Select only your best rice seed with flotation and manual sorting

    | September 29, 2008

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    This week, we feature one of five scripts on rice production and seed management recently produced as part of a collaboration between Farm Radio and the Africa Rice Center (WARDA). In this script, the host interviews Chabi Adéyèmi, a research assistant at WARDA in Cotonou, Benin. Mr. Adéyèmi provides step-by-step instructions on how to use the floatation method to remove rice seeds that are unripe or have been damaged by insects. He also provides advice on sorting out grains with brown or black spots because, as our host explains, “healthy seed means good harvest.” The five new rice scripts have been mailed to Farm Radio partners as Package 85, and are available online at:


    Notes to Broadcaster

    For a good rice harvest, healthy seed is essential. Unripe grains or grains that have been damaged by insects are lighter in weight than healthy grains so they can be removed if you float them in water before sowing. Grains with black or brown spots are also unhealthy but these grains are not necessarily lighter so they can’t be removed by the floating method. In this case, farmers conduct manual sorting. This can be done immediately after harvest, before the seed is stored, or any time before the beginning of next season. Both methods help to improve the quality of seed.

    In the following radio interview Mr. Chabi Adéyèmi, a research assistant at the Africa Rice Center in Cotonou, Benin, provides listeners with step-by-step instructions about how to carry out floatation and manual sorting techniques.


    Host: Dear friends, good morning and welcome to your radio program about agriculture. Today’s program will be devoted to rice floating and sorting techniques.

    In the studio we have Mr. Chabi Adéyèmi who is a research assistant at the Africa Rice Center in Benin. He’s here to talk about two valuable techniques that will help you improve the quality of your rice seed.

    Mr. Chabi, sometimes, at planting time, farmers notice that their rice seed is damaged by insects, or that it’s not ripe. How can farmers improve the quality of their seed so they get a better harvest?

    Chabi: Well, to start, farmers can draw inspiration from practices used by farmers in Bangladesh to get better seed. One of these methods is called seed floatation.

    Host: Can you describe it for our listeners?

    Chabi: Of course. That’s why I’m here today!

    Host: We are listening to you then.

    Chabi: Okay, I’ll get started. After winnowing, you’ll see that partially filled grains and grains with holes are still mixed with the full, healthy grains. What you want to do is to separate out these bad grains by floating them in water.

    Host: That’s why this technique is called floatation!

    Chabi: Exactly. To use this method you have to follow a number of steps. First, you pour clean water into a container. I like to use a bucket. Then you add salt or urea to that water to change the specific density of the water.

    Host: How do you know when to stop adding the salt or urea?

    Chabi: Keep on adding salt, or urea, or even clay, until a freshly laid egg can float on the surface of the water. It was Bangladeshi women who made the discovery that when an egg could float to the surface of the water, the density of the water was just right for the seed floatation method. Next, add your grains to the water and mix everything by hand. After a while all the damaged and light grains will float to the surface of the water.

    Host: What about the healthy grains?

    Chabi: The healthy grains settle at the bottom of the container. Floatation is a practice that helps to separate good quality grains from bad quality grains. Don’t forget to mix salt, urea or clay with the water for a better effect. This brings up more of the unripe and light seeds to the surface.

    Host: Very good. Let me quickly summarize the technique for our listeners.

    The first thing you need is a clean container. It may be a basin, bucket or even a drum, isn’t it?

    Chabi: Of course. The container you select depends on how much seed you have.

    Host: Once you have the container, you pour water into it. Then you mix this water with enough salt or urea until a freshly laid egg can float on the surface of the water.

    Chabi: Yes.

    Host: After that you pour the seed into the water and stir it well. After a while all the light and insect-attacked grains will float on the surface of the water. The healthy grains however, settle in the bottom of the container. Then, after all this, what is the next stage?

    Chabi: Then you have to remove the damaged and partially filled grains that are now floating on the surface of the water. You can give them to the fowls.

    Host: What about the healthy grains that settled in the bottom of the water?

    Chabi: You remove them from the bottom of the container and you clean them twice, or three times in clean water. After that you can sow them.

    Host: I’ve noticed that sometimes there are seed grains that have black or brown spots on them. Will floating help remove those grains?

    Chabi: No, those grains are not necessarily lighter in weight, so they won’t float. In that case you have to do manual seed sorting.

    Host: Manual sorting?

    Chabi: Yes.

    Host: Doesn’t that take a lot of time?

    Chabi: Yes, it can, especially if you have a large quantity of seeds. But if the whole family helps, it goes quickly, and you don’t need to do it all in one day. You can do it gradually, in between two growing seasons.

    Host: Thank you, Mr. Chabi for your time today…for explaining the seed floatation and seed sorting techniques to us.

    Chabi: You’re welcome. It’s been a pleasure.

    Host: Dear rice farmer friend, don’t forget that healthy seed means good harvest. If you would like a copy of the video programs on rice seed cleaning, drying and conservation, you can contact [radio broadcaster should give name of local contact person or organization distributing rice videos].



    Note: Radio broadcasters can click on this link to see a list of rice video distribution sites or see the list that is included with this script package.

    Contributed by: Felix S. Houinsou, Rural Radio Consultant/Africa Rice Center (WARDA)
    Reviewed by: Paul Van Mele, Program Leader, Learning and Innovation Systems/Africa Rice Center (WARDA)

    Thanks to:
    -The International Fund for Agricultural Development (IFAD) for supporting participatory research with women rice farmers in lowlands, and for translating the rice videos into local languages.
    -The Bill & Melinda Gates Foundation and IFAD for supporting this script package.