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Farmers In Eastern Uganda Using Rice Husks To Fertilise Soils

by Harvest Money Editor
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Continued decline in soil fertility across the country, coupled with the high cost of fertilisers that can rejuvenate the soils, is threatening food production and security across the country.

This decline has been attributed to poor farming practices like continuous cultivation with absence of fertility management, bush burning as a means of land clearing, encroachment of forests and wetlands, in addition to the growing population, among others.

According to a report titled Assessment of Fertilizer Distribution Systems and Opportunities for Developing Fertilizer Blends in Uganda, that was carried out by AFAP and IFDC, and funded by the Alliance for A green Revolution in Africa (AGRA), the eastern region was identified as a region with low levels of fertility due to over cultivation of land apart from those areas closer to Mt. Elgon.

Nonetheless, though Eastern Uganda has been singled out, as one with low soil fertility, a Senior Soil Scientist from the National Agriculture Research Laboratories Kawanda, Dr Crammer Kaizzi Kayuki, affirms that all soils in Uganda have lost fertility.

He adds that these mainly lack nitrogen and phosphorus, which are key nutrients in the soil, providing for proper plant growth.

He attributes this decline to nutrient mining through crop harvests, and which are never replaced, and loss of organic matter through soil erosion and runoff.

For eastern Uganda, especially eastern highlands around Mt Elgon, Kayuki attributes the fertility loss to the abandonment of traditional soil conservation practices like mulching, use of trenches, terracing for those farming on the slopes, trees planting to provide as wind brakes, in addition to increasing population, that has forced farmers to farm continuously without allowing the soils to fallow or rest.

What could be the solution?

To help farmers adjust to the reality, organisation like Kilimo Trust, have resorted to working with farmer groups and private sector to promote the use of rice husks which when carbonized (burnt under low oxygen supply), form biochar, which is used as soil conditioner.

This could improve the soil structure, allowing for proper aeration and microbial activities, but could also be enriched with nutrients, mainly nitrogen and phosphorus from either an organic or inorganic source.

Anthony Mugambi, the project team leader at Kilimo Trust, explained that rice husks are one of the by-products from rice, they are promoting to encourage sustainable rice production.

He said this is being carried out through the Reduce-Reuse-Recycle Rice Initiative for Climate Smart Agriculture initiative (R4iCSA), with support from the Netherlands based IKEA foundation.

Why the solution?

Mugambi explained that the focus on the by-products, including others like rice straw, is in the context of climate change. 

“We want to ensure that whatever comes from the farm is taken back or recycled. For example, rice straws can be composted and used as manure within the farms while the husks can be carbonized, to become soil enhancers,” he said.

Mugambi, who is also an agronomist adds that biochar from rice husks is good for soil modification and good as carbon sink. 

He further explains that greenhouse gases are produced in the rice value chain, especially during the process of flooding for rice produced in wetlands, and also from fertilisers like urea, which evaporates into the atmosphere, contributing to a fraction of greenhouse gases, which are interfering with weather patterns.

“We are trying to reduce all that from rice production systems, and we want to recycle by-products to promote sustainable rice production practices, and also teach farmers how to effectively manage water in rice fields, but also conserve it for future use,” Mugambi added.

With husk use embraced as an alternative fuel source, there will be reduction in use of wood fuel especially in schools, at the same time producing biochar which is a fertiliser, he added.

Mugambi said, in its pilot phase, the project is already working with some farmers in Eastern Uganda, and agri-preneurs such as Andrew Ebong from Bongomin Group Ltd, who is engaged in commercial rice farming, and now produces biochar for both home use and for sale. Ebong supplies this product, biochar, to coffee farming organisations, banana farmers, vegetable farmers among others.

How the business idea was developed

Ebong, who makes biochar from his processing plant at Busoba, Mbale district, says he put the idea to reality after a visit to a friend working with the National Union of Coffee and Agribusiness Enterprises (NUCAFE), where he stumbled on the product for which he was informed that they were importing biochar from China, for their coffee plantations.

Ebong, who is a rice production expert, then requested for an opportunity from NUCAFE to produce the same product using rice husks.

He explained further that as soon as he was given a green light, he organised for the making of the first carbonizer or an equipment used to burn the rice husks into biochar, though this did not work well, with the second being fair, but the third working perfectly well.

“For the carboniser to work well, it has to reduce time taken to burn the husks into biochar and controls amount of smoke,” Ebong explained.

From the first supply in January 2019, he still supplies biochar to coffee farming organisations, individual farmers, vegetable urban farmers among others to date.

Benefits of biochar to the plant and soil

Andrew Ebong, an agri-preneurs, from Bongomin Group Ltd Ebong explains that biochar retains the water in the soil for longer time, also enhances microbial activities such as organic matter decomposition, humus formation, nutrient cycling, aggregate formation and stabilisation, which improves the soil structure in the long-run.

When applied in the garden, biochar reduces the acidity of the soil and acts as a carbon sink.

“For example, if you planted a coffee tree with biochar, it supports the plant to remove carbon from the atmosphere and then fixes it in the soil in addition to mobilizing nutrients towards the root zone,” he says.

Anthony Mugambi, the project team leader, displays the rice husks before they are processed into biochar. Filed by Prossy Nandudu

Sources of materials for biochar making

For one to get quality biochar from rice, it has to come from a multi-stage milling machine.  

Pande Anthony, a production manager at Diners Group Ltd, a rice processing company, says a multi-stage mill is composed of a feeder, from where rice moves to the blower to remove chaff, then to the destoner which eliminates stones, then to the huller plucking out the husk to produce brown rice, to the paddy separator which returns husked rice for dehusking.

Thereafter, the rice goes to the whitener or polisher that takes off the bran to give rice the white color, before eventually sending it to the colour sorter and grader for sorting and later packaging.

“Husks coming from a machine that has all the above stages reduces chances of getting rice bran into the husks meant for the production of biochar,” Pande explains.

Tips for production of biochar from rice husks

To get quality biochar, ensure that the husks have no bran, as bran has oil that speeds up the burning process, leading to quick formation of ash.

When burning biochar, first fix dry banana leaves or hay in the base of a prostrate carboniser, then light it and quickly turn it over the fire to an erect position, then add rice husks in bits, making sure that the fire does not burn-out.

Continue adding to the desired levels and keep monitoring to make sure that there is continuous burning but also that it does not burn to ashes.

When the carbonisation process is completed, take off the carboniser, remove the left-over material used to light the carboniser, then put out the fire in the biochar using adequate water and allow it to cool overnight.

The end product will be biochar which can be utilised in the vegetable garden, coffee or banana plantation as a soil conditioner, says Khamali George, who works with Bongomin Group Ltd.

Farmer testimony

Catherine John Mumo, a vegetable farmer, says biochar can be used by in urban and peri-urban areas. It can be used in both multi-storey and other vegetable gardens.

For better results, one has to take one unit (one wheelbarrow) of well decomposed farm-yard manure, one unit of biochar, plus one unit of topsoil, mix them thoroughly then utilise in the garden, she explains.

Mumo adds that they are applying it in sunken beds that have kales, amaranth and spring onions, among others, and in the multi-storey gardens which has herbs including spices like coriander.

“When you look at the coriander, despite the fact that there has been drought and intense heat, it is still green and strong. This means that the ability of biochar to retain water for the plant is well seen here, yet it also has the ability to attract beneficial micro-organisms closer to the root zone, and that is why the plant is doing well,” she adds.

In banana and coffee plantations, Khamali says they teach farmers how to apply the product to their gardens, for those who cannot, they pay them an extra fee for the application of biochar in their plantations.

Stake holders share their views

Dr Lawrance Owere,  director of research at Buginyanya Zonal Agriculture Research and Development Institute (BUGIZARDI)

We have tried making biochar from other materials such as maize cobs and it works. We are now going to into rice husks, so that instead of just burning them, these can be burnt under low oxygen to make biochar, which can be returned to the soil.

Biochar supports mainly biological and physical activities in the soil, but not the chemical bit, so we can enrich it with the required nutrients before applying into the field. However, the application can only be done effectively if we have information on what is lacking in the soils, through a functioning soil testing laboratory.

Deus Nuwagaba, farmer from NUCAFE

Biochar reduces acidity in the soil, making nutrients available for the crop. We are using it as part of our Climate Smart Agriculture practices because it prevents water loss and also acts as a store for the soil nutrients.

We used to import the product from China but after learning that we have Ugandan entrepreneurs who can offer the same, we decided to support them, that is why we are now sourcing biochar locally from local investors like Andrew Ebong.

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