.org/10.1016/j.biosystemseng.2004.04.002
○
Siemens MC, 2006. Effect of guard spacing, guard attachments and reel type on chickpea harvesting losses. Appl Eng Agr 22 (5): 651-657.https://doi.org/10.13031/2013.21997
○
Singh U, Gaur P, Singh G, Chaturvedi S, 2018. Mechanical harvesting of chickpea: Agronomic interventions. In: Farm mechanization for production. Scientific Publisher, India.
○
The Atlantic, 2019. In the future, everything will be made of chickpeas.https://www.theatlantic.com/health/archive/2019/03/chickpea-products-have-exploded-popularity-us/584956/
○
UCDavice, 2014. Feed the future. The United States Global Government Hunger and Food Security Institute.http://chickpealab.ucdavis.edu/
○
Yavari I, 2017. A new platform equipped with a pneumatic feeder for harvesting chickpeas and lentils.http://www.iana.ir[In Frasi].
○
Zobeiri M, Rostampour V, Rezvanivand Fanaei A, Nikbakht AM, 2020. Experimental and numerical investigation of deviation blade effect on sedimentation chamber performance in chickpea harvesting machine. Iran J Biosyst Eng 51 (2): 329-339. [In Farsi].