And to make it even simpler, farmers will soon be able to answer those questions using their mobile phones.

When the program launches in the Philippines in a few weeks, a farmer can call a toll-free number and hear a recording in his or her language that will ask questions about the size of the field, how much rice it produced last season, sources of natural fertilizers such as rice straw or sediment from river flooding, and so on.

The farmer answers the questions using the keypad on their mobile phones. A computer does the calculations and sends a text message with the amount and type of fertilizer to apply.

Farmers apply fertilizer to an experimental rice field.

Making money, protecting the environment

Buresh says the impact on farmers' incomes could be substantial.

"Just a back-of-the-envelope calculation shows that in the Philippines, if we in a year can be reaching just five thousand farmers and their fields can be increasing the yield by half a ton per hectare, we could be looking at profitabilities for those farmers in the range of half a million dollars."

In addition to the financial benefits, it could also help farmers reduce fertilizer pollution.

"In the Philippines and all over Asia, fertilizer has been overused and misused because no one explains to them how much they need or how to use it," says Danielle Nierenberg, a senior researcher with the environmental research organization the Worldwatch Institute.