Comparative performance of manual weeders under system of rice
intensification in Indo-Gangetic plains
Bikash Sarkar, S.K. Singh, Rakesh Kumar, J.S. Mishra*, Ajay Kumar, Vikash Yadav,
R.B. Reddy and B.P. Bhatt
ICAR-Research Complex for Eastern Region, ICAR Parisar, P.O: B.V. College, Patna, Bihar 800 014
Received: 19 January 2017; Revised: 19 March 2017
Key words: SRI, weeder, field capacity, weeding efficiency
Rice (Oryza sativa L.) is grown under diverse
ecologies ranging from irrigated to rainfed upland,
lowland and deep water. Traditional crop
establishment, i.e. puddling and transplanting,
requires large amount of water, energy and labour,
which are becoming scarce and expensive (Mishra
and Singh 2012). Weeds are considered to be one of
the major biotic constraints in achieving the higher
crop productivity as they cause a reduction of 10-
90% grain yield in rice field (Kumar et al. 2016).
System of Rice Intensification (SRI) is a modern and
alternative method of rice cultivation for reduced use
of seed, water and labour and to increase the crop
productivity. But this system is much infested with
weeds because growing under the limited water
management. Echinochloa spp., Cynodon dactylon,
Portulaca quadrifida and Cyperus spp. are the major
weeds associated with SRI. Herbicides were proved
effective but the continuous and indiscriminate use of
herbicides for a longer period may result in buildup of
problematic weeds and development of herbicide
resistance. Adoption of rotary or cono-weeder use in
SRI plays a significant role in improving the growth,
yield and economics of rice. Weed management with
improved tools not only uproot the weeds between
crop rows but also ensuring the better soil aeration.
Different type of weeders are available for weeding
but all these designs are location specific and
designed to meet the requirement of soil type, crop
grown, cropping pattern and availability of the local
resources (Goel et al. 2008). Hence, performance of
promising manual weeders was evaluated in SRI
under the middle Indo-Gangetic plains.
A field experiment was conducted at ICAR
Research Complex for Eastern Region, Patna (25o35'
N latitude and 85 o 04' E longitude) during the Kharif
2016 to study the performance of weeders i.e. cono
and Mandava weeder under the irrigated ecosystem.
Soil of the experimental plot was clay loam (sand:
23.69%, silt: 39.64% and clay: 37%). The climate of
experimental site was sub-tropical in nature exhibiting
high humidity and medium rainfall. The rice cv. ‘Pusa
1509’ (120 days duration) was used as test material.
The monthly mean maximum and minimum
temperature during the crop growing period ranged
from 29.2 - 35.40C and 12.2 - 23.20C, respectively.
The rice seedlings were transplanted at 25×25 cm
apart. The specification of the experimental weeders
is mentioned in Table 1.
*Corresponding author: email@example.com
Indian Journal of Weed Science 49(1): 82–84, 2017
Table 1. Specification of cono and Mandava weeder
Cono weeder Mandava weeder
Length : 2040 mm
Nominal width:194 mm
Working width: 125 mm
Height: 1120 mm
Width (handle): 500 mm
Type of handle: T-Type
Number of rotors: 02
Weight: 6.1 kg
Unit Cost: ` 1200/-(approx.)
Length: 1500 mm
Width (handle): 460 mm
Nominal width: 150 mm
Working width: 120 mm
Height: 1000 mm
Type of handle: T-Type
Number of rotors: 01
Weight: 5.1 kg
Unit Cost: ` 1000/-
Different test parameters were evaluated with formulae
given as below:
Theoretical field capacity Theoretical field capacity
was calculated with standard formula as suggested
by Mehta et al. (2005).
capacity field lTheoretica
by weeder covered Area
capacvity field Effective
Where, working width in m and speed in km/h
Effective field capacity: Effective field capacity is an
average output of the weeder per hour and calculated
from total area weeded in ha and the total work time
(Mehta et al. 2005).
Where, Area covered in m2 and total time in hr
Field efficiency: It is the ratio of the effective field
capacity to theoretical field capacity and expressed in
percent (%) and it was calculated by using the
formula as suggested by Mehta et al. (2005).
capacity field lTheoritica capacity field Effective
(%) efficiency Field
Where, W= theoretical width of cut in m, S =
speed of travel in km/h, E= field efficiency (%)
Weeding efficiency: Square loop (0.25 m2) was
randomly thrown to field and number of weeds
including in loop was counted before and after
weeding (Rangasamy et al.1993). Three sets of
observations were taken and weeding efficiency was
calculated as below.
broad-leaved weeds (BLW) Trianthema,
portulacastrun L., Euphorbia hirta L.; sedges viz.
Cyperus rotundus L. and Cyperus iria L. were
important weed flora during the experimentation. The
relative dominance of BLWs, grasses and sedges was
recorded as 84, 11 and 5%, respectively.
Field capacity of Mandava weeder was higher
(0.0168 ha/hr) than cono-weeder (0.0149 ha/hr). The
lower value of effective field capacity for cono-
weeder was also reported by Shakya et al. (2016).
The wide difference in the values of field capacity in
both the weeders may be due to difference in width of
cutting parts (blades) as well as forward speed.
Mandava weeder facilitates worker by providing easy
push and pull action to the implement as compared to
cono-weeder. Field efficiency was higher with
Mandava weeder (89%) as compared to cono-
weeder (87%). Higher field efficiency of weeder was
because of minimum time loss in turning and during
operation (Shakya et al.2016). Weed density of 84
and 96/m2 was recorded before weeding with the
cono-weeder and Mandava weeder, respectively
(Table 2). The maximum weeding efficiency was
found with Mandava weeder (88%) as compared to
cono-weeder (71%) which might be due to greater
soil contact and soil inversion capacity of the weeder.
The wide difference in the values of weeding
efficiency in both weeders may be due to difference
in shape of blades and depth of operation. The
average value of plant damage factor for cono and
Mandava weeder were obtained 7.58 and 6.17%
respectively, which was 30% lower in developed
cono-weeder reported by Shakya et al. (2016).
Involvement of man power was examined with
respect to weeder used in controlling weeds of rice
under SRI and it was noted that Mandava weeder
consumed the minimum man-days/ha (7.44).
Human energy: The highest human energy was
consumed by cono-weeder (131.39 MJ/ha) as
compared to Mandava weeder (116.65 MJ/ha). As,
cono-weeder required the highest energy, it was not
found to be economical in terms of eco-energetics
(Table 3). But Mandava weeder was not only proved
efficient in terms of eco-energetics but also useful in
completing weeding in lesser time.
Pushing force measurement: Result showed that
forces of 98o74' N and 68o64'N are required for 10
capacity Field E
(%) efficiency Weeding
Where, W1= number of weeds before weeding,
W2= number of weeds after weeding
Plant damage: It was calculated by counting the
number of injured plants and total number of plants in
sample plot and expressed in per cent (%) (Biswas
and Yadav 2004).
Where, Pd = Plant damage (%), A=Injured plant
(no.), B = Total no. of plant in sample plot
The human energy co-efficient 1.96 MJ was
considered as suggested by De et al. (2001)
Pushing force measurement: The force requirement
of operation was determined in field using spring
balance and three persons involved in test (Figure 1).
Spring balance was fixed between pulling wire and
one person pulled weeder, while another person
recorded data of spring balance and third person just
held handle of weeder along with line of action.
Table 2. Weed density (no./m2) and weed control efficiency (WCE) as affected by two weeders
(no./m2) Weed count (no./m2)
before weeding Weed count (no./m2)
after weeding Weeding efficiency
Cono-weeder 71.0 9.24 4.20 84 24 71
80.64 10.56 4.80 96 12 88
Figure 1. Pushing force measurement
Comparative performance of manual weeders under system of rice intensification in Indo-Gangetic plains
Major weed associated with crop was grasses,
broad-leaved weeds and sedges. Among grasses,
Echinochloa crus-galli (L.), Echinochloa colona (L.)
Link, Eleusine india (L.) Gaertn., Leptocholoa
chinensis (L.) Nees, Cynodon dactylon (L.) Pers.;
output recorded by Mandava weeder was 168 m2/hr
as compared to cono-weeder (149 m2/hr). During
weeding with cono and Mandava weeder, ÄHR was
27.6 and 24.4 beats/min, respectively. Energy
expenditure was 8.57 kJ/s and cardiac cost 11.15
beats/m2 for cono-weeder. However, in case of
Mandava weeder it was found 7.68 kJ/s and 8.71
beats/m2 of energy expenditure and cardiac cost,
respectively. Manduva weeder saved 21.88% cardiac
cost and increases efficiencd 10.38%.
Two weeding tools were evaluated in SRI.
Maximum weeding efficiency was recorded with
mandava weeder as compared to cono-weeder.
Mandava weeder consumed minimum man-days/ha.
Therefore, mandava weeder may be promoted at
farmer’s fields in wider scale as it reduces energy use
of small and marginal farming community of the
Indo-Gangrtic Plains of the Eastern India.
The senior authors sincerely acknowledge to the
‘Sir Jamsed Ji Tata Trusts’ Mumbai for technical and
financial support to conduct the present study.
Biswas HS and Yadav GC. 2004. Animal drawn weeding tools
for weeding and intercultural in black soil. Agricultural
Engineering Today 28 (1&2): 47-53.
De D, Singh RS and Chandra H. 2001. Technological impact on
energy consumption in rainfed soybean cultivation in
Madhya Pradesh. Applied Energy 70: 193-213
Goel AK, Behera D, Behera BK, Mohanty SK and Nanda SK.
2008. Development and ergonomic evaluation of manually
operated weeder for dry Land crops. Agricultural
Engineering International: The CIGR E-Journal. Vol. X.
Kumar P, Singh Y and Kumar R. 2016. Productivity,
profitability, nutrient uptake and soil health of boro rice as
influenced by cultivars and herbicides. International Journal
of Agricultural and Statistical Sciences 12(S1): 177-183.
Mehta ML, Verma SR, Mishra SR and Sharma VK. 2005. Testing
and Evaluation of Agricultural Machinery. Daya Publishing
House, Delhi-100 035.
Mishra JS and Singh VP. 2012. Tillage and weed control effects
on productivity of a dry-seeded rice-wheat system in a
Vertisol in Central India. Soil and Tillage Research 123: 11-20.
Sarkar B, Kumar R, Mishra JS and Bhatt BP. 2016. Comparative
performance of different weeding tools in winter maize
(Zea mays L.). Indian Journal of Weed Science 48(3): 330-
Shakya HB, Parmar MR, Kumpavat MT and Swarnkar R. 2016.
Development and Performance Evaluation of Manually
Operated Cono-Weeder for Paddy Crop. International
Refereed Journal of Engineering and Science 5(7): 6-17.
Pushing force (N)
Cono-weeder Mandava weeder
10 mm 98.74 89.38
Table 4. Pushing force vs. water levels in rice field
Table 5. Physical characteristics of selected male farmers
Physical characteristic Mean±SD
Age (yrs) 33.80±9.18
Height (cm) 167.80±3.96
Weight (kg) 66.60±4.28
Table 6. Performance of male farmers during field
Average working heart rate
Average heart rate during rest
(beats/min) 81.2±5.59 78.8±7.39
Δ HR ( beats/min) 27.6 24.4
Output ( m2/hr) 149 168
Energy expenditure (kJ/s) 8.57 7.68
Cardiac cost (beats/m2 area covered) 11.15 8.71
Reduction in drudgery (%) - 10.38
Increase in efficiency (%) - 21.88
Bikash Sarkar, S.K. Singh, Rakesh Kumar, J.S. Mishra, Ajay Kumar, Vikash Yadav, R.B. Reddy and B.P. Bhatt
Table 3. Human energy requirement for weeders in SRI
Cono weeder 67.04 131.39
and 30 mm water depth, respectively in cono-weeder,
while in mandava-weeder; they were 89.38 N and
61.14 N, respectively (Table 4).
Ergonomics Evaluation: Ergonomic study was
carried out with 5 male workers for weeding in SRI.
Anthropometric rod and weighing balance were used
to measure the physical characteristics and stop
watch for recording time. Polar Heart Rate Monitor
(RS-400, Finland) was used for recording heart rate
of subject. To evaluate the weeding through
ergonomic point of view, 5 workers in age group of
21 to 46 yrs were selected and average age as 33.8
yrs, body height of 167.8 cm and weight 66.60 kg,
respectively (Table 5).
Physiological stress of weeding was determined
on the basis of parameters i.e. heart rate during work
and rest, energy expenditure and cardiac cost of
work while performing activity (Table 6).
There was 10.4% increase in working
efficiency with usage of the mandava weeder. The