Mr Benn said he would take the decision on dealing with TB in cattle
Environment Secretary Hilary Benn has been heckled by farmers after he suggested culling badgers may not be the answer to preventing TB in cattle.
Mr Benn was told to "stop waffling" as he pledged to take a decision based on science, its impact and practicality.
And he was booed as he said he would also have to take into account public acceptability.
Tory leader David Cameron addressed the NFU's 100th conference as well, and warned of future global food shortages.
National Farmers' Union President Peter Kendall urged Mr Benn to make the "right decision" on culling badgers and to show political leadership in explaining to the public the "absolutely devastating" effect of the disease.
He urged Mr Benn not to adopt a "nimtoo" approach - "not in my term of office".
Mr Benn said the call would be made "on my watch", based on the science, impact of proposed measures, the practicalities and its "public acceptability".
To boos from the audience he said: "Many of you don't think that's a factor governments should take into account but I have to take it into account alongside the other three tests."
The NFU says about 2,500 cattle a year get bovine tuberculosis and some 30,000 stock are killed every year because of it.
But while cattle farmers may support a cull, a government consultation of more than 47,000 people suggested that more than 95% of people opposed it.
One angry farmer shouted that the government had done nothing to tackle bovine TB in 10 years, adding: "Stop waffling."
Answering his heckler, Mr Benn said: "I'm not waffling. I'm going to take a decision and we're going to have to find a way forward."
He said a 10-year study by the Independent Scientific Group on bovine TB concluded that a badger cull could not "meaningfully contribute" to control of the disease in cattle.
And he said he was awaiting a report by the Environment Food and Rural Affairs select committee, due within weeks, before making a decision.
Mr Kendall said it was "disappointing" Mr Benn referred only to the ISG report rather than one by former chief scientist Sir David King, which drew different conclusions.
Earlier, in his speech to the conference Conservative leader David Cameron criticised the government's record on delivering the Single Farm Payments subsidies, containing foot-and-mouth disease, on "red tape" and its "arrogance" towards country life.
He also said the UK's self sufficiency in food production dropped from 72% in 1996 to 60% today and warned of a potential "food crunch" in future.
More meat consumption in India and China, more bio fuels and climate change are putting pressure on global grain supplies, the Tory leader said.
"We face the potential prospect that the abundance of food that we all take for granted will come to a crashing end," he said.
"Yet just as we are relying - indeed we are depending more and more - on foreign farmers to fill our shopping bags, cupboards and fridges, so the days of abundant food from around the world may well be coming to an end."
He said British food production should be boosted to secure the nation's food supply and outlined measures which could be taken to protect British farmers.
These included stopping production subsidies across the whole of Europe and reducing bureaucracy to create a "level playing field".