Last year I had an interesting chat with irrigation specialists in Zimbabwe. Two irrigation specialists, however, had the most fun and interesting stories to tell.
I had given them the task to figure out how best and to cost-effectively put 1 hectare under irrigation for one farmer.
Now, in Zimbabwe the standard irrigation set-up for 1 hectare is designed as follows: tank on a tank stand with water coming from a solar-powered borehole via pipe and to the field using drip irrigation.
One guy said there must be a 10 000 litre tank.
The other guy said a 10 000 litre tank is not necessary. I asked how so?
So he did some math with me. He said something like, “Say you have 1 hectare. What’s the plant population?”
“50 000,” I said.
Then he said, “Right, and how many litres of water does each plant need per day.”
“One litre,” I said.
Then he said, “And your tank is 10 000 litres. So how many plants can you water using 10 000 litres?”
I then laughed.
Then he said, “I have come to realise that you don’t really need a tank. The pump is usually working most of the time. Most of the work is actually done by the pump. People who are putting tanks are just adding an unnecessary expense.”
I had a good laugh.
But looking back as I write this, I figure that people put tanks as a water reserve for cloudy times when there will be not much sunlight to produce solar energy.
If the sunlight is there, the tank may be unnecessary for sure.
It was an interesting way of looking at things.
I then asked him, “What about the pressure? When the customer is using drip irrigation it has to be at the right pressure.”
He replied saying, “You can use a pressure regulator.”
One of the things we will do in our operations when we start massively rolling out irrigation systems is to require irrigation specialists to justify their designs.
Yeah, apart from the fact that I don’t want us to be sold things that we don’t need, the design must be justified and must win on merit, and not just cost or the wow factor or “everybody is doing it that way”.