Design of Weeder

Presented byMilufarzana (0805046)Jannat Yasmin (0805057) Md. Raju Ahmed (0805069)

Design, Development and Design, Development and Evaluation of a Push Type Evaluation of a Push Type

Manually Operated Cono WeederManually Operated Cono Weeder

Introduction Bangladesh is an agricultural country. The future economic

development of the country will depend largely on the progress made and goals achieved in the agricultural sector during last decades.

Weeding is one of the most important farm operations in crop production system.

In Bangladesh, this operation is mostly performed manually that requires higher labor input and also time consuming process.

Weeding is generally done 15-20 days after sowing. Delay and negligence in weeding operation affect the crop

yield. Timely weeding is very much essential for a good yield and this can only be achieved by using mechanical weeders.

At present, more than 15 different designs of weeders are available in Bangladesh.

All these designs are locally made and region specific to meet the requirements of soil type, crop grown, cropping pattern and availability of local resources.

These locally manufactured weeders do not maintain adequate design for minimum force requirement and either suffering with less penetrability or sinking in the soft soil.

The proposed design of the weeder incorporate cone shaped with blades on either side will reduce force requirement and ensure proper penetration in the soil.

Scope of the Study

Objectives

Considering the problems stated before the following specific objectives were formulated to give proper direction of the study:

1. To design and develop a push type manually operated cono weeder.

2. To determine the technical performance of the weeder in the rice field.

3. To determine the economic performance of the weeder in the rice field.

Review of Literature Islam et al (1991) designed a mechanical weeder for rice

which is reported to work better than the Japanese weeder in Bangladesh soil. It requires less power to operate than the Japanese weeder. It worked very well on wet soil and a field capacity of 0.35 hectare per hour.

Haq and Islam (1985) have reported that in low land rice the cost of manual weeding was 21.6% of the total production cost.

Dedatta (1981) reported that the yield loss due to weeds was 11.8% in Asia.

Biswas (1990) reported that mechanical weed control not only uproots the weeds between the crop rows but also keeps the soil surface loose, ensuring better soil aeration and water intake capacity.

Materials and Methods

Materials Required

The following materials were used to fabricate a push type weederi. M.S. sheet (16 SWG)

ii. Steel pipe (1" & 1/2"Ø)

iii. Steel blade sheet (4'-4"× 2)

iv. Bearing and bearing cover

v. M.S. rod(1/2"Ø)

vi. M.S. bar

vii. Nuts and bolts

Materials and MethodsMajor components Float: It was made of M.S. sheet and the length of the

sheet was 31 cm and the width was 14 cm. Cone with blades: It was made of M.S. sheet (16 SWG)

and the larger and smaller diameter of the cone was 14 cm and 6 cm respectively. The blades were made of steel blade sheet (4'-4"×2).

Main frame: It was made of steel pipe which diameter was 2.5 cm. The height of the main bar from the middle point of the float was 25 cm.

Handle: It was made of square bar which was 2.5 cm and length was 165 cm.


Fig. Photographic view of Push type manually operated cono weeder


Fig. Isometric view of Push type manually operated cono weeder


Fig: Top view of float

Fig: Front view of float

Fig: Photographic view of float


Fig. Front view of cone with blades Fig. Side view of cone with blades

Fig :Photographic view of cone with blades


Fig. Top view of main frame

Fig. Front view of main frame

Fig. Photographic view of main frame


Fig. Top view of handle Fig. Photographic view of handle

Materials and MethodsWeight Measurement: Weight of the weeder was measured at the workshop in

the Department of Farm Power and Machinery by using balance and data were recorded.

Fig. Photographic view of weight measurement

Materials and MethodsPushing Force Measurement: The force requirement of operation was determined in

the field using spring balance and three person involved in the test.

Fig. Photographic view of pushing force measurement

Materials and MethodsTechnical Efficiency of Cono Weeder

i. Weeding efficiency: The weeding efficiency was computed by using the following expression:

%100

ur

reff WW

W

Where,

ηeff= Weeding efficiency, %

Wr= Number of weeds removed by the weeder/ m2

Wu= Number of weeds left in the field after weeding

operation/ m2

Materials and Methodsii. Percent of Breakage: The percent of breakage of plants was

computed by using the following expression:

%100t

bb P

P

Where, ηb= % of breakage of plants Pb= Number of plants broken in the row after

weeding operation Pt= Total number of plants in the row.


iii. Field capacity: Field capacity of weeder was computed by using the following expression:

T

AE fc

Where, E

fc= Field capacity, ha/hr

A= Average area covered by the weeder, ha; T= Total time taken for weeding operation, hr.

Materials and MethodsOperating cost of Cono WeederMachinery cost consists of:(a) fixed cost-Depreciation, interest, taxes and insurance; (b) variable cost- labor and repair and maintenance.Fixed cost Fixed costs are fixed in total, but decline per ha, as the annual use of

machine is increased (Barnard & Nix, 1979).Variable cost The variable cost is one, which changes when the level of output alters.

Operating cost: Operating costs in, Tk/ha= Fixed cost + Variable

cost For determining operating cost (Tk/ha) of manual operation only the

number of man-days and labor rates were considered

RESULTS AND DISCUSSIONS

Weight and Pushing force required for the weeder The weight of the push type cono weeder was found 8.61 kg. The average pushing force of weeder was 56.24 N.

Obs. No

Pulling force (kg)

Pulling angle

Pushing angle

Pushing force, N

Average Pushing

force

1. 5 300 250 46.87

56.242. 6 300 250 56.24

3. 7 300 250 65.62

4. 6.5 300 250 60.45


Weeding Efficiency : Average weeding efficiency was calculated from six replications . The average weeding of weeder was found 63.41%

Obs. No Row Spacing, (cm)

Effective width coverage, (cm)

Weed population (W1)/m2 before weeding

Weed population (W2)/m2 after weeding

Weeding efficiency

%

Average weeding efficiency

%

1 18 13.5 84 31 63

63.41

2 18 13.5 80 30 62.5

3 18 13.5 78 28 64

4 18 13.5 74 25 66

5 18 13.5 80 28 65

6 18 13.5 75 30 60


Percent of breakage : Average percent of breakage was calculated from six observations. The average percent of breakage after weeding operation was found 5.04%.

Obs. No. Total no. of plants in 1m row before weeding

No. of plants broken in 1 m row after weeding

Percent of breakage

Average percent of breakage

1 378 19 5.02

5.04

2 360 15 4.2

3 350 18 5.14

4 355 20 5.63

5 375 23 6.13

6 345 14 4.1


Field capacity : The length and width of the field strip was 10 m and 10 m respectively. Time taken to cover the whole area was 5.08 min. The average field capacity of the weeder was found 0.012 ha/hr.

Obs. No. Length of the field strip, (m)

Width of the field strip, (m)

Time taken, (min)

Field capacity, ha/hr

1 10 10 5.08 0.012


Cost Comparison: The operating cost of weeder was 2145 Tk/ha where manually weeding cost

was 8000 Tk/ha Figure indicates that weeder is the best in terms of cost of operation and it is

more economical than manual operation.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Push type Cono Weeder Manually Weeding

Cos

t, T

k/ha

Fig. The cost operation of Weeder in comparison with manual operation

CONCLUSIONS AND RECOMMENDATIONS

Based on the findings and their interpretation the following conclusions

are drawn The weight of the push type cono weeder was found 8.61 kg. The pushing force required for push type cono weeder was found

56.24N The weeding efficiency of weeder was found 63.41%. The percent of breakage after weeding operation was found 5.04%. The field capacity of the weeder was found 0.012 ha/hr. The operating cost of the weeder was found 2145 Tk/ha.

Recommendations: Weight of the weeder should be reduced. It should be necessary to change the shape and arrangement of blade.