By Francis Ndungu

Agronomist and farmer Alex Maina has boosted his French bean production by abandoning fertilisers that were harming his soils  and perfecting a home-made spray that has lifted his harvests by 47%.

“I was using inorganic fertilizers from the agrovets until 2019, but the repeated usage was reducing my yields. The pods were getting smaller, my production had fallen to less than 1000 kg from ½ acre of French beans, and the fertilizers were expensive,” he said.

In 2020, he tried using a home-made spray after reading an article recommending stinging nettles as fertilisers. “I then realised I could add extra ingredients to make it even better for my crops,” said Alex. “My French beans production increased to 600-1000 kg per pick, where I was getting two picks per week during the picking season.”

After five years of perfecting his spray, which beans absorb easily because of the large surface of their broad, flat leaves, his recipe today is made up as:

• 1 kg stinging nettles
  
• 1 kg tithonia
  
• 1 kg comfrey
  
• 1 kg ash
  
• ½ bucket cow slurry.

It gives his crops extra potassium, nitrogen, calcium, boron and zinc which encourages extra flowering, healthy pods and accelerated growth.

“The faster growth helps in getting better market prices too,” said Alex, who also irrigates his farme to widen his harvest seasons. “Prices can fall as low as Sh50 per kilo when farmers are all harvesting at the same time.”

The spray has also made a big difference to pests. “The smell of it repels pests such as thrips, aphids and white flies, which had been a problem on my crops,” he said. 

Spraying every second week during the growing season and weekly during harvesting, Alex said he had benefited from the absence of chemical residues, which means he can harvest any time the crop is fruiting.

“I used to have limits before around pre-harvest intervals and problems, too, with some of my crops rejected because of residues, but the organic spray doesn’t have any safety intervals or residue risks.”

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To make the spray, he uses a 20-liter container, chopping up the fresh tithonia, stinging nettles and comfrey, mixing the ingredients together and leaving them to ferment. 

He has to cover the container carefully and runs a tube off it to another container filled with cold water. This releases the methane gas made by the fermentation, which could, otherwise, burst the container.

He ferments the mixture for 28 days and then sprays in the early morning or evenings as a dilute mixture of one part fertiliser for 20 parts water. “This stops it scorching the plants’ leaves and evaporating in the heat of the day before it is absorbed,” he said.

After spraying the leaves and whole plant for 2 – 3 weeks, “the results are amazing: they are green, healthy and very thick, the pods come in long and fine, and the aphid infestations are just stopped.”