What do sea shells have to do with the price of rice?
A lot in Sierra Leone, where farming business AgriCapital, which has started growing the grain.
"The trouble was that the land was too acidic. It is an issue for much of Africa, which sits on granite, making the soil acidic," Robert McKendrick, a former geologist, and the company's founder and chairman said.
"But there was no way we could financially justify shipping in limestone."
The solution was to turn to sea shells instead, which does the same job. The group set up a plant in Freetown, the Sierra Leone capital, from where it transports crushed shells to apply to the 3,000-acres it is clearing to grow double-cropped rice and ground nuts on.
"The PH is now neutral," Mr McKendrick told Agrimoney.com.
The group in April planted its first 300 acres of rice in April, with harvest set to start next month. And it is expecting a yield of more than 2 tonnes per hectare, more than twice the level African farmers typically achieve.
And as for the price, the group's efforts should actually bring the price down in Sierra Leone, a net importer of rice, by undercutting supplies bought from countries such as Pakistan, which sell at about £450 a tonne – and rising.
"We simply aim to grow it, bag it, put it on the shelf. That will bring the rice price down, which will help Sierra Leone, but still see us making a profit."
And potentially more so, if the double cropping with ground nuts, which Sierra Leoneans mix with cassava in a stew, works too.
"This puts nitrogen into the soil. It's a perfect match," Mr McKendrick said
"It seems to be working like a dream."
So much so, that Mr McKendrick, who came to West Africa some five years ago to seek oil deposits, believes he may have struck rich returns with rice instead.
The group, which started initially with some 700 private investors, and targeting returns of 175% over five years from capital uplift in the value of the land besides income from produce, is considering a capital raise to expand massively its land holdings.
Mr McKendrick has taken options on 30,000 acres of land in Liberia, also a rice importer, besides a further 20,000 acres in Sierra Leone, with the aim of raising the money to develop the sites through a listing on London's Aim market.
"It will end up being a very substantial company, with turnover of more than £50m a year," he said.
"It will probably be among the biggest farming companies in West Africa growing food crops."
There are far bigger concerns in West African agribusiness, of course, such as Sime Darby, which is considering an investment of nearly $2bn in Cameroon plantations, after setting up in Liberia, while Wilmar has bought plantations in Ghana, and Olam International invested in Gabon.
And that's before getting to the array of giants big in Ivory Coast and Ghana cocoa.
But as for a recipe of double-cropping rice and ground nuts for local consumption, with a bit of help from sea shells, that seems to be a niche AgriCapital has all to itself.