Against the grain: Turning rice husks menace into soft and friendly matter

At his factory outside Wang’uru shopping centre in Kenya’s central region, 34-year-old Alex Kabiru is busy emptying sacks of yellowish grain-like material around a metallic circular chimney.

Above, a small, whitish smoke goes up into the air as the materials continue to burn, while a group of young men help him offload more of it around the burner forming a huge heap, which they keep turning using shovels.

These are rice husks, the outermost layer of rice grains, which are removed during milling. They’re light but bulky to store or transport, forcing millers and farmers to discard them on roadsides or through open-air burning.

“The process of disposing of rice by-products, including husks, has been a major headache for both farmers and millers for many decades in this region,” Kabiru tells The EastAfrican.

“The husks take too long to decompose, so dumping them isn’t effective, while burning them openly isn’t friendly to the environment either.”

From this challenge, Kabiru has developed a profitable and environmentally sustainable venture that has created employment for him and six other young men at his biochar production yard.

Biochar is a dark, lightweight, charcoal-like substance resulting from burning organic material such as agricultural waste, paper mill waste, or other biological residues.

The process, called pyrolysis, involves heating the rice husks at high temperatures in the absence of oxygen, resulting in a product that can increase water and nutrient retention, reduce soil acidity, and help retain carbon in the soil.

“We’re turning the rice husk from a useless by-product that was a nuisance to farmers and millers into a viable business and an opportunity to address pressing environmental issues,” Kabiru says.

Having dropped out of a civil engineering course in 2012 due to a lack of university fees, the father of two spent four years tutoring at a local school, but the income was not sufficient to provide for his family, forcing him to quit and turn to agriculture in 2019.

Then, millers would give him the husks free but, with the growing demand, Kabiru now has to purchase them for a dollar for a bag of 35 kilogrammes.

“My main clients are manufacturers of organic fertilisers because they purchase them in bulk. The rest I sell to local farmers and use on my farm,” Kabiru says.

About four kilometres away from Kabiru’s yard, a white truck is blocking the entrance as we arrive at Safi Organics, a small-scale fertiliser production firm in Mwea, which uses agricultural waste to produce organic fertilisers.

The company staff are busy loading the truck with organic planting and topdressing fertilisers that it produces from fortifying biochar, which they source from youth groups in the area.

“The high cost of fertiliser is a significant challenge for most farmers in Africa. We’re changing the narrative by producing fertiliser using locally available resources, specifically tailored to African soil, particularly in Kenya,” says Joyce Kamande, the company’s head of operations.

The company sells 50-kilogramme bags of fertiliser at about $20, which is about 50 percent cheaper than regular chemical fertilisers.

In 2023, the imports of chemical fertiliser in Kenya rose by 62.9 percent to 915,751 tonnes, partly driven by the government’s policy of providing subsidised fertilisers, but scientists believe they lead to acidification and degradation of their soil over time.
“Biochar is very important to the soil.

It improves fertility and health and adds nutrients such as phosphorous, which is highly required by rice to increase its fertility and eventually yield higher yields,” said Prof Paul Kimurto, a lecturer at Egerton University.

The innovations around the utilisation of rice husks and other rice by-products are being championed by Kilimo Trust, a non-profit that focuses on agricultural development in regional trade, nutrition, and food in East Africa, in partnership with Egerton University and the Kenya Agricultural and Livestock Research Organisation (Kalro).

Through its Reduce, Reuse, Recycle Rice Initiative for Climate Smart Agriculture (R4iCSA), supported by the IKEA Foundation, the organisation aims to promote sustainable rice production practices among 10,000 smallholder rice farmers in Kenya and Uganda to mitigate effects of climate change.

“Our primary focus is to make rice production in the region more sustainable by increasing productivity and incomes for farmers and other value chain actors, enhancing the resilience of livelihoods, and reducing and removing greenhouse gases from the atmosphere,” says Anthony Mugambi, Kilimo Trust Kenya team leader, who heads the project.

“Rice production contributes about 10 percent of total greenhouse gas (GHG) emissions from the agricultural sector, mainly because of methane (CH4) emissions from continuously flooded wetland rice fields, so we want to make sure that what comes out of the farm goes back to the farm or is recycled.”

In the country’s western region, we meet 40-year-old Alex Odundo, a machine fabricator in Alendu, Kisumu County, busy welding a hollow metallic cylinder in his workshop, near the Ahero rice irrigation scheme.

He’s racing against time to meet production deadlines for his products, including chaff cutters, grain shellers, water pumps, sisal decorticators, and his eco-friendly cookstoves, which rely on rice husks as biofuel.

“We’re trying to encourage people living in rice-growing areas to use rice husks in our environmentally friendly stove as a source of energy instead of charcoal and firewood in order to protect the environment,” Odundo says.

The cookstove is equipped with a small solar-panel electric fan, which regulates oxygen levels. This fan ensures the rice husks burn cleanly without smoke, reducing indoor air pollution and producing a strong flame.

“With this stove, I not only cook faster for my clients but also use less than half of what I would have spent if I used a charcoal-based stove,” says Jecinta Anyango, who runs a small eatery in the area.

Individual household cookstoves are priced between $30 and $45, depending on their size. Each cookstove comes equipped with a solar panel and a small battery. Odundo has already sold more than 300 stoves.

Due to their low nutrient content, rice straws are unsuitable for use as animal feed. Disposing them of posed significant challenges for farmers, and the most common method to clear a rice field was to burn the rice stalks, resulting in air pollution from the smoke.

But through vermicomposting, a 39-year-old farmer in the West Kano Irrigation Scheme in Kisumu County has adopted an innovative and sustainable way to utilise the rice straws throug the scientific process in which earthworms, primarily red wrigglers, convert the organic waste into manure, rich in high nutritional content.

“I collect the rice straws from local farms because they’re readily available, chop them into smaller pieces, mix them with organic materials like cow dung, and allow them to decompose for 21 days before introducing the red wrigglers,” the farmer, Maurice Lango, tells The EastAfrican.

Vermicast, the final product of vermicomposting, is a nutrient-rich soil enhancer that helps plants grow better and keeps the soil healthy. Vermi juice, a liquid extracted from vermicast, can be used as a quick-acting fertiliser.

From the rice straws, Lango not only generates income but also contributes to climate change mitigation and the promotion of a circular economy.

“Between 2021 and 2022, we produced two tonnes of vermicast, which we used in the rice fields as organic fertiliser, and about 3,000 litres of vermi juice, which we sell to other farmers in the area who use it in place of synthetic fertilisers,” he explains.

He sells a litre of vermi juice for just $0.39 but believes he will make more once the content has been accurately measured and validated.

“What we urgently need is assistance in measuring the content concentration. Once we get that, we can correctly price our product, package and brand it well, and put it on the market,” Lango says.

In Uganda, the organisation is partnering with the Makerere University Agricultural Research Institute Kabanyolo (Muarik), the National Agricultural Research Organisation (Naro), and the National Crops Resources Research Institute (Nacrri) to make rice farming sustainable.

In Mbale, eastern Uganda, Diners Group is now processing previously underutilised rice milling by-products such as broken rice and rice bran into ready-to-consume, nutrient-rich products such as instant rice porridge, instant noodles, and instant rice snacks.

“These by-products were either wasted or sold at low prices, which did not maximise their potential value. The value addition has enabled us to expand our market presence and increase the company’s revenue streams,” says managing director Muhammed Ssekatawa.

Other climate-smart practices being championed by the project include rice legume integration, where market-demanded household legumes such as soybeans are rotated with rice in the field.

This achieves a triple benefit of enhancing household nutrition and income security while also improving soil health through nitrogen fixation.

Other initiatives include alternate wetting and drying (AWD) as opposed to the continuous flooding of paddy fields. This reduces the volumes of greenhouse gases—especially methane—emitted from the rice fields while at the same time reducing water waste.

“Paddy rice production is inherently water-intensive; estimates show that we use between 2,500 and 5,000 litres of water to produce a kilogramme of paddy rice,” says Dr Wilson Oyange, a senior agronomist with Kenya’s Ministry of Agriculture.

“This has brought the need for the exploitation of alternative methods that can significantly reduce water consumption and enhance the sustainability of rice cultivation.”

Rice consumption in East Africa has been steadily rising, driven by changing consumer habits, especially by the growing urban population, but dependence on wetland areas for rice production has left many countries unable to meet their needs.

Data from the Kenya National Bureau of Statistics (KNBS) indicates that annual rice consumption in Kenya is estimated to be over one million metric tonnes, while the production capacity is approximately 230,000 metric tonnes.

In 2023 alone, the country spent $421 million to import 937,098.5 metric tonnes of rice to plug the rice deficit.

“The rice consumption growth rate across Africa has been growing steadily. This growing demand is expected to put pressure on the environment owing to the high demand for water and fertilisers that the crop requires,” Mugambi says.