A compilation of pictures of different weeder designs from many countries.
Here we see Madagascar farmers using a weeder ( houe rotative, rotating hoe) on their small rice plots. Although SRI soils are usually kept unflooded, the fields should be inundated before weeding to make the working of the soil easier and more thorough.
This is a very basic design, light, not expensive, though there is an alternative design, shown below, which is known as a ‘cono-weeder,’ where the working part is a ‘cone’ with ridges instead of an axle with ‘teeth’ as in this design.
Close-up of this basic weeder design.
This is a standard weeder design for a cono-weeder, developed by IRRI in the 1960s. It was introduced in Madagascar at that time, but its use has not been widespread with conventional rice growing. With SRI methods, there is a beneficial effect on crop yield beyond removal of weeds. Soil aeration has more effect on the growth and performance of young, widely spaced seedlings, well supplied with organic matter as well as aerated soil conditions.
This is an adaptation of the cono-weeder that has adjustable spacing. It can be set for 20x20 cm planting or for wider spacing up to 40x40 cm. It is fairly heavy, unfortunately, but by doing two rows at a time, rather than just one, farmers may find the greater difficulty of each pass to be ultimately labor-saving.
There will be no ‘one-best’ weeder design because soil and other conditions vary. But this model has been very popular in Sri Lanka and was received with enthusiasm by Madagascar farmers, because it is more light-weight and does not get clogged with weeds.
Close-up of Premaratna’s weeder design.
Picture provided by Peter Hobbs (Cornell, formerly CIMMYT) taken during visit in Northern India.
This picture is provided by Dr. Rena Perez, food security advisor to the Ministry of Sugar, who has been the volunteer national coordinator for SRI introduction in Cuba.
Picture provided by Dr. Rena Perez.
Picture provided by Shuichi Sato, team leader for Nippon Koei consulting team in Eastern Indonesia, showing Senegalese counterpart in JICA-funded National Rice Improvement Project, advised by Nippon Koei consulting team.
Gopal Swaminathan has been making a number of innovations to expand SRI concepts to different growing conditions and to other crops. This is his labor-saving innovation for weeding.
The estimated cost of this was $750, but it could be built more cheaply with large-scale production and with the Chinese motor used being purchased at wholesale rather than retail prices.
This is a close-up of the TNAU cono-weeder.
This was intended to be the cheapest possible weeder that could both remove weeds and aerate the topsoil. One person pulls it while a second person guides it. This would seem to be more labor-intense, but because this can be used effectively twice as fast as the standard one-person weeder, it does not require more labor per hectare. This will not necessarily be a final design, or useful for every farmer. Where labor is more expensive, probably other designs will be more economical. But this does give a good option where farmers have little capital and more labor.
This was built by Nong Sovann from Kandol village in Kampoth Spreu province, Cambodia, hammering bent nails into a wooden axle that is mounted in an iron-rod frame, with a ‘rake’ mounted on the back to maximize soil aeration. This is Sovann’s second design, an improvement over his model last year, and he says that he will improve (strengthen) the handle in next year’s design. He says that this weeder added $20 worth of yield to his small field, at a cost of $3 for materials and $0.75 for the labor required. He was able to do only one weeding because of lack of rain which would soften the soil enough to do more weeding. But even this one weeding Sovann said enhanced his crop yield very cost-effectively.
This slide is from a powerpoint prepared by Rogelio Lazaro, consultant with the National Irrigation Administration in the Philippines. Taking a ‘positive’ view of weeding here, SRI weeding is presented as good for people’s health -- by promoting aerobic exercise. It is of course also good for the health of the plant.
Picture of a weeder used in the Nepali terai, provided by Rajendra Uprety, District Agricultural Development Office, Morang District, Nepal.
Weeders for Use with SRI Alternative Designs to Save Labor Time and Energy
SRI recommends planting seedlings in a square pattern, so a mechanical hand weeder (rotary hoe or cono-weeder or some adaptation) can be used in two perpendicular directions. This process aerates the soil while turning weeds back into the soil to decompose.
The “Rotating Hoe” In Sri Lanka, this tool is called the “Japanese weeder.” In China, it is called the “wolf-fang weeder.”
Premaratna’s weeder can reduces weeding time from 5-10 days/acre to 1-2 days/acre, farmers say.
The ‘teeth’ of the new weeder, similar to the cono-weeder used in South India, do not get clogged with mud that needs to be removed, because the weeder is always pushed forward -- not pushed and pulled, forward and backward, as must be done with many other hand weeders for removing weeds and aerating the soil