Big publishing companies are partly to blame for producing virtually identical set books, Chris Kington told the association's annual conference at the University of Derby.
The problem, he said, is compounded by the growing number of non-specialist teachers taking geography lessons in secondary schools.
Mr Kington said: "The problem for teachers who do not have a secure hold of the subject is that they minimise the risk by sticking to the script of a textbook.
"This belt and braces, lowest common denominator approach is good for book sales but bad for education."
Mr Kington, who runs two small educational publishers, said teachers were hampered by a lack of resources to buy books. State schools spend pound;1 per pupil per year on books and resources, compared with a figure of pound;3.56 for private schools.
The situation was exacerbated by the centralised curriculum, in which the Government dictated what was taught in schools.
Seven major publishing companies dominated the market, Mr Kington said, offering very little choice.
His comments come after reports of a possible link between multi-national publisher Pearson and the exam board Edexcel, which Mr Kington said stood to make the situation worse.
Afterwards, Mr Kington told The TES that when pupils were asked to provide case studies to support their answers in GCSE exams, they often came up with identical responses taken from the same textbook.
The Qualifications and Curriculum Agency is attempting to give geography a wider appeal by piloting a GCSE offering vocational elements, including town planning and tourism.
It is also starting a new drive to promote creativity in the classroom. A website is to be set up giving teachers the chance to share lesson ideas and link with university geography lecturers following a two-year review of the curriculum.