Defra missed 34% of its own business plan deadlines over the last year, according to research by a thinktank.
A report by the Institute for Government ranked 17 Whitehall departments based on how they had kept to timetables for planned actions.
Defra was found to be one of the worst offenders, second only to the Department of Health which missed 53% of its deadlines.
Institute for Government senior researcher Justine Stephen said: “The principle of getting departments to set out what they are going to do, when they will do it and whether this has happened is a good one and is to be applauded. At the moment, we can say who has missed the most deadlines or completed the most actions.
“However, the business plans are not yet delivering real democratic accountability, as it is still difficult to access, understand or compare the information they contain.
“Until these issues are addressed, the prime minister’s goal of a new system of accountability to the people will remain a work-in-progress.”
A Defra spokesman said: “We are committed delivering our business plan with more than half of the actions set out already completed. The vast majority of delayed actions were completed within three months of the target date.
“Delays have occurred to ensure that the department gave full consideration to the responses from public consultations.”