November 18, 2021

What is the single stem system & how does it affect coffee production?


While increased yields are always beneficial for coffee farmers, it’s not a case of growth by any means necessary – farmers also want to increase quality and minimise the cost of production as much as possible. 

Over the centuries, many innovative ideas have been rolled out in order to achieve this extra productivity, all with varying degrees of success. One of the more recent and most successful of these innovations is the single stem system, also known as the one tree or one stem system. 

This approach aims to maximise the potential of the tree, minimise nutrient competition, reduce labour, and decrease incidence of pests and diseases. Ultimately, this can reduce the cost of production per tree significantly. 

I spoke with three experienced African coffee producers to get a better grasp of this technique and its benefits. Read on to find out what they said.

You may also like our article on five useful tools that can make a difference to coffee producers.

african landscape

Why is there a need for a new system?

When it comes to coffee production, quantity and quality are intertwined. They are the two most important factors for farmers, as they dictate how much money they receive for each harvest.

Traditionally, producers believed that the more fruit-bearing stems a tree had, the higher its yield would be. While this is partly true, more stems means more expenses, for a variety of reasons.

In the past, labour was cheaper and more readily available. The effects of climate change were also not necessarily being felt to the extent that they are now, meaning that farmers could depend on reliable weather patterns.

However, with erratic weather patterns growing in frequency, dwindling labour availability, and a host of other factors, the cost of coffee production has increased significantly. This means maintaining multiple-stemmed trees is even more costly than it was in the past.

James Gicaga is a farmer from Nyeri County in central Kenya. He says that his father, who was also a coffee farmer, was unable to sustain his business because the efforts did not justify the returns. 

“My father used to have as many as five stems for a single coffee bush,” he says. “The amount of attention needed to maintain these trees is just crazy. Eventually, he decided to retire early.”

James, however, believes that he will be more successful, as he is able to comfortably manage his trees using the single stem system.

coffee leaf rust

What is the single stem system & what are its benefits?

The single stem system is exactly what it sounds like: a single stem alternative to the multi-stemmed tree system that James talks about his father using.

As the name suggests, the single stem system is where farmers prune away any emerging smaller stems (also known as “suckers”) to minimise competition for nutrients. This helps to improve yield and quality, while also making the plant easier to maintain.

The reduced cost of production that comes with the single stem system is a welcome relief for many farmers. However, there are other benefits, too. One example, James says, is the reduced need for agricultural inputs such as fertiliser and pesticides.

“I believe that we have been spraying too many chemicals in the air in the name of better quality,” he explains. “This system of single stems has reduced the amount we used to spray by almost half. This is good news for the environment.”

Like James, Moses Mwangi also farms coffee in Nyeri County. He, too, has embraced the single stem system, and tells me he is thriving because of it. He says he’s now able to harvest at least 25kg of cherries per tree. 

“I am never going back to the old system,” he tells me. “The best I could manage was around 10kg per tree, and that was the result of too much effort. Now, life is much simpler on the farm.”

He says his success is largely attributed to his reduced production costs. Like with James and his sprays, Moses has saved money by reducing his manure and fertiliser use. That’s not all, though.

He says: “Pests and diseases thrive in dark and humid places, but with single stems, pruning and opening up the tree is easy. You expose the pests to rain, sun, and predators.” 

James adds: “Two people can now prune a whole farm and completely spray in one day. This was not even remotely possible with multiple stems.”

Another benefit of the single stem system is the fact that it is suited to production at all altitudes and in all regions. The fundamental advantage remains unchanged, too. The trees achieve maximum productivity thanks to the strong framework of their primary branches.

John Wanjohi is a veteran coffee producer from Embu County, also in central Kenya. He believes that the single stem system is a method of achieving more sustainability in the coffee production sector.

“I always believed that the more stems you have, the higher your production,” he explains. “But this is accompanied by high costs because of labour, sprays, fertilisers, manure… for an old guy like me, this is not sustainable.”

In John’s case, the single stem system could not have come at a better time; he says it has been a “life saver”.

single stem coffee tree

Establishing a single stem system 

There are various ways of establishing a single tree system on coffee farms, but one of the more popular methods is “top working”.

In Kenya, this vegetative propagation technique is commonly used on farms that grow traditional varieties like SL28 and SL34. These older trees are converted into modern varieties such as Batian and Ruiru without interfering with the current cropping seasons. 

Six-month old Ruiru or Batian scions are grafted onto healthy SL variety suckers. After the graft has healed and the stem has strengthened, it is allowed to grow to a desired height and then capped at the top, leaving behind just two primary branches. 

After the first successful cropping and harvest, the old SL stem (or stems) is pruned through a method known as stumping. This leaves the new, single stem behind, ready to produce coffee.

After the subsequent rainy season, new shoots (suckers) will begin sprouting at the bottom of the tree. These are pruned to allow just the one main stem to continue fruiting. If ever the tree needs to be replaced, a new shoot will be trained and allowed to grow. 

Moses says: “Right now I have 275 trees, mainly of the traditional varieties. I have already started the process of top working to convert them into Ruiru, and 190 trees are already grafted. I hope to have a Ruiru plantation in the next two years.”

african sunset

The Kenyan coffee farmers in this article all believe that the one tree system is the future of coffee production. In some cases, it has completely reversed the fortunes of struggling producers, giving their aging trees a new lease on life.

As the interviewees suggest, the system does not simply increase yields, but reduces the cost of production significantly as well. In addition, because these trees are less susceptible to pests and diseases, fewer agricultural inputs are needed.

“I am going to lease an abandoned farm in the coming season and I will exclusively have single stem Ruiru bushes,” Moses says. “I hope to have at least 40kg per tree in the main season.

“For me, this single stem system is the only way forward.”

Enjoyed this? Then read our article on the benefits & challenges of agroforestry for coffee farming.

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