Ergonomic Evaluation of Manually Operated Six-Row Paddy Transplanter


Master's Thesis, 2005

60 Pages


Excerpt

CONTENTS

CHAPTER PARTICULARS

ABSTRACT

ACKNOWLEDGEMENT

CONTENTS

LIST OF TABLES

LIST OF FIGURES

NOMENCLATURE

I INTRODUCTION

II REVIEW OF LITERATURE
2.1 Physiological Evaluation
2.2 Rest Pause
2.3 Energy Requirement
2.4 Force Measurement

III MATERIALS AND METHODS
3.1 Selection of Subjects for the Transplanting Operation
3.2 Growing of Seedlings
3.3 Preparation of the Field for Transplanting
3.4 Transplanting of Seedlings
3.5 Manually Operated Six-row Paddy Transplanter
3.6 Ergonomic Evaluation
3.6.1 Heart rate measurement
3.6.2 Energy cost of operation
3.6.3 Rest during work
3.6.4 Force measurement in paddy transplanting operation

IV RESULTS AND DISCUSSION
4.1 Selection of Subjects
4.2 Paddy Transplanter
4.3 Physiological Aspects of the Subjects
4.3.1 Heart rate variation
4.3.2 Energy expenditure rate
4.3.3 Rest pause
4.3.4 Transplanting force

V SUMMARY AND CONCLUSIONS

BIBLIOGRAPHY

Appendix

ABSTRACT

Ergonomic evaluation of manually operated six-row paddy transplanter was carried out. Human energy is predominantly used in most of the rice farming operations starting from seedbed preparation to threshing. High labour demand during the peak periods adversely affects the timeliness of operation, thereby reducing the crop yield. To offset these problems, mechanical transplanting is the solution. For that farm implements and machinery have been ergonomically designed which minimize drudgery of the labour and increase productivity at reduced expenditure levels which can provide a rational basis for recommendation of methods and improvement in equipment design for more output and operator’s comfort and safety. Three male and female subjects were selected randomly. The parameters used for the study include heart rate and force measurement to get energy cost and rest pause.

The physiological cost was worked out during transplanting operation by manually operated six-row paddy transplanter for male and female subjects, which was found to be 30.70 and 32.58 kJ min-1 respectively. On the basis of the heart rate, the operation by manually operated transplanter was graded as ‘heavy’. Similarly transplanting by hand, the physiological cost was found to be 22.46 and 20.45 kJ min-1 for male and female subjects respectively and accordingly graded as ‘moderately heavy’.

The rest pause for achieving functional effectiveness of the paddy transplanter is 30 minutes of work followed by 14.30 min rest. More force in pulling the transplanter in forward direction by male and female subjects was obtained which was 130.32 and 145.12 N respectively as compare to force required in handle up and handle down position of the transplanter which were 101.93 and 94.61 N for male subject while for female subject, it was 117.08 and 109.34 N respectively. More force is required for female workers as compared to male workers because of males are stronger in pulling the transplanter.

KEY WORDS: Paddy transplanter, Heart rate, Rest pause, Transplanting

ACKNOWLEDGEMENT

It is indeed great pleasure for me and privilege too, in having an opportunity to express my whole hearted sense of gratitude to Dr. Rajvir Yadav, Professor, Deptt. of Farm Machinery and Power, College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh, for his keen interest, talented and valuable guidance, creative suggestions, useful criticism, untiring and ever willing help during the entire prosecution of the study.

It is my pleasant duty to express the heartfelt gratitude and regards to Dr. R. Subbaiah, Professor & Head, Deptt. of SWE, Dr. A. H. Raval, Prof. & Head, Deptt. of AEEE, Prof. N. K. Mistry, Assistant Professor (SG), Deptt. of RE & RE, CAET, JAU, Junagadh, Prof. S. P. Shukla, Associate Professor, Deptt. of Soil and Water Engineering, N. M. College of Agriculture, N.A.U., Navsari, the members of advisory committee, for their directives and helpful guidance throughout the course of research work.

It is my proud privilege to thank Dr. N. C. Patel, Principal & Dean, CAET, JAU, Junagadh, for providing necessary facilities during the course of investigation. Thanks to Prof. J. B. Savani, Professor and Head, Deptt. of Farm Machinery and Power, for providing all the help and facilities to carry out this work.

I wish to place on record my special thanks to Dr. M. Mallik, Director of Research and Dean (PG Studies), Navsari Agricultural University, Navsari and Head, Deptt. of Soil and Water Engineering, Prof. S. P. Shukla, Associate Proffesor, Mr. A. L. Chalodia, Mr. A. M. Mistry, Mr. N. J. Tandel and Balvantbhai, Deptt. of Soil and Water Engineering, N. M. College of Agriculture, Navsari Agricultural University, Navsari, for their continuous encouragement, advice and ever willing help at every stage of work.

I would loss no opportunity to record my sincere thanks to Mr. R. B. Patel, Assistant Research Scientist, Mr. J. M. Patel, Mr. D. K. Dave and other staff members of the Department of Soil and Water Management Research Unit, Navsari Agricultural University, Navsari, for their untiring and kind cooperation to complete this project work.

I will be injustice if I do not express my greatfulness to my seniors Er. S. R. Pund, Er. Sanjaykumar Yadav and Er. G. Prajapati for their guidance and moral support during the course of investigation.I would like to acknowledge the financial assistance provided by the ASPEE Agricultural Research and Development Foundation, Malad (W), Mumbai, by awarding Research Scholarship during the course of investigation.

I will fail in my duties if I do not take this opportunity to record my love, affection, gratitude and reverence to my beloved parents, brother and sister whose encouragement, patience and kind blessing could lead my difficult task to see this day of achievement and satisfaction. I wish to acknowledge my reserved thanks to my friends and colleagues.

Junagadh

(Patel Mitalbahen Bhikhubhai)

LIST OF TABLES

2.1 Grade of physical work based on EER, HR and OCR

2.2 Classification of physical work according to severity of workload

2.3 Subject height Vs handle height from ground at point of minimum force

3.1 Anthropometric dimensions of the subjects

3.2 Seedlings conditions

3.3 Field conditions

3.4 Initial heart rate of the subjects at rest

3.5 Specifications of the transplanter

4.1 Average anthropometric dimensions of the male and female subjects

4.2 Performance data of paddy transplanter in the puddle field during transplanting

4.3 Heart rate of male subject during transplanting operation by manually operated six-row paddy transplanter

4.4 Heart rate of female subject during transplanting operation by manually operated six-row paddy transplanter

4.5 Heart rate of male subject during transplanting operation by hand

4.6 Heart rate of female subject during transplanting operation by hand

4.7 Physiological response of the subjects for transplanting operation by paddy transplanter

4.8 Physiological response of the subjects for transplanting operation by hand

4.9 Calculated rest pause of the subjects for transplanter operation

4.10 Force required to operate paddy transplanter

LIST OF FIGURES

3.1 Ordinary plastic sheet laid on raised bed with wooden frame

3.2 Paste of soil, FYM and sand

3.3 Paste placed over the plastic sheet

3.4 Pregerminated seeds

3.5 Pregerminated seeds placed uniformly over the plastic sheet surface

3.6 Surface press slightly by hand

3.7 Grown seedlings after 4th days

3.8 Grown seedlings after 15 days

3.9 Measurement of initial heart rate at rest for male and female subjects

3.10 Line diagram of manually operated six-row paddy transplanter

3.11 View of manually operated six-row paddy transplanter

3.12 Cutting of seedlings mats

3.13 Seedlings mats kept on the seedling tray by subject

3.14 Transplanting operation by male and female subjects with paddy transplanter

3.15 Transplanting operation by male and female subjects with hand

3.16 Modified handle for fitting the load cell

3.17 Forces measurement during transplanting operation

4.1 Heart rate of the male subjects during transplanting by manually operated six-row paddy transplanter

4.2 Heart rate of the female subjects during transplanting by manually operated six-row paddy transplanter

4.3 Heart rate of the male subjects during transplanting by hand

4.4 Heart rate of the female subjects during transplanting by hand

4.5 Comparison of heart rate and energy expenditure rate between male and female subjects during transplanting operation by paddy transplanter

4.6 Comparison of heart rate and energy expenditure rate between male and female subjects during transplanting operation by hand

NOMENCLATURE

Abbildung in dieser Leseprobe nicht enthalten

CHAPTER I INTRODUCTION

Rice is the staple in the diet for much of the world. It runs a close second to wheat in its importance as a food cereal in the human diet. About 560 Million Metric Tons of rice is grown annually compared to 600 MMT for wheat, 300 MMT for oil seeds and 900 MMT for coarse grains. Of the 560 MMT produced almost 60 % is grown and consumed in China and India. The leading producers of rice are (in order) China, India, Indonesia, Bangladesh, Vietnam, Thailand, Burma, Japan, Philippines, Brazil and United States.

India is one of the major rice producing and consuming countries in the world. Rice is also the single most important crop in Indian agriculture. It is produced in all the states of the country and is part of the staple diet of a very large section of the Indian population. Paddy is grown in about 44.55 Mha in India (22.8 % of the total cropped area) and has the largest acreage in the world after China. It is the staple food for two-thirds of Indian population and provides 20-25 % of agricultural income (De and Babu, 2004). The state of Gujarat has a unique agro climatic condition. The progressive and hard working farmers produce wide variety of agricultural produces. The major crops include rice, wheat, maize, oilseeds, cotton, fruits and vegetables and spices. The yield of rice in Gujarat is 1549 kgs ha-1 (Anonymous, 2002).

Paddy is generally grown by transplanting under wetland conditions or direct seeding depending upon the availability of water. Inspite of considerable progress made in the area of chemical control of weeds for directly sown paddy, transplanting remains the most common method of paddy sowing. Transplanting essentially refers to the planting of 20-35 days old and 20-30 cm high seedlings raised in nurseries and uprooted for transplanting either manually or mechanically (Mehta et al., 1990). Transplanting with recommended plants/hill density has a number of advantages like, the time that crop occupies the land is reduced by 3-4 weeks, helps the plant a better start over the weeds allows better water management practices, permits optimum plant spacing which is critical for higher yields, ensures uniform ripening of the crop, helps in better weeding and intercultural operations (Singh, 1971).

Presently in India, transplanting of the paddy crop completely depends upon manual labour. Human energy is predominantly used in most of the rice farming operations starting from seedbed preparation to threshing. Full or partial mechanization has become a necessity in rice cultivation where manual labour input is very high from planting to harvest. Human labour is the single costliest input in rice cultivation, it is estimated that nearly 145 man-days are required per hectare of rice. Among these planting, crop care and harvesting accounts for 21.0, 24.2 and 18.1 % of total human power requirement respectively. Inspite of high labour requirement of about 200-250 man-hours required for random transplanting of one hectare of an area, the correct plant population is not achieved. The contract labour generally employed for this operation, transplant the seedlings randomly and at spaces for wider than the recommended ones (Garg et al., 1981). Also, the scarcity of labour during peak season of transplanting poses a big problem to complete the transplanting operation in time. Delay in transplanting beyond the recommended period causes progressive decrease in the yield. The inadequate number of seedlings per hectare transplanted by manual labour and delay in transplanting due to labour shortage during peak transplanting season have pushed the demand to mechanize this operation. Apart from saving in time and cost of transplanting and removing the human drudgery, it can give desired plant density. Also, one can transplant the crop in time at no extra cost making weeding and intercultural easier.

In the Indian context, mechanization to fully substitute human labour may meet with social dissension. But mechanization as a tool to reduce drudgery and to increase labour efficiency and productivity will be welcome. Operational holdings in the size group of 0.2 ha and the small size fragmented parcels of land pose operational problems for large machinery in rice farming. Nevertheless, mechanization in rice farming has taken roots in this country in operations where timeliness and efficiency are hit by high cost and shortage of human labour and where labour efficiency suffers due to drudgery. Here mechanization is contemplated to increase production, improve labour efficiency and reduce the cost of operation.

Manual paddy transplanting is a labour intensive operation comprising nursery raising , uprooting of the seedlings, transporting and transplanting the uprooted seedlings in the main fields, with a total labour requirement of about 250-320 man-hour ha-1 (Jain and Philip, 2003). High labour demand during the peak periods adversely affects the timeliness of operation, thereby reducing the crop yield. To offset these problems, mechanical transplanting is the solution. A number of manually operated farm tools and equipment have been designed and developed for different agricultural operations in the country by the research institutes. These farm tools/equipments are designed mostly for men workers, though in Indian agriculture, women are actively engaged in almost all the farm operations (Singh et al., 2004). There are more than 200 million agricultural workers of which more than 35 % are female workers (Gite and Singh, 1997). These workers are exposed to all kinds of machine and environmental hazards. Mechanization not only changes the structure of labour in agriculture, but also influences the nature of the workload. Farm implements and machinery hitherto have not been ergonomically designed. Hence there is an urgent need to study the ergonomic aspects to quantify the drudgery involved in agricultural operations especially in rice farming. Such designs of implements wound not only minimize drudgery of the labour but also increase productivity at reduced expenditure levels. Thus, investigation on ergonomical evaluation of paddy transplanter can provide a rational basis for improvement in equipment design for more output and safety.

Physiological cost of work is influenced by the health of the operator, nutrition, basal metabolic rate (BMR) and energy expended while working. Systematic efforts to evaluate human energy expenditure for performing different operations are yet to be made. These measurements are also important from the safety point of view because whenever physical capacity of a person in exceeded, it is bound to cause considerable fatigue and decrease in the degree of alertness of the subject, making the operation unsafe. Thus, studies on human energy measurements in agricultural operations can provide a rational basis for recommending methods and equipment for performing the agricultural operations more effectively and safely. Heart rate bears a linear relationship with the intensity of physical exercise and oxygen consumption especially if the steady state is reached. Moreover heart rate monitor can measure instantaneous heart rate continuously over a period of time under field condition. Therefore, several research workers have used heart rate for assessment of physical and physiological workload on the workers (Le Blanc, 1957; Suggs & Splinter, 1961). Keeping in view the above aspects, this study is carried out with the following major objectives.

Objectives

1. To work out physiological cost of the subjects while performing operation with six-row paddy transplanter.
2. To determine the rest pause required for the operation of paddy transplanter.
3. To compare the energy requirement in transplanting of paddy by manually operated six-row paddy transplanter and with the help of hand.

CHAPTER II REVIEW OF LITERATURE

The literature emphasizes mainly on physiological evaluation, rest pause, energy requirement and force measurement of agricultural equipments have been reviewed. A brief review of these studies is presented as below.

2.1 Physiological Evaluation

Christensen (1953) and Zander (1969) suggesting the physical workload on the basis of energy expenditure and heart rate is given below:

Table 2.1: Grade of physical work based on EER, HR and OCR

Abbildung in dieser Leseprobe nicht enthalten

It was therefore evident that estimation of EER by measuring HR under field or laboratory conditions would be an acceptable and fairly accurate method for operator’s performance assessment.

Dupuis (1959) reported that the energy expenditure of tractor driving varies from 1-4 kcal min-1 depending on the particular agricultural task performed. Grandjean (1963) reported that EER can be measured indirectly by measuring the OCR since the two are interrelated. When 1 l of oxygen is consumed in the human body, there is on an average, a turnover of 4.8 kcal of energy.

Morehouse and Miller (1963) concluded that a period of 3-5 minutes is considered suitable for pulse rate to stabilize depending upon the nature of exercise. Tomilson (1970) reported that a rapid increase occurs in the heart rate at the start of work and highest increase takes place within the first 15 seconds of exercise and it gradually becomes constant.

Heart rate bears a linear relationship with the intensity of physical exercise and oxygen consumption especially if the steady state is reached (Karpovich, 1966; Le Blanc, 1957; Suggs & Splinter, 1961). Moreover heart rate monitor can measure instantaneous heart rate continuously over a period of time under field condition and right at the place of work in the field. Therefore, several research workers have employed this technique as a reliable index for energy requirement, postural studies and for other working environment parameters (Berger, 1967). Vos. (1973) indicated that bending posture followed in the paddy transplanting practices caused cumulative trauma disorder (CTD) and required an extra energy of about 2 kcal min-1 and increased the heart rate by 30 to 35 beats min-1.

McCormick (1976) reported that the posture of workers while performing some tasks is another factor that can influence energy requirements. Transplanting in bending posture required the highest energy than any other posture.

Astrand & Rodahl (1977) and Grandjean (1982) reported that energy consumption and cardiac set limits to the performance of the physical work and these two functions are often used to assess the degree of severity of a physical task. Table 2.2 gives the classification of physical work according to energy expenditure.

Table 2.2: Classification of physical work according to severity of workload

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Pawar (1978) investigated the human energy requirements for power tiller operation and reported that 5.5 % of additional human effort was required for walking in puddled soil. The contribution of posture towards human energy expenditure was in the range of 8.91 to 11.81 %. Saha et al. (1979) reported that acceptable workload for average young Indian worker varies between 30-40 % of an individual maximum aerobic power under comfortable environment conditions. The corresponding heart rate and energy expenditure reported by the author were 110 beats min-1 and 18 kJ min- 1 respectively.

He also reported that the limit for acceptable workload (AWL) for Indian workers is considered as 14.6 kJ min-1. He developed following relationship between energy expenditure rate (EER) and heart rate (HR).

Abbildung in dieser Leseprobe nicht enthalten

Sengupta et al. (1979) found a relationship between pulse rate and EER during graded work at different temperatures. Various investigators have studied the effect of muscular work and environmental temperature on physiological reactions and metabolic responses indicating the existence of controversial variation in each study. As environmental temperature is increased, OCR during work has been reported to decrease. The energy expenditure considering the environmental temperature can be calculated as follows.

For HR below 95 beats min-1

1) Y= -13.4910 + 0.2924 * X (22 °C)
2) Y= -15.1261 + 0.2843 * X (30 °C)
3) Y= -12.9313 + 0.2493 * X (37 °C)

For HR above 95 beats min-1

4) Y= -22.1481 + 0.4373 * X (22 °C)

5) Y= -17.9534 + 0.3402 * X (30 °C)

6) Y= -18.3744 + 0.3332 * X (37 °C)

Where, Y= Energy Expenditure Rate (kJ min-1)

X= Pulse Rate (beats min-1)

Nag and Dutt (1980) concluded that, the transplanting of rice by hand demanded higher energy. Walking in a puddled field itself required 22 % more oxygen uptake and the heart rate was higher by 11 beats min-1. As the transplanting operation needs to be done in a puddled field, the workers have to immerse their feet in mud (mid calf to knee depth) during their activities and it takes about 240 man-hours to plant one-hectare area. Nag (1981) carried out ergonomic evaluation of paddy transplanter and he observed that the subjects require the energy expenditure as 13.00 kJ min-1. The manually operated paddy transplanter is ergonomically evaluated (Anonymous, 1984). The average heart rate and oxygen uptake of the subjects varied in the range of 120 to 130 beats min–1 and 1.3 to 1.7 l min-1 respectively. They concluded that around 3000 to 3600 kcal of energy is required for the operation in day of 8 hours.

Baqui and Latin (1982) studies human energy expenditure in rice transplanting using IRRI manual rice transplanter in comparison with traditional hand transplanting by indirect calorimetry. The maximum energy expenditure in machine and hand transplanting were 3.79 and 3.09 kcal min-1 respectively. De and Sen (1986) ergonomically evaluated ploughing operation in paddy cultivation. Energy requirement in this task was found to be 14.7 kJ min-1.

Kathirvel et al. (1991) investigated the energy expenditure pattern of selected subjects for puddling with power tillers and found that the average energy expended by the subjects varied from 3.81 to 5.74 kcal min-1. Gite (1992) carried out egronomic evaluation of manual weeders. The mean oxygen consumption during the operation varied from 0.499 to 0.625 l min-1 for different weeders.

Gite and Singh (1997) suggested that for 8 h duration, a work requiring oxygen consumption less than 0.7 l min-1 is considered as the acceptable one. The corresponding heart rate for this oxygen consumption rate will be about 110 beats min-1.

Ergonomical evaluation of paddy transplanter was carried out and they observed that the mean heart rate and energy expenditure of the male subjects were 136.03 beats min-1 and 24.45 kJ min-1. The corresponding oxygen consumption for this heart rate was 1.171 l min-1 and the operation of paddy transplanter was graded as ‘heavy’ Anonymous (2002).

Physiological study was conducted to work out the physiological cost of the agricultural operations like spraying with knapsack sprayer, weeding (with sickle and manual weeder) seedbed preparation with Khampali, m anual harvesting of groundnut, clod breaking with spade, ploughing with tractor mounted MB plough, cultivating with tractor-mounted cultivator, harrowing with bullock drawn blade harrow and sowing of groundnut seeds by dibbler and it was ranged from 8.00 to 22.27 kJ min-1. On the basis of that grading of energy cost of the work can be made and accordingly rest can be given to the workers to get higher output (Anonymous, 2004).

Singh et al. (2004) ergonomically evaluated manually operated fertilizer broadcaster with eleven farmwomen workers to assess its suitability for farmwomen. They found that the mean working heart rate and DHR was 146.7 ± 13.3 beats min-1 and 65.4 ± 18.8 beats min-1 respectively with its full hopper capacity (9 kg urea).

2.2 Rest Pause

Lehmann (1958) stressed upon the need to figure out the reasonable ceiling of energy expenditure over the period of conventional working day. He found that the maximum energy output, a normal man can afford in long run, is about 4800 kcal day-1 subtracting his estimate of basal and leisure requirements of about 2300 kcal day-1, leaves a maximum of about 2500 kcal day-1 available for the working day. Although he proposed a maximum of about 2000 kcal day-1 as a normal load. In this connection, Murrell (1965) presented the following formula for total amount of rest required for a given work/activity, depending upon the average energy cost

Abbildung in dieser Leseprobe nicht enthalten

Where, R= Rest time (min);

T= Total working time (min) and

K= Average kilocalories per minute of work and value 5

kcal min-1 adopted as standard. The value 1.5 is an approximation of resting level in kcal min-1.

Murrell (1969) concluded that EER is difficult to measure directly, so in practice the physiological cost of work is generally measured in terms of OCR is given as

Abbildung in dieser Leseprobe nicht enthalten

Rest pause is calculated as

Abbildung in dieser Leseprobe nicht enthalten

Where, R= Rest (min);

T= Total working time (min);

E= EER during working task (kcal min-1);

B= EER during rest (=1.5 kcal min-1) and

A= Average level of EER (=5 kcal min-1)

(=33 % of max. aerobic power)

Inns (1998) reported that the rate of energy consumption 250-300 Watts can not be sustained for very long. If the rate of energy consumption is known then the required rest period can be estimated from equation

Abbildung in dieser Leseprobe nicht enthalten minutes per h of work

Where TR is the required resting time and P is the actual rate of energy consumption in Watts.

Beynon et al. (2000) reported that workers in physically demanding occupation require rest breaks to recover from physiological stress and biomechanical loading. Physiological stress can increase the risk of developing musculoskeletal disorders and repeated loading of spine may increase the potential for increasing back pain.

2.3 Energy Requirement

Singh and Gangwar (1999) reported that 70 % labour and 48 % cost may be saved by using mechanical transplanting as compared to hand transplanting. Mechanically transplanted seedling gave 13.34 % higher yield compared to hand transplanted and 50 % higher yield compared to direct seeded fields. The benefit/cost ratio for mechanically transplanted fields (2.55) was the maximum followed by 2.04 for hand transplanted and 1.88 for direct seeded fields.

Karunanithi and Tajuddin (2003) studies the energy expenditure of male workers varied from 2.4 to 4.9 kcal min-1 whereas that of female workers varied from 2.3 to 3.5 kcal min-1. Male workers consumed 2 to 10 % more energy than female workers for performing the same task.

Shukla et al. (2003) recommended that the developed manually operated six-row paddy transplanter having field capacity 0.38 ha day-1 costing Rs. 7500/- and giving Rs. 1480/- per hectare saving in transplanting cost should be released for the benefit of farmers.

Satapathy et al. (2004) studies six female subjects in the age group of 20-40 years were selected for ergonomical evaluation in manual transplanting operations. The average working heart rate and oxygen uptake was observed to be minimum 115.8 beats min-1 and 0.63 l min-1 in random transplanting and 128.7 beats min-1 and 1.16 l min-1 in four-row transplanter. It was observed that the VO2 maximum of the female subjects varied from 1.58 to 1.88 l min-1 and in four-row transplanter the oxygen uptake of all subjects was more than 50 % of their VO2 maximum.

Sharma and Singh (2004) developed a mat type nursery-raising device for rice transplanter. It is reported that 72.02 and 33.33 % saves the time and labour respectively, over the manual method of raising type nursery. The cost of raising mat type nursery for 1 ha was Rs. 299.50 with the developed device where as it was Rs. 1608.75 with manual method.

Sivaswami and Anie John (2004) found that nearly 85 % of labour cost was reduced by the introduction of paddy transplanters compared to manual transplanting. The labour shortage has been overcome by the use of transplanters and also the total cost of paddy cultivation was reduced by 50 % as Japanese and Cono weeders were also used for weeding. The yield in machine-transplanted fields had shown an increase of 10-18 % because of maintaining the correct hill density, no. of seedlings/hills and depth of planting, increased tillering, easy wind passage and shock free transplanting of seedlings.

2.4 Force Measurement

For better muscular efficiency, the dynamic effort of a repetitive nature should not exceed 30 % of maximum (Van Wely, 1970). Therefore, the tools should be such that the operator does not have to exert more than 7.5 kg push or 6.0 kg pull.

Martin and Chaffin (1972), Ayoub and McDaniel (1974), and Chaffin et al. (1983) found that the height at which push-pull forces were applied was the most important variable in affecting the force output. Chaffin et al. reported volitional postures during maximal push and pull exertions in sagital plane of 67 cm, 109 cm, and 152 cm heights. They concluded that foot placement, handle height and body postures all affected the push-pull strength.

Gite and Yadav (1985) manually operated weeders comprise of actuating blade attached to the frame with a tyne, a handle and a depth control device. The muscles of the operator provide adequate power to operate the tool either with a pulling, pushing or swinging action. The criteria for ergonomically comfortable design of weeder include design within the capability of human worker, use of proper posture of the operator for most efficient performance of the tool at lesser fatigue and suitability of the tool for workers of varying age and body dimensions. The strength of female workers is approximately 50-67 % of male strength. Males can exert up to 500 N force and female about 250 N. This is mainly due to females having smaller grip size and muscles.

Singh (2004) studied that the relation between subject and handle height and stated that the effect of subject height on the handle height of wheel hand hoe was checked. Hence, for this a table was prepared for height of subjects, force applied and minimum height of handle from the ground at which a subject applied minimum force shown in Table 2.3.

Table 2.3: Subject height Vs handle height from ground at point of minimum force

Abbildung in dieser Leseprobe nicht enthalten

He also reported that the maximum force, which the muscle can exert, depends upon weight and age of the operator. The peak of muscle power for both men and women is reached between the age of 25 and 35 years. Older workers aged between 50 and 60 years can produce only about 75–85 % as much muscular power. The weeders are to be operated by male as well as female workers and the age group ranges from 15-60 years. Maximum push and pull values are 25 and 20 kg respectively. Also, for better muscular efficiency, the dynamic effort of a repetitive nature should not exceed 30 % of the maximum. In the design, the operator does not have to exert more than 7.5 kgf push or 6 kgf pull. Unavoidable static effort should be reduced to not more than 15 % of the maximum i.e. about 3.75 kgf. In the operation of push/pull type wheel hoe, the frequency of movement ranges from 30–50 strokes per minute. Very high frequency may lead to excessive energy cost and rapid exhaustion of the worker whereas very low frequency may result in poor work output.

CHAPTER III MATERIALS AND METHODS

This chapter deals with the description of materials used, procedure and methodology involved in determining physiological response, rest pause, energy requirement and force measurement during paddy transplanting operation.

3.1 Selection of Subjects for the Transplanting Operation

Selection of subjects plays a vital role in conducting the ergonomic studies. Three male and three female subjects were randomly selected for the study. The subject should be medically fit to under go the trials. They should also be a true representative of the user population in operation of paddy transplanter. For the selection of the subjects, age is the main criterion was used. The age group of the subjects varied in the range of 25 – 35 years because they usually attain their maximum strength level between this age (Gite, 1997). The related anthropometric dimensions of the selected subjects are discussed under section 4.1. Some of the anthropometric data of the subjects used in this study are furnished in Table 3.1.

3.2 Growing of Seedlings

Seedlings were grown on raised bed in 200 x 100 cm wooden compartment. First the ordinary plastic sheets were laid on the raised surrounded by open ditch and the wooden frames were kept on sheets (Fig. 3.1). Thereafter, the soil, FYM and sand mixture prepared 4:1:1 proportion respectively and water was added to it to make paste which was placed over the plastic sheet up to 1.5 cm depth (Fig. 3.2 & 3.3). A set of pregerminated seeds is shown in Fig. 3.4 and pregerminated seeds are placed on a plastic surface to form a layer (Fig. 3.5). Pregerminated seeds than pressed slightly by hand for uniform their layer (Fig. 3.6). Water was sprinkled very frequently for three days to avoid any crack in the soil. From forth day, the open channel around beds was filled upto the level to maintain 2 cm water above the surface. The quality of seedlings was good and it should be better if seedlings of 12 to 15 days of age preferred (Fig. 3.7 & 3.8). The complete details of the seedlings are depicted in Table 3.2.

Table 3.1: Anthropometric dimensions of the subjects

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Fig. 3.1 Ordinary plastic sheet laid on raised bed with wooden frame

Fig. 3.2 Paste of soil, FYM and sand

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Fig. 3.3 Paste placed over the plastic sheet

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Fig. 3.4 Pregerminated seeds

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Fig. 3.5 Pregerminated seeds placed uniformly over the plastic sheet surface

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Fig. 3.6 Surface press slightly by hand

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Fig. 3.7 Grown seedlings after 4th days

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Fig. 3.8 Grown seedlings after 15 days

Table 3.2: Seedlings conditions

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3.3 Preparation of the Field for Transplanting

For the ergonomic evaluation of the transplanter, the size of the test field of 21 x 20 m was chosen. The soil texture was having 62.86, 21.16 and 8.83 % clay, silt and sand respectively. The field was prepared with MB plough and then it was flooded with water. After a period of 24 hours, the field was puddled thoroughly using power tiller operated rotavator. The puddle field was leveled using a bullock drawn wooden leveler. The leveled field was left undisturbed for natural settlement of soil particles forming a relatively impermeable layer to retain water on the surface. A thin layer of water was maintained in the field for conducting the trial with manually operated paddy transplanter and hand transplanting. The details of field conditions are given in Table 3.3.

Table 3.3: Field conditions

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3.4 Transplanting of Seedlings

Manual paddy transplanting is a labour-intensive operation comprising nursery raising, uprooting of the seedlings, transporting and transplanting the uprooted seedlings in the main field, with a total labour requirement of about 250-320 man-hour ha-1 (Jain and Philip, 2003). High labour demand during the peak periods adversely affects the timeliness of operation, thereby reducing the crop yield. The steady drift of agricultural labour to industrial sector is adding more to the woes of the rice farmer. Because of drudgery and notion that the farm operations are below the dignity, labour availability, in general, has decreased considerably in farm operations. To offset these problems, mechanical transplanting is the solution. Many transplanter were developed in the past involving the use of traditionally grown root washed seedlings for mechanical transplanting. However, on farm experience had shown that these traditional root washed seedlings were not successful with mechanical transplanters, due to machine related problems. Seedlings were grown on the raised bed in wooden compartment. Seedlings were transplanted by manually operated six-row paddy transplanter and also by hand transplanting. Fig. 3.9 shows the heart rate recording of the subjects during rest and which is presented in Table 3.4.

Table 3.4: Initial heart rate of the subjects at rest

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(a) Male

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(b) Female

Fig. 3.9 Measurement of initial heart rate at rest for male and female subjects

3.5 Manually Operated Six-row Paddy Transplanter

The paddy transplanter developed at Department of Soil and Water Engineering, Navsari Agricultural University, Navsari is a manually operated six-row paddy transplanter for transplanting of mat type paddy seedlings (12-15 days old) in the rows. Six sets of seedlings mats can be kept on the seedling tray of this machine and the operator pushes the handle to enable the picker to pick the pinch of seedlings with soil in the tray in its downward movement and place the seedlings in the puddle soil. As the handle is lifted back, the picker arm is also taken back from the soil by following the different path thus completing one stroke of operation. The operator walks backward as he pulls forward the transplanter for the next stroke. The distance between two rows is 20 cm and the distance through which the transplanter is moved forward in each stroke of operation decides the distance between two hills within a row. The transplanter is light in weight and can be carried by a single person comfortably. The line diagram and view of the manually operated six-row paddy transplanter is shown in Fig. 3.10 & 3.11. The specification of the paddy transplanter is furnished in Table 3.5. The performance of the paddy transplanter in the puddle field is presented under section 4.2.

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Fig. 3.11 View of manually operated six-row paddy transplanter

Table 3.5: Specifications of the transplanter

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[...]

Excerpt out of 60 pages

Details

Title
Ergonomic Evaluation of Manually Operated Six-Row Paddy Transplanter
College
Junagadh Agricultural University
Course
Agril Engineering
Authors
Year
2005
Pages
60
Catalog Number
V437934
ISBN (eBook)
9783668781986
Language
English
Notes
Human energy is predominantly used in most of the rice farming operations starting from seedbed preparation to threshing. Mechanical transplanting is the solution of better mechanization in paddy crop. For that farm implements and machinery have been ergonomically designed which minimize drudgery of the labour and increase productivity at reduced expenditure levels which can provide a rational basis for recommendation of methods and and improvement in equipment design for more output and operator’s comfort and safety. Manually operated paddy transplanter work satisfactorily.
Tags
ergonomic, evaluation, manually, operated, six-row, paddy, transplanter
Quote paper
Ph D Dr Rajvir Yadav (Author)Mital Patel (Author), 2005, Ergonomic Evaluation of Manually Operated Six-Row Paddy Transplanter, Munich, GRIN Verlag, https://www.grin.com/document/437934

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