Wednesday August 20 2014

Sunn hemp may be toxic but it keeps soils fertile

By Lominda Afedraru

As seed companies in Uganda vie to supply farmers with quality seed for better yields and sufficient output, they are beginning to incorporate legume crops to fix nitrogen to improve on soil fertility.
One such a crop which some commercial farmers are growing in some parts of northern Uganda is sunn hemp or Indian hemp (Crotalaria juncea L.), an annual plant widely grown in the tropics.

Seed companies have imported this crop and supplied it to farmers to use as a means of crop rotation with the main aim of increasing soil fertility.

Sunn hemp is a cover crop grown in Africa and the other parts of the world to control weeds and pests such as nematodes as well as add nutrients to soil, prevent soil erosion, and contribute to a community of beneficial nematodes. In some areas, it is crushed and used as animal feed although scientists say its seeds are toxic, and therefore poisonous for human consumption.

One seed company in Uganda, which is growing sunn hemp at its seed multiplication farm in Nalweyo, Kibaale District is the Nalweyo Seed Company (Naseco).

This is part of an initiative by Naseco which has been producing seed for crops such as maize, in particular the Longe 10H hybrid variety that was released in 2010, rice, beans, sorghum and groundnuts.

Although sunn hemp was introduced in Uganda from Latin America, it has adopted well to the soils here, according to Dr George Bigirwa, senior programme officer, Alliance for Green Revolution in Africa (Agra). He led stakeholders from different parts of Africa on a tour of Naseco’s multiplication fields.

The Agra team is on a sensitisation drive in various countries on the importance of farmers embracing quality seed for better output. This, they say, can only be possible if the farmers work out modalities with seed companies by being outgrowers for seed in order to fulfill the market demand.

To increase output
With soil fertility decreasing in different parts of the country, it is prudent for farmers to adopt sunn hemp as an agronomic practice of crop rotation to increase fertility of the soil.

“Like we advise farmers to carry out crop rotation using other crops such as beans, groundnuts, green gram, sorghum and millet, which contain root nodules for nitrogen fixation, the same applies to the sunn hemp which has even more ability to fix nitrogen in the soil because its capacity to produce the nodules is high’” Dr Bigirwa explains.

He adds that farmers in the developed countries have been using this crop for a long time as a measure to increase on soil fertility. So, he urges Ugandan farmers to do the same to increase on their output.

Share with others
Nicolai Rodeyns , director, Naseco, observes that although farmers in western Uganda still believe that the soils are fertile, it is important for them to consider challenges of reduction of soil fertility. This is as a result of soil erosion and other factors and therefore the need to adopt sunn hemp as one of measures to curb soil infertility.
He says he obtained foundation seed of sunn hemp crop from a farmer in Amuru District, in Northern Uganda, who has been growing it and supplying it to other farmers for the same reason.

“Since farm inputs such as fertilisers, and herbicides have proved to be expensive coupled with the taxes imposed on these inputs, it is good to introduce such crops to farmers who will be in position to grow them on their farms and share with fellow farmers,” he said.

About the company
Naseco is mandated to produce Longe10H, which is the major share of their seed business. They have a storage capacity of 300 to 400 tonnes in a particular season.

What the company does is obtain foundation seed from the National Crops Resources Research Institute in Namulonge, and supply it to outgrowers for further multiplication. This is done with close supervision by the company’s agronomists to assure quality.

During harvest, the outgrowers deliver the harvest to the company for processing and packaging.
Marketing is done directly by the farmers by establishing demonstration gardens with 2,000 demos per season.

It is a requirement that when planting seed, the distance observed is four by four metres and no other open pollinated crop is to be grown close to the crop to avoid cross pollination.
The company uses an artificial dryer machine which uses both electricity and biogas generated using the maize cobs as fuel. The seed must dried.
The selling price of all types of seed to farmers is $1 (approximately Shs2600) per kilo and all foundation seed are obtained from Namulonge.