Standing inside the massive rice farm in Amuru district, 47km from Gulu Town in Uganda, Dominic Kimara reminds one of the proverbial needle in a haystack.
Well, unlike the needle, which would certainly be harder to find, the taller Kimara is easy to pick out.
The farm stretches as far as the eyes can see, covered in the distinctive brown colour of a rice crop that is ready for harvest.
“We farm on 5,000 acres using upland technology, which means we don’t grow the crops on paddies. We rely on the rains,” says Kimara, the farm manager at Omer Farming Company, which runs the farm.
But that is not the only technology that they have adopted, which caught the eyes of Seeds of Gold team. The farm does not use a single granule of fertiliser yet they harvest up to 3.5 metric tonnes of rice per acre.
“We do not plough the field, and we do not use fertilisers. We grow sunn hemp as green manure and sometimes we rotate it with pearl millet,” says Kimara.
When the two crops are 50 per cent flowering, they are rolled flat on the ground and left to decompose, thereby fixing sufficient nitrogen into the soil to provide crucial soil nutrients for upland rice to flourish.
Sunn hemp, which is scientifically known as Crotalaria juncea is a leguminous fodder crop originally from Asia, where it is sometimes grown for fibre to make ropes, fishing nets, paper, canvas, carpets, among other things.
But being a strong nitrogen-fixer, scientists recommend it for use as green manure.
Studies have shown that in two to three months, sunn hemp can produce up to 120 pounds of nitrogen per acre, and suppress 90 per cent of common weeds.
The crop is an excellent soil builder and produces a lot of biomass – over 20 per cent greater than crimson clover and hairy vetch, according to studies.
Kimara says sunn hemp is planted almost two months before the rice is grown. When the crop starts flowering, it is rolled flat on the ground using tractors and left to decompose.
“Once it decomposes, the soil is left with no weeds, but with a lot of nitrogen nutrients and biomass. So when we finally plant rice, there is absolutely no need of applying any nitrogen fertiliser.”
The company has become one of the biggest producers of organic upland rice in Uganda, and so far, smallholders in Amuru are following suit.
“I never knew that one could grow rice without paddies,” says Regina Kisembo, a smallholder farmer from Luwila village in Amuru district.
“Nearly all farmers in this area are now growing the upland rice for food, and we sell the surplus to Omer and other companies.”
Kimara notes that 1,700 farmers in the area have adopted the new farming technique, and are growing upland rice under contractual agreements with the company and other rice milling companies.
A recent study by the University of Florida in US shows sunn hemp uses different modes of action to suppress plant parasitic nematodes, making it an efficient cover crop for nematode management.
“Sunn hemp is not only a poor host or non-host to many plant-parasitic nematodes, but it has been shown to produce allelopathic (toxic) compounds against several key nematode pests,” reads part of the study.
The researchers further found out that sunn hemp also can enhance natural enemies of plant-parasitic nematodes, such as fungi that trap nematodes or feed on their eggs, thereby making it the best cover crop for different types of crops.
“The beauty of this plant is that it is drought-tolerant and grows very well in tropical climatic conditions,” says James Ekebu, a research assistant at Uganda’s National Agriculture Research Organisation (NARO).
Dominic Kimara, the farm manager, at Omer Rice Company in Uganda inside a sunn hemp field before the crop is flattened and rice planted. The crop is an excellent soil builder and produces a lot of biomass.
Photo credit: Isaiah Esipisu | Nation Media Group
He adds that the plant can handle moderately low soil pH, making it an excellent choice for acidic soils.
Until 2016, the Omer was growing maize as the main crop. But following research that led to the release of new improved high-yielding upland rice varieties, the company switched from maize after comparing the yields against the prevailing climatic conditions in North Western Uganda.
They farm a variety known as ‘Namulonge Mchele (NamChe)’, the latest high-yielding upland rice type developed through a collaboration between NARO and the Alliance for a Green Revolution in Africa (Agra).
Edible nitrogen-fixing plants
Dr Jimmy Lamo, who led the team during the development of NamChe, says it yields 3.5 tonnes for the late maturing varieties and two tonnes for the early maturing ones.
“The yields can be even much better when using a cost-effective no-till system and you do not incur fertiliser costs,” says Dr Lamo.
Gulu has climatic conditions relative to western Kenya, but with slightly lower anual temperatures. The region receives averagely 1,800mm of rainfall per year, while Kenya’s receives a maximum of 1,940mm per year.
Sunn hemp works very well for upland rice than maize. So Kenyans, especially in western who are eager to farm upland rice, can easily adopt use of sunn hemp.
John Macharia, the country manager at Agra, says though sunn hemp is not widely used in Kenya, Kenya Agricultural and Livestock Research Organisation in collaboration with Agra has introduced various leguminous crops for nitrogen-fixation for maize farmers in western.
“It all depends on the soil type and soil profile. Sunn hemp is a very good nitrogen-fixing plant but in places like western Kenya (Kakamega, Vihiga and Nandi counties), we have started by scaling up the use of edible nitrogen-fixing plants (pulses) and vegetables, and also with controlled use of balanced fertilisers.”
1. Sunn hemp is particularly good because it can as well be used as fodder, thereby bringing in the link of human/animal interaction,says John Macharia, the country manager at Agra.
2. Sunn hemp grows well off season (warm season) because it is drought-tolerant. When it rains, then it can be ploughed back into the soil to form green manure.
3. Tractors are used for planting and weeding, though sunn hemp controls most of the weeds. It suppresses them. For harvesting, combine harvesters are used to pick and process the rise.
