HOW to feed a growing population with less land and less water is one of the biggest issues facing scientists around the world, according to Victoria's chief agriculture scientist.

Department of Primary Industries chief scientist Graham Mitchell told guests at Grains Innovation Park's 40th birthday celebrations in Horsham last week that the "arithmetic causes sleepless nights".

"We need to double the amount of food by 2050 with a quarter less land - and the gorilla in the room is overpopulation," Dr Mitchell said.

He said demand for food was growing at 3-4 per cent per year, while agriculture productivity was only growing at 1-2 per cent each year.

To get an idea of how the next 50 years of agriculture would unfold, he said it was worth looking back to the past 50.

During this time there had been great leaps in molecular biology.

"If there's anyone in life sciences who does not have a knowledge of genetics, then they're not on the same page," Dr Mitchell said.

"People simply need to have a working knowledge of molecular genetics."

He said there had also been vast advances in communication, robotics and knowledge sharing.

"Agriculture has been around for more than 12,000 years, or 600 generations," he said. "That has been characterised by long periods of stability - punctuated by rapid change."

Dr Mitchell said the past 50 years of Australian agriculture had been relatively stable, but a tsunami of instability and change was predicted.

"You ask people what matters the most to them and they will say 'an assured supply of safe, affordable, nutritious food'," Dr Mitchell said.

He said the use of researchers and scientists was critical, and a focus on the application of science at the expense of new research was dangerous.

"If anyone says we should go light on the science and technology and apply what we know now, them I remind them of malaria and smallpox," Dr Mitchell said.

"In theory DDT is a tool we can apply to kill mosquitoes and wipe out malaria, but we still have malaria in spades.

"We have a smallpox vaccine we can apply, but we made a decision to continue with the research.

"We don't have smallpox, but we do have malaria."