- Email: [email protected]
PM—Power and Machinery
J. agric. Engng Res., 2000, 77 (3), 297}301 doi:10.1006/jaer.2000.0600, available online at http://www.idealibrary.com on PM*Power and Machinery
Soya Bean Threshing by Nylon Cords on Rotating Shafts C. Mesquita; M. Hanna; N. Costa; J. Franc,a Neto EMBRAPA, Londrina, PR, Brasil Department of Biological Systems Engineering, University of Nebraska, 211 Chase Hall, Lincoln, NE 68583-0726, USA; e-mail corresponding author: [email protected] (Received 1 October 1999; accepted in revised form 29 June 2000; published online 29 August 2000)
An experimental device was built for threshing standing, uncut soya bean plants. It used impact energy provided by nylon cords, "xed on counter-rotating shafts, striking the soya beans from both sides of the plant row. The device threshed up to 99% of the beans depending on the ground speed. The material-other-than-grain removed at slower speeds was signi"cantly more than that removed at faster ground speeds. Ground speed had no e!ect on seed vigour. However, the vigour of seeds harvested with the experimental device was signi"cantly higher compared to those harvested conventionally. The estimated average energy required by the threshing device was 4 MJ/ha. 2000 Silsoe Research Institute
1. Introduction Combine harvester studies involving the harvest of soya beans have been concerned predominately with the improvement of components to reduce the amount of grain loss and to increase harvesting capacity, rather than with any major changes in the combine harvester's functional characteristics which would simplify the overall design and reduce operating costs. Consequently, the growing demand for soya beans has contributed to an increase in machine size, energy consumption, and operational expenditures, making harvesting one of the highest input costs required for producing soya beans. Many combine harvesters still retain all of the functional characteristics originally designed for the harvest of cereal grains, such as the tangentially fed threshing cylinder and concave, patented over 200 years ago. The operational characteristics of existing combine harvesters require that the entire soya bean plant be cut before being threshed, separated and cleaned. New designs introduced in the USA and Europe suggest that a reduction in the processing of material other than grain (MOG) is a major factor contributing to the harvest of higher quality beans, a more e$cient use of energy and a reduction in operation costs. This challenges researchers to design simpler and cheaper harvesters which do not require plants to be cut and processed to collect the seeds. This research follows a sequence of studies carried out to evaluate di!erent ways of imparting impact energy to 0021-8634/00/110297#05 $35.00/0
thresh soya beans from an unharvested crop. Nylon cords on rotating shafts were intended to thresh soya beans from the pods in the "eld. As the overall objective was principally to evaluate the unit's ability to e!ectively remove soya beans from the pods and plants (its threshing e$ciency) the prototype was not fully developed and, therefore, did not include any mechanism for collecting cleaning, and transporting the seeds. The objectives were to: (1) evaluate and compare threshing e$ciencies based on the number of pods shattered and the mass of seeds released; (2) determine the mass of pods detached from the stems; (3) determine the mass of MOG removed by the prototype travelling at four di!erent ground speeds; (4) evaluate and compare mechanical damage of unbroken seeds; (5) determine the amount of seeds broken; (6) determine the vigour of the seeds threshed and (7) estimate the amount of energy required by the prototype to thresh soya beans.
2. Literature review The dehiscent characteristic of soya bean pods directed most of the initial research on soya bean harvesting to improve combine harvester header components to reduce seed losses resulting from pod shattering. Components were modi"ed to reduce the impact on soya bean pods and also to reduce the cutting height. Improvements included #exible headers and automatic height
297
2000 Silsoe Research Institute
298
C . M ES Q U I TA E¹ A¸.
control devises. According to Bichel and Hengen (1977), the state of the art of soya bean harvest technology is the result of more than 90 patents on devices whose purposes were to reduce crop gathering losses. Most combine harvesters still use the conventional transverse cylinder and concave for the threshing mechanism, the original idea having been patented over two centuries ago (Quick, 1977). The axial #ow principle was patented in Germany in 1886 (Atares, 1990). The axial #ow rotary threshing system was introduced on North American combine harvesters approximately 25 years ago. According to Gasparetto et al. (1977), the principal aim of the threshing device is to eliminate grain loss during the threshing process, to reduce both macro- and microscopic damage and to separate the grain. It was recognized that threshing was still far from being at a desirable level of e$ciency. In order to maintain capacity when threshing entire soya bean plants, both transverse threshing cylinders and axial rotors require a considerable amount of energy. Paradoxically, Mesquita (1989) found that only a small amount of energy was necessary to shatter soya bean pods. This contradiction can be explained by the fact that the threshing cylinder has to process the whole plant instead of only the pods. Mesquita and Hanna (1993a, 1993b, 1996) studied the mechanics of threshing soya beans without cutting and processing the plant. An experimental unit was developed to analyse the mechanical actions of frictional rubbing and impact on soya bean plants. A threshing e$ciency of over 93% was obtained with frictional rubbing. Over 92, 95 and 97% threshing e$ciencies were obtained with impact by a moving metal surface, rotating nylon cords and plastic pellets, respectively. To simulate the movement of an experimental unit over a row of soya bean plants in the laboratory, Mesquita et al. (1997) used a commercially available blast wheel to throw plastic pellets laterally against an established crop of soya bean plants. With the blast stream hitting only one side of the plant row, over 92% threshing e$ciency was obtained with 12% moisture, with 5)7% of MOG removed and 0)1% of seeds broken.
3. Materials and methods This study was part of a joint research project carried out at the Biological Systems Engineering Department of the University of Nebraska, Lincoln, Nebraska and the National Centre for Soya Bean Research of Embrapa (Brazilian Agricultural Research Corporation), Londrina, ParanaH State, Brazil. The threshing concept discussed in this paper is covered by a Brazilian patent (protocol no. 009667; Mesquita & Moreira, 1998).
Fig. 1. Conceptual views of the experimental threshing device
ROTA Farm Machinery Industry, CambeH , ParanaH State, Brasil, joined the collaborative e!ort to manufacture this and future prototypes. The prototype evaluated in this study was basically made of nylon cords "xed onto two parallel counter-rotating steel shafts (3)1 cm diameter, 1)5 m length) driven by a tractor power take-o! and assembled on a frame connected to the three-point hitch of the tractor as shown in Fig. 1. The shafts were set 10 cm apart and at 303 to the horizontal, inclining upwards from the back towards the front part of the prototype. Nylon cords, measuring 10 cm each and set 1 cm apart, were radially and symmetrically "xed into diametral holes drilled in a spiral path on the shafts. The shafts rotated at 2600 min\ creating an upward sweeping motion at both sides of the plant row, with the cords shattering the pods. Row dividers were used to lift the plants into an upright position before entering between the shafts as shown in Fig. 2. After preliminary tests were
S O Y A BE AN TH R ES H IN G
Fig. 2. Experimental device during xeld threshing tests
conducted to determine any adjustments that might be required, a collecting chamber, made of metal and rubber sheets and a collecting pan, were improvised to collect the seed samples and MOG for further analyses as shown in Fig. 2. A Massey Ferguson model MF 265 tractor was used to drive the prototype at 2)2, 3)2, 6)0, and 7)2 km/h, which corresponded to the four low gear ground speeds of that tractor model. An SLC-John Deere model 7500 conventional combine harvester was used to harvest a randomly selected part of the "eld at 4 km/h with the threshing cylinder adjusted to 600 min\. Four seed samples, weighing approximately 2 kg each, were taken from the grain reservoir of the combine harvester as a control to enable comparisons between seed breakage and seed vigour. The test was carried out in a 150 m long, 30 m wide soya bean "eld plot, when the moisture content of the soya bean cultivar Embrapa 48 averaged approximately 12%. Moisture content was measured with a portable meter (Moisture Chek model 16060 manufactured by Deere and Co.). A randomized complete block design was used to compare the threshing e$ciency, number of pods detached and the amount of MOG removed data obtained from ten replicated samples for each of four di!erent ground speeds. Another randomized complete block design compared the mean percentages of mechanically damaged unbroken seeds, broken seeds and seed vigour, determined from four replicated samples. These samples were obtained from the threshing device for each of the four ground speeds, by hand threshing and from conventionally combined control plots. Two separate rows of plants were randomly selected for the sampling. The samples were taken from a metre of each row. Threshing e$ciency was recorded as the ratio of the mean of the unthreshed pods/plant, following threshing,
299
to the mean of the total pods/plant obtained from 142 randomly selected plants. It also was recorded as the ratio of the mean mass of unthreshed seeds/plant, following threshing, to the mean mass of total seeds/plant obtained from 142 randomly selected plants. The fraction of pods detached was determined as the ratio of the mean mass of pods and pod fragments remaining attached to the stem, following threshing, to the mean mass of all empty pods/plant obtained from 142 randomly selected plants. MOG was expressed as the ratio of non-seed plant material, including pods and stems, removed during threshing to the total above-ground non-seed plant mass. A sample of 142 randomly selected plants was used in the evaluation. Mechanically damaged but unbroken seeds were identi"ed using the tetrazolium test as described by Franc,a Neto et al. (1988) and the hypochlorite test as described by Vaughan (1982). The fraction of broken seeds was the ratio of the mean mass of broken seeds to the mean mass of total seeds in a sample. Seed vigour also was determined using the tetrazolium test. The torque and power required to rotate the shafts were measured with a torque meter, attached to the power take-o! shaft to estimate the energy required to harvest 1 h of soya beans. Standard deviations (SDs), 95% con"dence intervals and coe$cients of variation were calculated to express more clearly the reliability of the results for threshing e$ciency, pods detached and MOG removed.
4. Results and discussion The mean seed threshing e$ciencies (ratio of mass of seeds threshed to the total mass of seeds on a plant or plants) and the amount of pods detached from stems at 6 and 7)2 km/h were signi"cantly lower than at 2)2 and 3)2 km/h as shown in Table 1. Nevertheless, even the lowest mean for threshing e$ciency, obtained at 6 km/h, was found to be satisfactory when compared to the nearly 5% harvesting losses averaged by conventional combine harvesters in Brazil (Costa et al., 1997a). Table 1 shows the signi"cant di!erence of approximately 24% between pods detached from stems at 6 and 7)2 km/h and pods detached at 2)2 and 3)2 km/h, showing an important advantage of harvesting at higher ground speeds, provided satisfactory threshing e$ciency is maintained. The overall mean of MOG removed, at 29%, was much less than with a conventional combine harvester where almost 100% of the plant (excluding the roots) is removed and processed. There were no signi"cant di!erences among the mean percentages of damaged but unbroken seeds threshed by the device and those threshed by hand, as shown in
300
C . M ES Q U I TA E¹ A¸.
Table 1 Seed threshing e7ciency, pods detached and material other than grain (MOG) removed at di4erent ground speeds = 1997* Threshing ezciency, % Ground speed, km/h 2)2 3)2 6)0 7)2 All speeds SD Mean 95% C.I.S CVA, %
Opened pods
Mass of seeds
Pods detached, %
MOG removed, %
98)7 R 98)7 95)4 96)3
99)0 98)9 94)8 960
88)5 86)7 63)8 62)4
33)1 31)1 26)2 25)4
2)00 97)3 96)7)l)97)9 1)5
2)32 97)2 96)5)l)97)9 1)5
13)5 75)4 71)0)l)79)7 8)2
11)5 29)0 25)3)l)32)6 32)6
*Sample size per ground speed was 210 plants. RMeans followed by the same letter within columns are not di!erent at the 5% level (Duncan test). SDenotes con"dence interval. ADenotes coe$cient of variation.
Table 2. However, all treatments resulted in signi"cantly less damage compared to the conventional combine harvester treatment. The experimental device produced a statistically lower level of broken seeds than the conventional combine harvester. The overall mean of seeds broken, approximately 0)4%, by the experimental device also was considerably better than the 8% reported by Costa et al. (1997b) in a survey carried out in ParanaH , Santa Catarina and Mato Grosso States in Brazil. The vigour of the hand threshed seeds was not statistically di!erent from the vigour of the seeds threshed by the experimental device at 6 and 7)2 km/h as shown in Table 2. However, the vigour of the hand threshed seeds was signi"cantly higher compared to the vigour of the seeds threshed by the experimental device at 2)2 and
3)2 km/h and to those threshed by the conventional combine harvester, which had the lowest mean. The torque demanded by both shafts was 3)5 Nm and the estimated energy required by the device to thresh 1 h of soya beans was 6)7, 4)7, 2)4 and 2 MJ/ha at ground speeds of 2)2, 3)2, 6 and 7)2 km/h, respectively. According to Deere and Company (1981), the average total energy required for combine harvesting soya beans was 80 MJ/ha. Combining that with estimates by Kanafojski and Karwowski (1976) and Hursman (1983) which indicated that threshing mechanisms used 40% of the total energy, the estimated energy used by conventional combine harvesters to thresh soya beans is approximately 32 MJ/ha. Comparatively, the estimated energies used by the experimental device were 5}16 times lower. This
Table 2 Mechanically damaged but unbroken seeds, seed breakage and seed vigour resulting from threshing soya beans with the nylon cords, by hand and by conventional combine harvester = 1997 Mechanical damage, % TZ (6}8)* 1)00 bR
Hypochlorite 8)5b
Seeds broken, % 0)00 c
Seed vigour, % 78)5a
Threshing with nylon cords Ground speed, km/h 2)2 3)2 6)0 7)2
2)25 3)50 1)75 1)75
11)4 12)7 10)0 9)5
0)52 0)56 0)31 0)37
67)2 67)0 78)5 74)0
Conventional combine
6)25
24)3
8)38
63)5
Treatments Hand threshed
*Tetrazolium (TZ) test, percentage of seeds not expected to germinate. RMeans followed by the same letter within columns are not di!erent at the 5% level (Duncan test).
S O Y A BE AN TH R ES H IN G
energy also was 2}7 times higher than the impact energy of 1 MJ/ha estimated to be required to shatter the soya bean pods (Mesquita & Hanna, 1993b). The overall results showed encouraging performance of the nylon cords. Satisfactory threshing performance associated with the low levels of MOG removed and seeds broken, suggests that the impact from nylon cords, which provided enough energy to thresh/open the pods would allow the harvest of soya beans without the need for cutting or processing of the plants.
5. Conclusions An experimental device, involving the use of nylon cords on rotating shafts, was constructed to thresh soya beans by striking the pods on an unharvested crop of plants. The principle of this concept was to impart energy on the pods causing them to shatter. From the results, the following conclusions were drawn: (1) seed threshing e$ciencies between 94)8 and 99% were encouraging; (2) the amount of mechanically damaged but unbroken seeds obtained by threshing with nylon cords was substantially lower than for threshing with a conventional combine harvester; (3) levels of seeds broken of between 0)6 and 0)3% obtained with the experimental threshing device were considerably lower than the 8)4% level experienced with the conventional combine harvester; (4) seed vigour resulting from threshing with the experimental device travelling at 6 and 7)2 km/h did not di!er from the vigour of hand-threshed seeds, and (5) the energy required to thresh soya beans with the experimental device was considerably less than the reported estimated energy used by the conventional combine harvesters to thresh soya beans.
References Atares P A (1990). Novedades en la recoleccioH n de cereales [News on grain harvesting]. Maquinas Y Tractores, 5, 24}35 Bichel D C; Hengen E J (1977). Development of soybean harvesting equipment in the USA. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 200}208. ASAE, St Joseph, MI Costa N P; Mesquita C M; Maurina A; Andrade J G M (1997a). Reduc,a o de perdas na colheita da soja: Tecnologia ao alcance de teH cnicos e produtores. [Losses reduction in
301
soybean harvesting: technology for technicians and growers]. Embrapa Sede, BrasmH lia, DF. Cadernos de Cie( ncia and Tecnologia, 14(3), 465}472 Costa N P; Mesquita C M; Franc,a Neto J B; Krzyzanowski F C; Henning A A; Mandarino J M G; Pereira J E (1997b). Avaliac,a o da qualidade de sementes e de gra os de soja, produzidos nos estados do ParanaH , Santa Catarina e Mato Grosso, na safra 96/97. [Evaluation of soybean seeds and grain quality produced in Parana, Santa Catarina, and Mato Grosso States during 1996/97 crop]. ABRATES, BrasmH lia, DF. Informativo ABRATES, 7(1/2), 86, July/August Deere and Company Machinery Management (1981). Fundamentals of Machine Operation. (2nd Edn.), p. 196. Deere and Company, Moline, IL Franc,a Neto J de B; Pereira L A G; Costa N P; Krzyzanowski F C; Henning A A (1988). Metodologia do teste de tetrazoH lio em sementes de soja [Methodology of the tetrazolium test for soybean seed]. Embrapa, National Center for Soybean Research, Documentos, pp 32}43. Londrina, PR, Brazil Gasparetto E; Zen M; Guadagnin A (1977). Ultra-high speed movie observation of a conventional threshing mechanism (cylinder-concave-rear beater) working on wheat. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 104}111. ASAE, St Joseph, MI Hursman W (1983). Optimum cereal combine harvester operation by means of automatic machine and threshing speed control. PhD Thesis, Wageningen University, Netherlands Kanafojski C; Karwowski T (1976). Agricultural Machines, Theory and Construction. Vol. 2. Foreign Scienti"c Publications Department of the National Center for Scienti"c Technical and Economic Information, Warsaw, Poland. Department of Commerce, National Technical Information Service, Spring"eld, VA, US Mesquita C M (1989). Mechanics of soybean threshing. Ph.D. Thesis, University of Nebraska-Lincoln Mesquita C M; Hanna M A (1993a). Soybean threshing mechanics: I. Frictional rubbing by #at belts. Transactions of the ASAE, 36(2), 275}279 Mesquita C M; Hanna M A (1993b). Soybean threshing mechanics: II. Impact. Transactions of the ASAE, 36(2), 281}284 Mesquita C M; Hanna M A (1996). Soybean threshing devices. Applied Engineering in Agriculture ASAE, 12(1), 15}19 Mesquita C M; Hanna M A; Weber R W (1997). Blast wheel device for threshing soybeans. Transactions of the ASAE, 40(3), 541}546 Mesquita C M; Moreira R C (1998). Improved device for grain harvesting. Patent pending with Brazilian National Institute for Industrial Property Quick G R (1977). Development of rotary and axial thresher/separators. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 151}164, 169. ASAE, St Joseph, MI Vaughan C E (1982). Quality assurance techniques: the chlorox test (soybeans). Proceedings 1982 Short Course for Seedsmen, pp 117}118, MS
Soya Bean Threshing by Nylon Cords on Rotating Shafts C. Mesquita; M. Hanna; N. Costa; J. Franc,a Neto EMBRAPA, Londrina, PR, Brasil Department of Biological Systems Engineering, University of Nebraska, 211 Chase Hall, Lincoln, NE 68583-0726, USA; e-mail corresponding author: [email protected] (Received 1 October 1999; accepted in revised form 29 June 2000; published online 29 August 2000)
An experimental device was built for threshing standing, uncut soya bean plants. It used impact energy provided by nylon cords, "xed on counter-rotating shafts, striking the soya beans from both sides of the plant row. The device threshed up to 99% of the beans depending on the ground speed. The material-other-than-grain removed at slower speeds was signi"cantly more than that removed at faster ground speeds. Ground speed had no e!ect on seed vigour. However, the vigour of seeds harvested with the experimental device was signi"cantly higher compared to those harvested conventionally. The estimated average energy required by the threshing device was 4 MJ/ha. 2000 Silsoe Research Institute
1. Introduction Combine harvester studies involving the harvest of soya beans have been concerned predominately with the improvement of components to reduce the amount of grain loss and to increase harvesting capacity, rather than with any major changes in the combine harvester's functional characteristics which would simplify the overall design and reduce operating costs. Consequently, the growing demand for soya beans has contributed to an increase in machine size, energy consumption, and operational expenditures, making harvesting one of the highest input costs required for producing soya beans. Many combine harvesters still retain all of the functional characteristics originally designed for the harvest of cereal grains, such as the tangentially fed threshing cylinder and concave, patented over 200 years ago. The operational characteristics of existing combine harvesters require that the entire soya bean plant be cut before being threshed, separated and cleaned. New designs introduced in the USA and Europe suggest that a reduction in the processing of material other than grain (MOG) is a major factor contributing to the harvest of higher quality beans, a more e$cient use of energy and a reduction in operation costs. This challenges researchers to design simpler and cheaper harvesters which do not require plants to be cut and processed to collect the seeds. This research follows a sequence of studies carried out to evaluate di!erent ways of imparting impact energy to 0021-8634/00/110297#05 $35.00/0
thresh soya beans from an unharvested crop. Nylon cords on rotating shafts were intended to thresh soya beans from the pods in the "eld. As the overall objective was principally to evaluate the unit's ability to e!ectively remove soya beans from the pods and plants (its threshing e$ciency) the prototype was not fully developed and, therefore, did not include any mechanism for collecting cleaning, and transporting the seeds. The objectives were to: (1) evaluate and compare threshing e$ciencies based on the number of pods shattered and the mass of seeds released; (2) determine the mass of pods detached from the stems; (3) determine the mass of MOG removed by the prototype travelling at four di!erent ground speeds; (4) evaluate and compare mechanical damage of unbroken seeds; (5) determine the amount of seeds broken; (6) determine the vigour of the seeds threshed and (7) estimate the amount of energy required by the prototype to thresh soya beans.
2. Literature review The dehiscent characteristic of soya bean pods directed most of the initial research on soya bean harvesting to improve combine harvester header components to reduce seed losses resulting from pod shattering. Components were modi"ed to reduce the impact on soya bean pods and also to reduce the cutting height. Improvements included #exible headers and automatic height
297
2000 Silsoe Research Institute
298
C . M ES Q U I TA E¹ A¸.
control devises. According to Bichel and Hengen (1977), the state of the art of soya bean harvest technology is the result of more than 90 patents on devices whose purposes were to reduce crop gathering losses. Most combine harvesters still use the conventional transverse cylinder and concave for the threshing mechanism, the original idea having been patented over two centuries ago (Quick, 1977). The axial #ow principle was patented in Germany in 1886 (Atares, 1990). The axial #ow rotary threshing system was introduced on North American combine harvesters approximately 25 years ago. According to Gasparetto et al. (1977), the principal aim of the threshing device is to eliminate grain loss during the threshing process, to reduce both macro- and microscopic damage and to separate the grain. It was recognized that threshing was still far from being at a desirable level of e$ciency. In order to maintain capacity when threshing entire soya bean plants, both transverse threshing cylinders and axial rotors require a considerable amount of energy. Paradoxically, Mesquita (1989) found that only a small amount of energy was necessary to shatter soya bean pods. This contradiction can be explained by the fact that the threshing cylinder has to process the whole plant instead of only the pods. Mesquita and Hanna (1993a, 1993b, 1996) studied the mechanics of threshing soya beans without cutting and processing the plant. An experimental unit was developed to analyse the mechanical actions of frictional rubbing and impact on soya bean plants. A threshing e$ciency of over 93% was obtained with frictional rubbing. Over 92, 95 and 97% threshing e$ciencies were obtained with impact by a moving metal surface, rotating nylon cords and plastic pellets, respectively. To simulate the movement of an experimental unit over a row of soya bean plants in the laboratory, Mesquita et al. (1997) used a commercially available blast wheel to throw plastic pellets laterally against an established crop of soya bean plants. With the blast stream hitting only one side of the plant row, over 92% threshing e$ciency was obtained with 12% moisture, with 5)7% of MOG removed and 0)1% of seeds broken.
3. Materials and methods This study was part of a joint research project carried out at the Biological Systems Engineering Department of the University of Nebraska, Lincoln, Nebraska and the National Centre for Soya Bean Research of Embrapa (Brazilian Agricultural Research Corporation), Londrina, ParanaH State, Brazil. The threshing concept discussed in this paper is covered by a Brazilian patent (protocol no. 009667; Mesquita & Moreira, 1998).
Fig. 1. Conceptual views of the experimental threshing device
ROTA Farm Machinery Industry, CambeH , ParanaH State, Brasil, joined the collaborative e!ort to manufacture this and future prototypes. The prototype evaluated in this study was basically made of nylon cords "xed onto two parallel counter-rotating steel shafts (3)1 cm diameter, 1)5 m length) driven by a tractor power take-o! and assembled on a frame connected to the three-point hitch of the tractor as shown in Fig. 1. The shafts were set 10 cm apart and at 303 to the horizontal, inclining upwards from the back towards the front part of the prototype. Nylon cords, measuring 10 cm each and set 1 cm apart, were radially and symmetrically "xed into diametral holes drilled in a spiral path on the shafts. The shafts rotated at 2600 min\ creating an upward sweeping motion at both sides of the plant row, with the cords shattering the pods. Row dividers were used to lift the plants into an upright position before entering between the shafts as shown in Fig. 2. After preliminary tests were
S O Y A BE AN TH R ES H IN G
Fig. 2. Experimental device during xeld threshing tests
conducted to determine any adjustments that might be required, a collecting chamber, made of metal and rubber sheets and a collecting pan, were improvised to collect the seed samples and MOG for further analyses as shown in Fig. 2. A Massey Ferguson model MF 265 tractor was used to drive the prototype at 2)2, 3)2, 6)0, and 7)2 km/h, which corresponded to the four low gear ground speeds of that tractor model. An SLC-John Deere model 7500 conventional combine harvester was used to harvest a randomly selected part of the "eld at 4 km/h with the threshing cylinder adjusted to 600 min\. Four seed samples, weighing approximately 2 kg each, were taken from the grain reservoir of the combine harvester as a control to enable comparisons between seed breakage and seed vigour. The test was carried out in a 150 m long, 30 m wide soya bean "eld plot, when the moisture content of the soya bean cultivar Embrapa 48 averaged approximately 12%. Moisture content was measured with a portable meter (Moisture Chek model 16060 manufactured by Deere and Co.). A randomized complete block design was used to compare the threshing e$ciency, number of pods detached and the amount of MOG removed data obtained from ten replicated samples for each of four di!erent ground speeds. Another randomized complete block design compared the mean percentages of mechanically damaged unbroken seeds, broken seeds and seed vigour, determined from four replicated samples. These samples were obtained from the threshing device for each of the four ground speeds, by hand threshing and from conventionally combined control plots. Two separate rows of plants were randomly selected for the sampling. The samples were taken from a metre of each row. Threshing e$ciency was recorded as the ratio of the mean of the unthreshed pods/plant, following threshing,
299
to the mean of the total pods/plant obtained from 142 randomly selected plants. It also was recorded as the ratio of the mean mass of unthreshed seeds/plant, following threshing, to the mean mass of total seeds/plant obtained from 142 randomly selected plants. The fraction of pods detached was determined as the ratio of the mean mass of pods and pod fragments remaining attached to the stem, following threshing, to the mean mass of all empty pods/plant obtained from 142 randomly selected plants. MOG was expressed as the ratio of non-seed plant material, including pods and stems, removed during threshing to the total above-ground non-seed plant mass. A sample of 142 randomly selected plants was used in the evaluation. Mechanically damaged but unbroken seeds were identi"ed using the tetrazolium test as described by Franc,a Neto et al. (1988) and the hypochlorite test as described by Vaughan (1982). The fraction of broken seeds was the ratio of the mean mass of broken seeds to the mean mass of total seeds in a sample. Seed vigour also was determined using the tetrazolium test. The torque and power required to rotate the shafts were measured with a torque meter, attached to the power take-o! shaft to estimate the energy required to harvest 1 h of soya beans. Standard deviations (SDs), 95% con"dence intervals and coe$cients of variation were calculated to express more clearly the reliability of the results for threshing e$ciency, pods detached and MOG removed.
4. Results and discussion The mean seed threshing e$ciencies (ratio of mass of seeds threshed to the total mass of seeds on a plant or plants) and the amount of pods detached from stems at 6 and 7)2 km/h were signi"cantly lower than at 2)2 and 3)2 km/h as shown in Table 1. Nevertheless, even the lowest mean for threshing e$ciency, obtained at 6 km/h, was found to be satisfactory when compared to the nearly 5% harvesting losses averaged by conventional combine harvesters in Brazil (Costa et al., 1997a). Table 1 shows the signi"cant di!erence of approximately 24% between pods detached from stems at 6 and 7)2 km/h and pods detached at 2)2 and 3)2 km/h, showing an important advantage of harvesting at higher ground speeds, provided satisfactory threshing e$ciency is maintained. The overall mean of MOG removed, at 29%, was much less than with a conventional combine harvester where almost 100% of the plant (excluding the roots) is removed and processed. There were no signi"cant di!erences among the mean percentages of damaged but unbroken seeds threshed by the device and those threshed by hand, as shown in
300
C . M ES Q U I TA E¹ A¸.
Table 1 Seed threshing e7ciency, pods detached and material other than grain (MOG) removed at di4erent ground speeds = 1997* Threshing ezciency, % Ground speed, km/h 2)2 3)2 6)0 7)2 All speeds SD Mean 95% C.I.S CVA, %
Opened pods
Mass of seeds
Pods detached, %
MOG removed, %
98)7 R 98)7 95)4 96)3
99)0 98)9 94)8 960
88)5 86)7 63)8 62)4
33)1 31)1 26)2 25)4
2)00 97)3 96)7)l)97)9 1)5
2)32 97)2 96)5)l)97)9 1)5
13)5 75)4 71)0)l)79)7 8)2
11)5 29)0 25)3)l)32)6 32)6
*Sample size per ground speed was 210 plants. RMeans followed by the same letter within columns are not di!erent at the 5% level (Duncan test). SDenotes con"dence interval. ADenotes coe$cient of variation.
Table 2. However, all treatments resulted in signi"cantly less damage compared to the conventional combine harvester treatment. The experimental device produced a statistically lower level of broken seeds than the conventional combine harvester. The overall mean of seeds broken, approximately 0)4%, by the experimental device also was considerably better than the 8% reported by Costa et al. (1997b) in a survey carried out in ParanaH , Santa Catarina and Mato Grosso States in Brazil. The vigour of the hand threshed seeds was not statistically di!erent from the vigour of the seeds threshed by the experimental device at 6 and 7)2 km/h as shown in Table 2. However, the vigour of the hand threshed seeds was signi"cantly higher compared to the vigour of the seeds threshed by the experimental device at 2)2 and
3)2 km/h and to those threshed by the conventional combine harvester, which had the lowest mean. The torque demanded by both shafts was 3)5 Nm and the estimated energy required by the device to thresh 1 h of soya beans was 6)7, 4)7, 2)4 and 2 MJ/ha at ground speeds of 2)2, 3)2, 6 and 7)2 km/h, respectively. According to Deere and Company (1981), the average total energy required for combine harvesting soya beans was 80 MJ/ha. Combining that with estimates by Kanafojski and Karwowski (1976) and Hursman (1983) which indicated that threshing mechanisms used 40% of the total energy, the estimated energy used by conventional combine harvesters to thresh soya beans is approximately 32 MJ/ha. Comparatively, the estimated energies used by the experimental device were 5}16 times lower. This
Table 2 Mechanically damaged but unbroken seeds, seed breakage and seed vigour resulting from threshing soya beans with the nylon cords, by hand and by conventional combine harvester = 1997 Mechanical damage, % TZ (6}8)* 1)00 bR
Hypochlorite 8)5b
Seeds broken, % 0)00 c
Seed vigour, % 78)5a
Threshing with nylon cords Ground speed, km/h 2)2 3)2 6)0 7)2
2)25 3)50 1)75 1)75
11)4 12)7 10)0 9)5
0)52 0)56 0)31 0)37
67)2 67)0 78)5 74)0
Conventional combine
6)25
24)3
8)38
63)5
Treatments Hand threshed
*Tetrazolium (TZ) test, percentage of seeds not expected to germinate. RMeans followed by the same letter within columns are not di!erent at the 5% level (Duncan test).
S O Y A BE AN TH R ES H IN G
energy also was 2}7 times higher than the impact energy of 1 MJ/ha estimated to be required to shatter the soya bean pods (Mesquita & Hanna, 1993b). The overall results showed encouraging performance of the nylon cords. Satisfactory threshing performance associated with the low levels of MOG removed and seeds broken, suggests that the impact from nylon cords, which provided enough energy to thresh/open the pods would allow the harvest of soya beans without the need for cutting or processing of the plants.
5. Conclusions An experimental device, involving the use of nylon cords on rotating shafts, was constructed to thresh soya beans by striking the pods on an unharvested crop of plants. The principle of this concept was to impart energy on the pods causing them to shatter. From the results, the following conclusions were drawn: (1) seed threshing e$ciencies between 94)8 and 99% were encouraging; (2) the amount of mechanically damaged but unbroken seeds obtained by threshing with nylon cords was substantially lower than for threshing with a conventional combine harvester; (3) levels of seeds broken of between 0)6 and 0)3% obtained with the experimental threshing device were considerably lower than the 8)4% level experienced with the conventional combine harvester; (4) seed vigour resulting from threshing with the experimental device travelling at 6 and 7)2 km/h did not di!er from the vigour of hand-threshed seeds, and (5) the energy required to thresh soya beans with the experimental device was considerably less than the reported estimated energy used by the conventional combine harvesters to thresh soya beans.
References Atares P A (1990). Novedades en la recoleccioH n de cereales [News on grain harvesting]. Maquinas Y Tractores, 5, 24}35 Bichel D C; Hengen E J (1977). Development of soybean harvesting equipment in the USA. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 200}208. ASAE, St Joseph, MI Costa N P; Mesquita C M; Maurina A; Andrade J G M (1997a). Reduc,a o de perdas na colheita da soja: Tecnologia ao alcance de teH cnicos e produtores. [Losses reduction in
301
soybean harvesting: technology for technicians and growers]. Embrapa Sede, BrasmH lia, DF. Cadernos de Cie( ncia and Tecnologia, 14(3), 465}472 Costa N P; Mesquita C M; Franc,a Neto J B; Krzyzanowski F C; Henning A A; Mandarino J M G; Pereira J E (1997b). Avaliac,a o da qualidade de sementes e de gra os de soja, produzidos nos estados do ParanaH , Santa Catarina e Mato Grosso, na safra 96/97. [Evaluation of soybean seeds and grain quality produced in Parana, Santa Catarina, and Mato Grosso States during 1996/97 crop]. ABRATES, BrasmH lia, DF. Informativo ABRATES, 7(1/2), 86, July/August Deere and Company Machinery Management (1981). Fundamentals of Machine Operation. (2nd Edn.), p. 196. Deere and Company, Moline, IL Franc,a Neto J de B; Pereira L A G; Costa N P; Krzyzanowski F C; Henning A A (1988). Metodologia do teste de tetrazoH lio em sementes de soja [Methodology of the tetrazolium test for soybean seed]. Embrapa, National Center for Soybean Research, Documentos, pp 32}43. Londrina, PR, Brazil Gasparetto E; Zen M; Guadagnin A (1977). Ultra-high speed movie observation of a conventional threshing mechanism (cylinder-concave-rear beater) working on wheat. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 104}111. ASAE, St Joseph, MI Hursman W (1983). Optimum cereal combine harvester operation by means of automatic machine and threshing speed control. PhD Thesis, Wageningen University, Netherlands Kanafojski C; Karwowski T (1976). Agricultural Machines, Theory and Construction. Vol. 2. Foreign Scienti"c Publications Department of the National Center for Scienti"c Technical and Economic Information, Warsaw, Poland. Department of Commerce, National Technical Information Service, Spring"eld, VA, US Mesquita C M (1989). Mechanics of soybean threshing. Ph.D. Thesis, University of Nebraska-Lincoln Mesquita C M; Hanna M A (1993a). Soybean threshing mechanics: I. Frictional rubbing by #at belts. Transactions of the ASAE, 36(2), 275}279 Mesquita C M; Hanna M A (1993b). Soybean threshing mechanics: II. Impact. Transactions of the ASAE, 36(2), 281}284 Mesquita C M; Hanna M A (1996). Soybean threshing devices. Applied Engineering in Agriculture ASAE, 12(1), 15}19 Mesquita C M; Hanna M A; Weber R W (1997). Blast wheel device for threshing soybeans. Transactions of the ASAE, 40(3), 541}546 Mesquita C M; Moreira R C (1998). Improved device for grain harvesting. Patent pending with Brazilian National Institute for Industrial Property Quick G R (1977). Development of rotary and axial thresher/separators. In: Proceedings of the First International Grain and Forage Harvesting Conference, pp 151}164, 169. ASAE, St Joseph, MI Vaughan C E (1982). Quality assurance techniques: the chlorox test (soybeans). Proceedings 1982 Short Course for Seedsmen, pp 117}118, MS