Assumptions:
Design of the modified rotary weeder is depends on field conditions, crop and soil types and energy requirement of the machine. The machine is to be powered by a 48 volt 750-watt motor which is operated by 48-volt rechargeable dry cell battery. Chain and sprocket arrangement is used for transmission of power. Motor speed is 700 rpm.
Design Process :
Power requirement of motor, chain and sprocket selection and design and arrangement of tines are needed to be considered in the design process. In modified version, power is provided to the wheel as same as the walking speed of human (50 rpm). The power supply on rotary shaft should be taken into consideration. There are two parts of the weeder, one is body and another is handle. Body part consists of motor, battery, reducer gearbox, wheel and rotary shaft but handle consists of auto switch and converter.
- Chain and sprocket selection:
Chain and sprocket arrangement was adopted for transmission of power. The chain, sprocket and shaft selection was based on Agricultural Machinery Management Data.
- Weeding Tines and Tines arrangement:
A j-shaped tine is designed on the shaft which is shown. Length and width of the tine is 80mm, curve angle of tine is 1200 and 18mm respectively. Dimension of the shaft is 245 mm and 73 mm respectively.
Machine Description
The powers to the rotary hoe are supplied from the motor through chain and sprocket. The most of the components of weeder were fabricated at the Farm Machinery and Post-Harvest Process Engineering Division, Bangladesh Agricultural Research Institute (BARI) while other standard components, such as motor and transmission elements were picked up locally and the parts were assembled at the same workshop.
Site and experimental condition:
The experiment was conducted at FMPE division research field of Bangladesh Agricultural Research Institute (BARI) and farmer’s field under OFRD Kishoregonj during kharif season 2019-20. The soil was clay loam and soil penetration was recorded before each treatment imposed.
Crop and weeds:
Maize
Hybrid Maize (Elite) was planted manually in the experimental plot (6.5 x 7 m each) with 60 cm row to row spacing and 25 cm plant to plant spacing. Each plot accommodated 6 rows. The planting date was 14th December, 2019. Density of weed was recorded before and after treatment imposed. The weed sampling was done randomly in middle three rows in 1.2 x 1 m quadrants. Width of cut is 20 cm, so three pass is done to cover 60 cm width. Number of plant damage is recorded and Inter plant weeds were removed by mechanical method.
- Fertilizer, Irrigation and earthing up
Fertilizer and irrigation was applied as BARI recommended dose. And earthing up for maize was done manually at 45 days after sowing.
- Experimental Design
The study included three treatments replicated four. The experiment was designed in Randomized Complete Block. The treatments were:
T1 - Weeding by BARI Battery Operated weeder at 15 and 30 DAT
T2 - Weeding by BARI push and pull weeder at 15 and 30 DAT
T3 - Manual Weeding at 15 and 30 DAT
T4 – Chemical Weeding by herbicide (Gramoxon-3ml/lit) spray at 15 and 30 DAT.
Statistical Analysis:
All statistical analyses in this experiment were carried out using statistical package “R 3.4.4” for Windows Version 2010. Analysis of variance (ANOVA), Coefficient of variance (CV) and least significant difference (LSD) between mean values were calculated at 5% significance level.