At the current rate of consumption, mankind will quickly consume the Earth’s limited resources, sustainable agriculture expert Fred Kirschenmann said Tuesday afternoon.

Kirschenmann spoke about the future of food production and energy use before an audience of about 30 at a Master’s Tea in Saybrook College. Without new methods of farming, he said, the world’s food supply could become increasingly unstable.

Kirschenmann, the president of a 3,500-acre certified organic farm in Windsor, N.D., began the Tea by mentioning two books that he said have had a profound influence on his views about energy use in agriculture: “The End of the Long Summer,” by environmental journalist Dianne Dumanoski, and “Rising Powers, Shrinking Planet,” by Five Colleges professor Michael Klare.

“What the literature demonstrates is that our total energy consumption has been incredibly liberal,” Kirschenmann noted. “We are going to see significant changes in the way we involve ourselves with food if we continue to take out the earth’s limited resources at this unsustainable rate.”

Kirschenmann added that reduced biodiversity and dependence on fossil fuels are reasons to be worried about the present state of the food system. Growing fewer types of plants increases the risk of one disease or pest wiping out an entire crop, he said.

To reduce risk in the food system, farmers should adopt rotational grazing systems where energy input is comparatively low, and governments should reduce farm subsidies and implement banking policies that would allow farmers to explore a wide range of alternative growing techniques, such as pesticide-free farming.

Everyone should take on the mantle of being “food citizens,” said Kirschenmann, who has chaired the administrative council for the Department of Agriculture’s North Central Region Sustainable Agriculture Research and Education (SARE) program.

“Envisioning a better future leads to more community engagement so that we can own these problems together,” he noted.

Four people at the Tea said they enjoyed the discussion. Patrick Cournoyer GRD ’12, who is researching plant cell biology, said he found the discussion inspirational but not ideological.

“I really appreciated how Kirschenmann emphasized the roles of both the public and private sectors in dealing with these problems,” he said. “Public policy needs to preempt us from having a very rude awakening somewhere down the road, but the food industry needs to be part of the solution too.”

Peter Beck ’12 — who has visited Kirschenmann’s farm — said he enjoyed how Kirschenmann focused on what he believed were “real” answers to the difficulties of sustainable farming.

“The talk was so refreshing to me because it was a very practical and pragmatic conversation,” he said.

The Yale Sustainable Food Project was a co-sponsor of the event.