It’s hard for an African engineer to explain why he’s joining the labourers in the dirt.

If you’ve been lucky enough to be the one chosen among your siblings to go to school, and smart enough to win a university scholarship, and hard-working enough to turn that into a prestigious career, then why would you go back and work as a labourer?

Musenga Silwawa was calling me from back home in Zambia. He was standing on a farmer’s porch, looking at a small-scale corn field with dirt under his fingernails. He’d been working there for 2 weeks.

I could imagine his signature smile, big and wide with friendly eyes, as he told me: “You know Sal, I’ve learned exactly how to improve my applicator, and I learned that farmers don’t buy it for fertiliser efficiency, but to avoid pilfering. It’s really good. This farmer won’t let me leave unless I sell him my prototype! He’s insisting. He even offered me more money. But let me tell you Sal, I don’t think working on more farms is going to be effective to grow my sales.”

I wasn’t sure if this was Zambian humour. In either case, Musenga went on to pre-sell over 25,000 units.

Musenga Silwawa has never been one to shy away from the field, but still, he’d never worked in his users’ shoes.

Usability testing — especially in context like Musenga was doing — is deeply undervalued by people who haven’t tried it. Like most forms of deep customer contact, it takes doing it to have those aha moments, to get some insight where you now know what to focus on. It’s discovering those unknown unknowns that get your business on the right track but lectures and books just don’t convince.

Musenga had sat through a few weeks of startup and design training. Well-built with a clean-shaven head, he’d sat quietly at the back of the classes. I noticed he never smiled. It was a little intimidating.

At first, I thought, this stuff isn’t right for him. It was my first time teaching in Sub-Saharan Africa, and it was clear that a lot of our Anglo-Saxon ways weren’t relevant here.

So I’d talk to him one-on-one, and as I learned about his product, a farm implement designed to double the efficiency of applying fertilizer with seeds. Fertilizer in the backpack attached to a hand-held tube system that looks like a walking stick. Each time you plant your walking stick in the ground, and it buried a seed surrounded in fertiliser at the perfect depth.

As an engineer, Musenga was focused on the mechanical systems and the efficiency of fertilizer. As an academic, he was managing the relationships between two universities for his project. He wasn’t aware of farmers’ buying mentalities, and he didn’t place much weight on the needs of the labourer, his end user.

It wasn’t a knowledge problem — he had been taught about “understanding customers” and “user experience” already — it was an action problem.

This wasn’t an education challenge, it was a mentoring challenge.

Why mentoring matters

Successfully taking a business to market requires not just specialised knowledge, but the application of that knowledge.

For a given startup, that knowledge exists only in a few minds, like yours, and the time you’ll have together is limited and precious.

Mentoring skill is an extremely powerful multiplier in this equation.

This was an excerpt from my book Mentor Impact. You can download it free for the next few days at

If you’d like to meet Musenga, join us at Source Summit Humanitech in London on Sept 12th. And if you’d like to learn about more of the Africa Prize alumni, I wrote about a few of them here: