Dr Dennis Beesigamukama, a Postdoctoral Fellow in Insect Frass Fertilisers and Soil Health and the lead research scientist on the project at Icipe shows maize grown using BSF-composted organic fertilizer. Photo Credit: icipe

Icipe scientists seek super organic fertiliser from insects

Murimi Gitari
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[rt_dropcap_style dropcap_letter=”A” dropcap_content=”BOUT a third of arable land is severely degraded, according to the Food and Agriculture Authority (FAO), costing the world US$400 billion in agricultural production each year.”]

Soil degradation reduces the quality and quantity of crops produced as the capacity to support animals and plants by the same soil is diminished. This causes the soil to lose the chemical and biological qualities that sustain the millions of organisms living within it.

Over the past few years, fertiliser prices have skyrocketed due to the Russia-Ukraine war, adding the burden on farmers already struggling with the effects of drought and other challenges associated with food production At the Nairobi-based International Center of Insect Physiology and Ecology (Icipe) scientists have been burning the midnight oil trying to develop alternatives to taming this pandemic of the soil through the use of insect composted organic fertilisers.

The research focuses on refining and diversifying frass fertiliser production technologies and understanding the impacts of insect-composted organic fertilisers on soil health and crop productivity in different agroecological zones. Dr Dennis Beesigamukama, a Postdoctoral Fellow in Insect Frass Fertilisers and Soil Health and the lead research scientist on the project at Icipe, says use of organic fertilisers have the potential to transform food systems in Africa.

“Organic fertiliser is the one of the solutions of addressing fertiliser crisis and soil degradation. In Africa, about 65 percent of the soil are highly degraded and can no longer support crop production with 25 percent of the soils having the challenges of soil acidity caused by aluminium toxicity and nine percent lack phosphorous,” says Dr Beesigamukama.

“Here at the centre, we use saprophytic insects which feed on decomposing matter as bio converters of organic waste into high quality and cost-effective fertilisers.” All insects that feed on organic matter can be used for production of organic fetiliser.

But the centre is currently focusing on more than 10 insect species, including the Black Soldier Fly (BSF), mealworms, crickets, beetles, desert locusts, silkworms and grasshoppers, for the production of organic fertiliser, animal feed and food.

The BSF is preferred by the researchers because of its efficiency in biodegradation. Its voracious appetite offers the opportunity to recycle bio-waste into organic, high-quality fertiliser, while also contributing to waste management and animal feed.

The BSF has the ability to convert one ton of food waste into 250 kg of fresh larvae within 12 days. This process can potentially be two to 10 times faster than composting, depending on factors such as temperature, aeration method, and moisture content.

With BSF, one needs a maximum of five weeks to get a mature and stable organic fertiliser compared to a period of between two to six months for the ordinary composting methods. “A plant requires between 18 and 21 nutrients to grow and produce enough yields but the synthetic fertilisers like NPK can only supply three with other supplying four.

Organic fertilisers can supply all these nutrients and this is why we look at them to rebuild the soil, reduce the acidity in soils and rejuvenate organic matter and beneficial microbes which are key in improving soil fertility.

They have additional benefits like improving soil moisture storage that is key in adapting cropping systems to the shocks of climate change, which synthetics may not do. So that’s why we are looking at organic fertilisers as inputs that could play a critical role in enhancing the productivity of the food systems, especially for smallerholder farmers,” says Dr Beesigamukama.

“In conversion of organic waste into organic fertiliser, we have the insects who act as ‘main factories’ as they break down the waste during their growth age as they feed. As they pass the waste through their digestive system the waste they release is now what becomes as organic fertiliser. This process takes place in the wild and what Icipe has done is to make it captive or domesticate it by establishing insect rearing systems.”

The insects reared in these systems lay eggs in the any kind of waste, including animal manure, waste from the markets, food waste, and industrial waste that is decomposable.

The larvae hatch after four days and then starts feeding for a period of between nine and 16 days depending on the conditions. As they feed, they break down the waste.

After the 16 days, the scientists then harvest the insects through sieving to separate the larvae from the waste to get what is known as frass or residue. The frass is then taken through a post-treatment process to convert it into a mature and stable fertiliser.

This process of treatment takes only four weeks from the period of larvae harvesting, giving a period of only five weeks to get the mature fertiliser. After separation the frass is taken through a composting process. Beneficial microbes in the waste and digestive enzymes help to speed up the waste degradation.

The frass or organic fertiliser can be used in the production of any crop. Dr Beesigamukama their research findings show excellent performance of the frass fertilser in boosting crop yields. For example, in maize they found that the frass fertiliser could increase grain yield by between 6.0-27 percent compared to 7.0 percent for the conventional organic fertilizer and NPK. For beans it was up to 12 percent higher yield compared to synthetic fertilizer and 58 percent yield higher compared to unfertilised soil. “Another benefit of the frass fertiliser is the profitability of crop production.

We have found that this fertiliser can increase the profits from crop production by between 10-154 percent. It can also increase the gross margins of farmers by 35 percent and the return on investment can increase by between 5.0 percent and 156 percent. From what we found, if farmers can produce this fertilser and use it on their own farms, they would make profits that are way higher than if they bought it.” Frass fertiliser is also less expensive than synthetic fertilisers. It costs US$854 per hectare every season to fertilise with synthetics, but only US$390 per season using frass fertiliser over the same area.

Furthermore, frass fertiliser has been found to be effective in suppressing devastating crop pests such as potato cyst nematodes, root knot nematode, and cabbage and onion root maggots, as well as the tomato bacterial wilt disease. “We do provide free hands-on training here at Icipe to anyone interested in learning about the production of organic fertilizers or anything to do with insects,” Dr Beesigamukama says

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